taxonID	type	description	language	source
846787B2FFF7F263FF76FA99FE2A08CA.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 253 colonies (123 with sporosarcs), of which 77 growing on Idiellana pristis, 27 on Diphasia digitalis, 15 on unidentified hydroids, three on Tridentata loculosa, two on Tridentata turbinata, two on Eudendrium capillare, one on Halecium marocanum, one on Plumularia setacea, one on Amphisbetia distans, one on Thyroscyphus marginatus, 75 on unidentified bryozoans, one on a polychaete tube. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: 68 colonies (two with sporosacs), 30 – 47 mm high, of which 19 growing on Idiellana pristis, three on Diphasia digitalis, two on Thyroscyphus marginatus, two on Tridentata loculosa, one on Tridentata marginata, 20 on bryozoans, two on crustaceans, one on a polychaete tube. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: five colonies (four with sporosacs), up to 31 mm high, of which four growing on bryozoans. CCLME 2012 - 404, stn SL− 04, 10 º 48 ’ 29 ’’ N, 16 º 34 ’ 57 ’’ W, 32 m, 18 - VI- 2012: one colony growing on Eudendrium sp., without sporosacs.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF7F263FF76FA99FE2A08CA.taxon	discussion	Remarks. Our material is consistent with that described by Gil et al. (2020), and requires no further notes. It represents also the first record of B. vestita for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF7F263FF76FA99FE2A08CA.taxon	biology_ecology	Biology. This species has been found growing on other hydroids and invertebrates (Gil et al. 2020). Specimens with gonophores were found in early summer, and from August to February in the northern hemisphere, while in the southern hemisphere they occurred from spring to autumn (Gil et al. 2020). Colonies studied by us were found growing on hydroids, bryozoans, worm tubes and crustaceans. Colonies with sporosacs were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF7F263FF76FA99FE2A08CA.taxon	distribution	Distribution. Bimeria vestita is considered as a species with a circumglobal distribution (Vervoort 2006). In West Africa, it occurrence was thoroughly documented by Gil et al. (2020). Its bathymetric distribution ranges from 0 (Schuchert 2012) to 574 m (Gil et al. 2020). Our material was collected between 20 – 32 m. Genus Garveia Wright, 1859	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F263FF76FD11FCE50F21.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 45 colonies (all without gonophores), of which 19 growing on Idiellana pristis, four on Diphasia digitalis, two on Tridentata loculosa, one on an unidentified hydroid, and four on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F263FF76FD11FCE50F21.taxon	discussion	Remarks. Our material agrees well with those described by Ramil & Vervoort (1992 a) from the Strait of Gibraltar and by Gil et al. (2020) from coral mounds of Mauritania, and no further discussion is necessary. Our finding represents also the first record of G. nutans for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F263FF76FD11FCE50F21.taxon	biology_ecology	Biology. This species has been found growing on various hard substrates, stones, algae, other hydroids, Madrepora oculata Linnaeus, 1758, and on Acesta excavata (J. C. Fabricius, 1779) (Schuchert 2007; Gil et al. 2020). Colonies with gonophores have been found between February and December in the northern hemisphere (Schuchert 2012; Gil & Ramil 2017 a; Gil et al. 2020). Our colonies were found growing on other hydroid species and bryozoans. No fertile material was observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F263FF76FD11FCE50F21.taxon	distribution	Distribution. Garveia nutans has a circumglobal distribution in boreal and temperate regions (Ramil & Vervoort 1992 a; Bouillon et al. 2006) and, in West Africa, it was only recorded from Mauritania (Gil & Ramil 2017 a; Gil et al. 2020). Its bathymetric distribution ranges between 0 (Schuchert 2007, 2012) and 1339 m (Gil & Ramil 2017 a). Our material was collected at depths between 24 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F260FF76F9EDFCE50B9F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: three colonies growing on bryozoans, of which one bearing medusa buds.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F260FF76F9EDFCE50B9F.taxon	discussion	Remarks. The material collected in Northwest Africa is similar to those recorded from Galicia by Ramil (1988), Ansín Agís (1992) and Ramil et al. (1998), and represents the first record of L. octona for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F260FF76F9EDFCE50B9F.taxon	biology_ecology	Biology. Leuckartiara octona lives mostly epizootically on crustaceans, mollusks, worm tubes, stones, fragmented shells, poriferans, hydroids and, notably, on the parapodia of the sea mouse Aphrodita (Rees & Thursfield 1965; Ansín Agís 1992; Ramil & Vervoort 1992 a; Schuchert 2012). Polyps with medusa buds were found from April to October in the northern hemisphere (Christiansen 1972; Schuchert 2007). In our material, all colonies were attached to bryozoans. Medusa buds were recorded for the first time in this species in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF6F260FF76F9EDFCE50B9F.taxon	distribution	Distribution. This is a circumglobal species in subtropical and temperate waters (Gil & Ramil 2021 b). In West Africa, it has been recorded from Morocco (Ramil & Vervoort 1992 a), Mauritania (Gil & Ramil 2017 a) and Vema Seamount (Gil & Ramil 2021 b). Its bathymetric distribution ranges between the intertidal (Millard 1975) and 541 m (Gil & Ramil 2021 b). Our material was collected at depths between 24 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F260FF76FD10FCE50F05.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: two colonies without gonophores, of which one growing on an unidentified hydroid. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: one colony without gonophores, growing on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F260FF76FD10FCE50F05.taxon	discussion	Remarks. The presence of two sizes of macrobasic euryteles, particularly the larger one, is a distinctive feature of E. album (Schuchert 2012). Our colonies represent the first record of E. album for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F260FF76FD10FCE50F05.taxon	biology_ecology	Biology. This species has been found growing on stones, algae and other hydroids (Schuchert 2012). In the northern hemisphere, fertile material has been found between January and August (Schuchert 2012). In our material, some colonies were found growing on unidentified hydroids and a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F260FF76FD10FCE50F05.taxon	distribution	Distribution. Schuchert (2008) pointed out that most identifications of E. album do not include information on the cnidome, and should therefore be considered only as tentative. Eudendrium album is a boreo-Atlantic species, known to occur from Norway to Galicia, in the Mediterranean Sea (Schuchert 2008, 2012) and in Mauritania (Gil & Ramil 2017 a). Its bathymetric range extends from 0 to 1000 m (Schuchert 2008). Our material was collected at depths between 20 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F261FF76FA37FCE50873.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 1363 colonies (871 with gonophores), 6 – 49 mm high, of which 368 growing on Idiellana pristis, 314 on bryozoans, 108 on Diphasia digitalis, 40 on Tridentata loculosa, 16 on worm tubes, 10 on unidentified hydroids, nine on crustaceans, eight on Tridentata marginata, five on Dynamena disticha, five on Tridentata turbinata, four on Eudendrium ramosum, four on bivalves, one on Bimeria vestita, one on Halecium lankesteri, one on Halecium sp. and one on Clytia gracilis. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: six colonies without gonophores, of which one growing on Eudendrium sp.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F261FF76FA37FCE50873.taxon	discussion	Remarks. The nematocysts in our material, microbasic euryteles and isorhizas, correspond to those described for this species by Schuchert (2008, 2012). Records of this species from Ghana (Vervoort 1959, as Eudendrium cf. capillare) are considered as doubtful, because the material was identified on general morphological grounds solely; moreover, all colonies were sterile. Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F261FF76FA37FCE50873.taxon	biology_ecology	Biology. This species grows on a variety of substrates such as algae, and on invertebrates, such as sponges, hydroids, cirripeds, mollusk shells, bryozoans and ascidians (Peña Cantero & García Carrascosa 2002; Schuchert 2012). In the northern hemisphere, fertile material was found from April to November (Schuchert 2008, 2012). In our material, some colonies had gonophores in November. Most of the colonies were found growing on hydroids, bryozoans, bivalves, crustaceans and polychaete tubes.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF5F261FF76FA37FCE50873.taxon	distribution	Distribution. Eudendrium capillare is considered as nearly cosmopolitan, but many records are doubtful because they are not based on the study of the nematocysts (Schuchert 2012). Therefore, when the records based on the cnidome are taken into account, E. capillare shows a circumglobal distribution (Schuchert 2008). In West Africa, it has been recorded from Morocco (Ramil & Vervoort 1992 a; Vervoort 2006), Mauritania (Billard 1906 a) and Ghana (Vervoort 1959). Its bathymetric distribution ranges from 0 to 80 m (Schuchert 2012). Our material was collected at depths between 21 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF4F261FF76FD2CFC000CBE.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 30 colonies, 28 – 113 mm high, without gonophores, of which two growing on Diphasia digitalis, and one on a polychaete tube. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: four colonies, 47 – 70 mm high, all without gonophores, substrate unknown. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: five colonies, 24 – 88 mm high, all without gonophores, substrate unknown. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: one colony without gonophores, attached to a bryozoan. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: one colony without gonophores, epizoic on Nemertesia ramosa.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF4F261FF76FD2CFC000CBE.taxon	discussion	Remarks. The study of nematocysts allowed us to identify this material as E. ramosum.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF4F261FF76FD2CFC000CBE.taxon	biology_ecology	Biology. This species has been found growing on hard substrates, whether artificial or organic, such as algae and other invertebrates, e. g. bryozoans, gastropods, bivalves, anthozoans, polychaete tubes and other hydroids (Peña Cantero & García Carrascosa 2002; Gil & Ramil 2021 b). In the northern hemisphere, colonies with gonophores have been found between March and December (Peña Cantero & García Carrascosa 2002; Schuchert 2012; Gil & Ramil 2017 a), while in the southern hemisphere, fertile material was found in February (Gil & Ramil 2021 b). In our material, E. ramosum was found growing on D. digitalis, N. ramosa, a polychaete tube and a bryozoan. Gonophores were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFF4F261FF76FD2CFC000CBE.taxon	distribution	Distribution. Eudendrium ramosum is considered as a cosmopolitan species; nevertheless, many of its records are doubtful (Ramil & Vervoort 1992 a; Marques et al. 2000), especially those from outside the eastern Atlantic (Schuchert 2012). In West Africa, it was recorded from Morocco (Ramil & Vervoort 1992 a; Vervoort 2006) to the Cape Verde (Ritchie 1907; Vervoort 2006), and from the Valdivia Seamount (Gil & Ramil 2021 b). Its bathymetrical range starts from the tidal zone (Ansín Agís 1992), reaching depths as much as 1870 m (Ramil & Vervoort 1992 a). The material studied by us was collected at depths between 21 – 58 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27EFF76FF35FDE50FCC.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 142, 11 º 14 ' 17 " – 11 º 13 ' 22 " N, 17 º 13 ' 07 " – 17 º 13 ' 12 " W, 335 – 393 m, 25 - X- 2008: one colony, without gonothecae. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 116 colonies, 2 – 35 mm high, all without gonothecae, of which 36 growing on Diphasia margareta, 32 on Lytocarpia myriophyllum, seven on Sertularella gayi, six on Lafoea gracillima, five on Earleria panicula, three on Aglaophenia lophocarpa, three on Aglaophenia tubulifera, one on Eudendrium sp., one on Nemertesia ventriculiformis, one on Diphasia sp., and four on worm tubes. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: one colony without gonothecae, growing on Sertularella gayi. BISSAU- 0810, stn BS 177, 10 º 10 ' 16 " – 10 º 11 ' 00 " N, 17 º 07 ' 21 " – 17 º 07 ' 54 " W, 382 – 387 m, 31 - X- 2008: one colony without gonothecae growing on Lytocarpia myriophyllum.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27EFF76FF35FDE50FCC.taxon	discussion	Remarks. Modeeria rotunda is a well-known species and does not require a further discussion.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27EFF76FF35FDE50FCC.taxon	biology_ecology	Biology. This species is usually found on other hydroids, but also on ascidians, anthozoans and bio-concretions (Peña Cantero & García Carrascosa 2002). In the northern hemisphere, fertile material has been found from April to June, and in September, November and December (Peña Cantero & García Carrascosa 2002; Vervoort 2006; Gil & Ramil 2017 a). In our material, most of the colonies were growing on different species of hydroids, as well as on worm tubes. No fertile material was collected.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27EFF76FF35FDE50FCC.taxon	distribution	Distribution. Modeeria rotunda is a cosmopolitan species (Ramil & Vervoort 1992 a; Vervoort 2006). In West Africa, it has been collected from Morocco (Patriti 1970; Ramil & Vervoort 1992 a), Mauritania (Vervoort 2006; Gil & Ramil 2017 a), the Cape Verde (Stechow 1925; Vervoort 2006), Senegal, Guinea-Bissau, Liberia, Ghana, Nigeria, Namibia (Buchanan 1957; Vervoort 1959, as Stegopoma fastigiatum; Gili et al. 1989) and the Vema Seamount (Gil & Ramil 2021 b). Its bathymetric distribution extends from 0.5 (García Carrascosa 1981) to 1554 m (Gil & Ramil 2017 a). Our material was collected at depths between 300 – 393 m. Genus Stegopoma Levinsen, 1893	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27FFF76FA12FB160B53.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: one colony, 105 mm high, with gonothecae. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: five colonies, 21 – 105 mm high, without gonothecae, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27FFF76FA12FB160B53.taxon	discussion	Remarks. Our material is indistinguishable from that described earlier by Ramil & Vervoort (1992 a). We recorded fertile colonies for the first time in October, and our finding represents also the first record of S. bathyale for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27FFF76FA12FB160B53.taxon	biology_ecology	Biology. In the northern hemisphere, colonies with gonothecae have been found in June (Ramil & Vervoort 1992 a). In our material, one colony with gonothecae was found in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEBF27FFF76FA12FB160B53.taxon	distribution	Distribution. Stegopoma bathyale has been found in the Gulf of Bengal (type locality) and several deep-water Atlantic localities (Gil & Ramil 2017 a). In West Africa, it is known from Morocco (Ramil & Vervoort 1992 a) and Mauritania (Vervoort 2006; Gil & Ramil 2017 a). Its bathymetric distribution extends from 394 to 1592 m (Ramil & Vervoort 1992 a). Colonies studied herein were collected from Guinea-Bissau, at depths between 300 – 308 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27FFF76FE5CFCE50FE2.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 138 colonies, all without gonothecae, of which nine growing on unidentified hydroids, eight on Idiellana pristis, four on Diphasia digitalis, two on Amphisbetia distans, 41 on Eudendrium capillare, two on Obelia dichotoma, one on Sertularella polyzonias, one on Tridentata turbinata, two on Halecium marocanum, three on Garveia nutans, one on Tridentata loculosa, two on Bimeria vestita, two on Filellum cf. serratum, three on crustaceans, one on a polychaete tube, and 42 on bryozoans. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: one colony without gonothecae growing on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27FFF76FE5CFCE50FE2.taxon	discussion	Remarks. The colonies studied herein agree with those described by Gil et al. (2020), and represent the first record of this species for Guinea-Bissau. No further discussion is required.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27FFF76FE5CFCE50FE2.taxon	biology_ecology	Biology. This species has been reported growing on a great variety of substrates, such as rocks, algae, hydroids, bryozoans, anthozoans and cirripedes (Peña Cantero & García Carrascosa 2002; Migotto & Cabral 2005, both as E. amiratensis; Gil et al. 2020). In the southern hemisphere, colonies with gonothecae have been found in summer (Millard & Bouillon 1973; Migotto & Cabral 2005). The colonies studied herein were found growing on hydroids, crustaceans, worm tubes and bryozoans. Fertile material was not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27FFF76FE5CFCE50FE2.taxon	distribution	Distribution. Cirrholovenia tetranema is considered as a circumglobal species (Migotto & Cabral 2005). In West Africa, it was collected from Morocco (Ramil & Vervoort 1992 a) and Mauritania (Gil & Ramil 2017 a). Its bathymetrical distribution ranges from 1 (Calder 1991, as Lafoeina amiratensis) to 1161 m (Ríos et al. 2022). Our material was collected at depths between 21 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27CFF76F92FFF2908E7.taxon	materials_examined	Material examined. CCLME 2012 - 404, stn SL- 04, 10 º 48 ’ 29 ’’ N, 16 º 34 ’ 57 ’’ W, 32 m, 18 - V- 2012: one colony with a gonotheca growing on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27CFF76F92FFF2908E7.taxon	discussion	Remarks. In the colony studied herein, the distal half of the hydrothecal wall was undulated and the gonotheca was completely ringed, whereas the gonothecae described by Cornelius (1995 a) had only slightly undulated walls. Our finding represents the first record of L. clausa for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27CFF76F92FFF2908E7.taxon	biology_ecology	Biology. Usually, L. clausa has been found growing on gastropod and bivalve shells (Ramil 1988; Ramil et al. 1998; Peña Cantero & García Carrascosa 2002), Turritella shells inhabited by the sipunculid Phascolion strombus (Montagu, 1804) (Teissier 1965; Ramil 1988), algae (Cornelius 1995 a), Amathia sp. (Peña Cantero & García Carrascosa 2002), and the scaphopod Antalis novemcostata (Lamarck, 1818) (Ramil et al. 1988). In the northern hemisphere, gonothecae have been found in January, March, April and June – September, but most frequently in the boreal autumn (Ramil 1988; Álvarez Claudio 1993; Cornelius 1995 a). Our material was found growing on a bryozoan. A gonotheca was observed in May.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEAF27CFF76F92FFF2908E7.taxon	distribution	Distribution. This species has an East-Atlantic distribution, from Sweden (Hincks 1869) to the Cape Verde Islands (Vervoort 2006). In the Mediterranean, the species has been reported from the Alboran Sea, but additional records are doubtful (Peña Cantero & García Carrascosa 2002). In West Africa, it has been collected from Morocco (Patriti 1970) and the Cape Verde Islands (Vervoort 2006). Its bathymetric distribution ranges from 0 (Cornelius 1995 a) to 161 m depth (Álvarez Claudio 1993). Our material was collected at a depth of 32 m, and represents the southernmost record of this species for the Atlantic.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27CFF76FD58FCE50C09.taxon	description	(Fig. 3 A)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27CFF76FD58FCE50C09.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 20 colonies (five with gonothecae), up to 9 mm high, of which two growing on bryozoans, one on Idiellana pristis, one on Diphasia digitalis, and one a crustacean. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: one colony, 14 mm high, without gonothecae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27CFF76FD58FCE50C09.taxon	discussion	Remarks. We found gonothecae for the first time in November. Our material represents the first record of L. corrugata for Guinea-Bissau, and agrees well with the colonies described by Vervoort (1959) from the Republic of Guinea. We identified this material as L. corrugata based on the geniculate habit of the colony, the presence of annuli close to each internode, and the distinctive shape of the gonothecae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27CFF76FD58FCE50C09.taxon	biology_ecology	Biology. In the northern hemisphere, colonies with gonothecae have been found in February (Vervoort 1959). Thornely (1908) described the gonothecae, but the collection dates of her material were not provided. In our samples, some colonies were growing on the hydroids I. pristis and D. digitalis, as well as on various bryozoans and crustaceans. Fertile material was found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27CFF76FD58FCE50C09.taxon	distribution	Distribution. There are a few records of this species worldwide. Lovenella corrugata has been recorded from the Sudanese Red Sea (Thornely, 1908, type locality) and West Africa, from Guinea Conakry (Vervoort 1959), the Ivory Coast (Redier 1971) and Togo (Broch 1914). Its bathymetric distribution ranges from 8 – 55 m (Vervoort 1959). Our material was collected at depths between 24 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27DFF76F885FC810883.taxon	description	(Fig. 3 B)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27DFF76F885FC810883.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: five colonies without gonothecae, up to 10 mm high, of which two growing on Lytocarpia myriophyllum and another one on a worm tube. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: two colonies, up to 14 mm high, of which one with gonothecae and growing on Lytocarpia myriophyllum.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27DFF76F885FC810883.taxon	discussion	Remarks. The morphology of our colonies and the shape of the gonotheca match those described earlier by Gili et al. (1989). This is the second record of P. anitae from West Africa.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27DFF76F885FC810883.taxon	biology_ecology	Biology. This species has been found growing on coral rubble (Calder & Vervoort 1986), dead mollusk shells (Vervoort 2006), worm tubes and the hydroid Sertularella gayi (Gili et al. 1989). In the northern hemisphere, colonies with gonothecae have been found in February (Calder 2013). In our material, some colonies were found on L. myriophyllum and a worm tube. Gonothecae were found in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE9F27DFF76F885FC810883.taxon	distribution	Distribution. This is a circumglobal species (Vervoort 2006). In West Africa, it has been already recorded from Guinea-Bissau (Gili et al. 1989). Its bathymetric distribution ranges from 60 (Calder & Vervoort 1986) to 1480 m depth (Vervoort & Watson 2003). Our material was collected at depths between 300 – 308 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE8F27BFF76FC0CFDE10AFF.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 142, 11 º 14 ' 17 " – 11 º 13 ' 22 " N, 17 º 13 ' 07 " – 17 º 13 ' 12 " W, 335 – 393 m, 25 - X- 2008: two colonies, without gonothecae. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 79 colonies, 3 – 30 mm high, without gonothecae, of which seven growing on Diphasia margareta, 51 on Lytocarpia myriophyllum, four on Nemertesia irregularis, one on Turritopsis sp., four on Aglaophenia tubulifera, one on Nemertesia ventriculiformis, two on a rope, one on a polychaete tube. BISSAU- 0810, stn BS 177, 10 º 10 ' 16 " – 10 º 11 ' 00 " N, 17 º 07 ' 21 " – 17 º 07 ' 54 " W, 382 – 387 m, 31 - X- 2008: one colony growing on Lytocarpia myriophyllum, without gonothecae. BISSAU- 0810, stn BS 182, 10 º 14 ' 14 " – 10 º 13 ' 22 " N, 16 º 32 ' 49 " – 16 º 32 ' 44 " W, 211 – 224 m, 1 - XI- 2008: one colony growing on L. myriophyllum, without gonothecae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE8F27BFF76FC0CFDE10AFF.taxon	discussion	Remarks. Our material agrees with that described by Gil et al. (2020) from Mauritanian coral mounds, and it represents the first record of this species for Guinea-Bissau. No further discussion is necessary.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE8F27BFF76FC0CFDE10AFF.taxon	biology_ecology	Biology. This species has been found growing on a great variety of invertebrates (Cornelius 1995 a, as Campanulina panicula; Calder 2012, as Racemoramus panicula). In the northern hemisphere, fertile material has been found in April, June, November and December (Ramil & Vervoort 1992 a, as Opercularella panicula; Cornelius 1995 a, as C. panicula; Gil & Ramil 2017 a, as R. panicula), while in the southern hemisphere, gonothecae were found in August (Gili et al. 1989, as O. denticulata). In our material, colonies were found growing on other hydroid species, a worm tube and artificial substrates, such as a rope. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE8F27BFF76FC0CFDE10AFF.taxon	distribution	Distribution. Earleria panicula is considered as an Eastern Atlantic species (Calder 2012, as R. panicula; Gil et al. 2020), with a bathymetric distribution ranging from 30 to 2100 m (Christiansen 1972, as O. panicula; Ramil & Vervoort 1992 a, as R. panicula). In West Africa, it has been recorded from Morocco, Mauritania and Namibia (Gili et al. 1989, as O. denticulata; Gil et al. 2020). Our material was collected at depths between 460 – 462 m. Genus Cyclocanna Bigelow, 1918	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF27BFF76FF7DFE4E0824.taxon	materials_examined	Material examined. CCLME 2011 - 410, stn GR- 04, 10 º 26 ′ 47 ′′ N, 17 º 22 ′ 43 ′′ W, 504 m, 28 - X- 2011: one colony growing on a worm tube, without gonothecae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF27BFF76FF7DFE4E0824.taxon	discussion	Remarks. This material was previously dealt with in Gil & Ramil’s (2023 a) study of the genus Egmundella from Northwest Africa.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF278FF76FCEEFDD00AFF.taxon	description	(Fig. 3 C)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF278FF76FCEEFDD00AFF.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 131, 11 º 34 ' 07 " – 11 º 33 ' 13 " N, 17 º 11 ' 25 " – 17 º 11 ' 31 " W, 102 – 103 m, 23 - X- 2008: one colony, 60 mm high, without gonothecae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF278FF76FCEEFDD00AFF.taxon	discussion	Remarks. The material studied herein agrees with those described by Ramil & Vervoort (1992 a) as Acryptolaria conferta conferta (Allman, 1877). We followed Peña Cantero et al. (2007), and studied the cnidome of our specimens that revealed two size classes of the same type of nematocysts, larger capsules (14 – 17 μm long, 5 – 6 μm wide) and smaller capsules (7 – 8 μm long, 3 – 4 μm wide). Upon a comparison with Acryptolaria conferta var. minor Ramil & Vervoort, 1992, collected during the SEAMOUNT- 1 expedition, it was realized that the nematocysts of the latter were of the same type as those of A. conferta conferta, but differing in size, viz. (18 – 19 μm long, 6 – 7 μm wide) and (9 – 11 μm long, 4 – 8 μm wide), respectively. This difference between the nematocysts of the two morphotypes, together with the size range observed by Ramil & Vervoort (1992 a) and the absence of intermediate forms (Gil et al. 2020) seems to reinforce the separation of these so-called two varieties. This is the first time that the nematocysts of both forms have been studied, and it appears that the cnidome is a reliable character to be used whenever possible. Our finding represents the first record of A. conferta var. conferta for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF278FF76FCEEFDD00AFF.taxon	biology_ecology	Biology. This species has been reported growing on different substrates, such as bryozoans, sponges, coral fragments and stones (Ramil & Vervoort 1992 a; Vervoort 2006). In the northern hemisphere, coppiniae have been found from May to July (Ramil & Vervoort 1992 a; Calder 1991; Vervoort 2006).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEEF278FF76FCEEFDD00AFF.taxon	distribution	Distribution. Acryptolaria conferta conferta is a circumglobal species occurring in moderately deep to deep waters (Vervoort 2006). In West Africa, it has been collected from Morocco (Patriti 1970; Ramil & Vervoort 1992 a) and Mauritania (Vervoort 2006; Gil & Ramil 2017 a). Its bathymetric distribution ranges from 52 to 2050 m (Vervoort 2006). Our material was collected at depths between 102 – 103 m. Genus Filellum Hincks, 1869	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF278FF76FF7DFDF80C2E.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: one colony without coppiniae, growing on Nemertesia ramosa. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: three colonies without coppiniae, of which one growing on Lytocarpia myriophyllum and the two others on Aglaophenia lophocarpa. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 183 colonies without coppiniae, of which 125 growing on bryozoans, 13 on unidentified hydroids, 12 on Eudendrium capillare, 10 on Idiellana pristis, four on Diphasia digitalis, two on Bimeria vestita, two on Amphisbetia distans, one on Garveia nutans, one on Sertularella sp., one on Tridentata marginata, one on Tridentata loculosa, one on Obelia dichotoma, and one on a crustacean. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: seven colonies without coppiniae, of which six growing on an unidentified hydroid. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: two colonies without coppiniae, growing on Sertularelloides cylindritheca. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: one colony without coppiniae, growing on Halecium halecinum.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF278FF76FF7DFDF80C2E.taxon	discussion	Remarks. The present material is consistent with that described by Gil et al. (2020), also as Filellum cf. serratum, and represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF278FF76FF7DFDF80C2E.taxon	biology_ecology	Biology. Filellum serratum has been found growing on a wide variety of invertebrates, mainly hydroids (Peña Cantero et al. 1998; Vervoort 2006; Gil et al. 2020). In the northern hemisphere, fertile material has been found in July and August (Peña Cantero et al. 1998), while in the southern hemisphere, coppinae were found in March (Ritchie 1911). In our material, colonies were found growing on hydroids, bryozoans and crustaceans. Coppinae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF278FF76FF7DFDF80C2E.taxon	distribution	Distribution. Filellum serratum is considered as a circumglobal species (Peña Cantero et al. 1998); nevertheless, some records based on sterile material are doubtful (Vervoort 2006; Gil et al. 2020). In West Africa, it has been recorded from the Canary Islands (Vervoort 2006), Mauritania (Gil & Ramil 2017 a; Gil et al. 2020) and the Cape Verde Archipelago (Vervoort 2006). Its bathymetric distribution ranges from 0 – 2000 m (Millard 1978; Calder 1998). Our material was collected at depths between 24 – 306 m. Genus Lafoea Lamouroux, 1821	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF279FF76F92FFC93095B.taxon	description	(Fig. 3 D)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF279FF76F92FFC93095B.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 132, 11 º 31 ' 33 " N, 17 º 14 ' 07 " W, depth unknown, 23 - X- 2008: three colonies without coppiniae, up to 3 mm high, of which one growing on a polychaete tube and another on Desmophyllum pertusum. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 51 colonies without coppiniae, 6 – 58 mm high, of which 14 growing on Diphasia margareta, nine on Lytocarpia myriophyllum, three on Aglaophenia lophocarpa, three on Aglaophenia tubulifera, one on Diphasia sp., two on polychaete tubes and two on bryozoans. BISSAU- 0810, stn BS 177, 10 º 10 ' 16 " – 10 º 11 ' 00 " N, 17 º 07 ' 21 " – 17 º 07 ' 54 " W, 382 – 387 m, 31 - X- 2008: one colony without coppiniae, 18 mm high. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony without coppiniae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF279FF76F92FFC93095B.taxon	discussion	Remarks. The taxonomic status of L. gracillima has recently been discussed by Calder (2012) and Gil et al. (2020). Our material is consistent with that described by Gil et al. (2020) from the coral mounds off Mauritania. This is the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF279FF76F92FFC93095B.taxon	biology_ecology	Biology. This species has been found growing on different types of bottoms (Jäderholm 1909), on Tubularia indivisa Linnaeus, 1758 (Calder 2012), on M. oculata and the bivalve A. excavata (Gil et al. 2020). In our material, colonies were found growing on hydroids, worm tubes, bryozoans and D. pertusum. Coppiniae where not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFEDF279FF76F92FFC93095B.taxon	distribution	Distribution. Lafoea gracillima is considered as an amphi-Atlantic species (Calder 2012; Gil et al. 2020). In West Africa, it has been recorded from Morocco to the Cape Verde Archipelago (Gil et al. 2020). Its bathymetric distribution ranges from 20 – 30 m (Calder 2012) to 640 m depth (Gil et al. 2020). Our material was collected at depths between 24 – 387 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFECF277FF76FC54FC91082F.taxon	description	(Fig. 4 A; Table 1)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFECF277FF76FC54FC91082F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 420 colonies (35 with gonothecae), of which 417 growing on unidentified hydroids, one on a worm tube, one on a bryozoan and one on a crustacean. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: 16 colonies (15 of them with gonothecae), all growing on unidentified hydroids. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: six colonies with gonothecae, all growing on unidentified hydroids.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFECF277FF76FC54FC91082F.taxon	description	Description. Colonies stolonal. Hydrothecae borne on short and slightly undulated pedicels, arising from a thin stolon, usually growing along the stems and hydrocladia of a syntheciid colony, and close to the hydrothecae of the host; long, almost cylindrical, tapering and rounded below, and there separated from the pedicel by a thin, transversely-set membrane; aperture distal, transverse, circular in apical view, with slightly everted margin, and usually with 2 – 3 renovations. Gonothecae much bigger than the hydrothecae, exceedingly long, with almost parallel walls, gradually narrowing towards base, attached to stolon by a short, curved stalk. Aperture circular, closed by a membrane with a hemispherical depression (Fig. 4 A).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFECF277FF76FC54FC91082F.taxon	discussion	Remarks. Our material is consistent with that described by Vervoort (1959) from the Republic of Guinea, and allows the description of the gonothecae of this species for the first time. Hebella ritchiei is a species considered as doubtful by Boero et al. (1997) and a taxon inquirendum in WoRMS. This is evidently due to the morphology of its trophosome that is similar to that of other Hebella species, such as H. scandens (Bale, 1888) or H. plana Ritchie, 1907. However, the morphology of its gonotheca is completely different from that of the other species, allowing us to support the specific validity of this hydroid. Currently, the status of the family Hebellidae is doubtful (Calder & Faucci 2021). During the last decades, several life cycle and genetic studies have been carried out by different authors (Migotto & Andrade 2000; Marques et al. 2006; Peña Cantero et al. 2010; Moura et al. 2012; Maronna et al. 2016), establishing that this family is polyphyletic and in need of a thorough revision.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFECF277FF76FC54FC91082F.taxon	biology_ecology	Biology. Hebella ritchiei was found growing on Hincksella cylindrica (Bale, 1888) (Vervoort 1959). Gonothecae were unknown. In our material, almost all colonies were growing on unidentified hydroids; in addition, three colonies were collected from a worm tube, a bryozoan and a crustacean, respectively. Colonies with gonothecae, previously unknown in this species, were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFECF277FF76FC54FC91082F.taxon	distribution	Distribution. This species was recorded from Australia by Ritchie (1911, as Lafoea tenellula) and the Republic of Guinea by Vervoort (1959). Its bathymetric distribution ranges from 30 (Vervoort 1959) to 108 m (Ritchie 1911). Our colonies were collected at depths between 21 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE2F274FF76FB28FCE5095B.taxon	description	(Fig. 4 B – D)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE2F274FF76FB28FCE5095B.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 143, 11 º 15 ' 35 " – 11 º 16 ' 30 " N, 17 º 09 ' 49 " – 17 º 09 ' 49 " W, 95 – 96 m, 25 - X- 2008: one colony growing on Sertularelloides cylindritheca, without gonothecae. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 35 colonies (7 with gonothecae), of which 22 growing on Idiellana pristis, four on unidentified hydroids, one on Eudendrium capillare, one on Bimeria vestita, one on Halecium marocanum, one on Tridentata loculosa and one on Tridentata marginata. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: three colonies (one colony with gonothecae), of which one growing on an unidentified hydroid, one on Diphasia digitalis and one on Idiellana pristis. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: two colonies without gonothecae, both growing on Sertularelloides cylindritheca. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: one colony without gonothecae, growing on an unidentified hydroid. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: 44 colonies without gonothecae, all growing on Sertularelloides cylindritheca.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE2F274FF76FB28FCE5095B.taxon	discussion	Remarks. Most of the colonies found in the Bissau- 0811 material occurred on several species of sertulariids, a situation also documented by Peña Cantero & García Carrascosa (2002).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE2F274FF76FB28FCE5095B.taxon	biology_ecology	Biology. As in our material, this species has been usually found as an epibiont of other hydroids, but it has also been found growing on algae, sponges and bryozoans (Peña Cantero & García Carrascosa 2002). In the northern hemisphere, fertile material has been found in July, August and December (Vervoort 1959; Altuna 1994 b; Peña Cantero & García Carrascosa 2002), while in the southern hemisphere, gonothecae were found in January, February, April, August to October (Millard 1957; Millard & Bouillon 1973; Migotto 1996). In our material, some colonies were colonizing different species of hydroids. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE2F274FF76FB28FCE5095B.taxon	distribution	Distribution. Hebella scandens is a circumglobal species (Peña Cantero & García Carrascosa 2002; Galea 2013). In West Africa, it has been recorded from Western Sahara (Leloup 1937; Vervoort 1946, both as Hebella calcarata), Mauritania (Billard 1931 b; Vervoort 1946, both as H. calcarata), Guinea-Bissau (Gili et al. 1989), the Republic of Guinea, the Ivory Coast (Vervoort 1959), Ghana (Buchanan 1957, as H. calcarata; Vervoort 1959). Gabon (Vervoort 1959) and Angola (Broch 1914; Bouillon et al. 1995, as H. michaelseni). Its bathymetric distribution ranges from 0 to 164 m (Millard 1975). Our material was collected at depths between 24 – 96 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE0F272FF76FCEEFD940AFF.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony without gonothecae growing on Bimeria vestita. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: two colonies, up to 12 mm high, without gonothecae; one of them growing on Idiellana pristis. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 24 colonies (3 with gonothecae), up to 15 mm high, of which 21 growing on bryozoans, and one epizootically on Idiellana pristis. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: five colonies (three with gonothecae), of which three growing on bryozoans. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: three colonies without gonothecae, of which two growing on Sertularelloides cylindritheca and one on Sertularella gayi.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE0F272FF76FCEEFD940AFF.taxon	discussion	Remarks. This is a well-known species that requires no further comments.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE0F272FF76FCEEFD940AFF.taxon	biology_ecology	Biology. This species has been found growing on a wide variety of substrates, including invertebrates (Peña Cantero & García Carrascosa 2002). In the northern hemisphere, fertile colonies have been found throughout the year (Peña Cantero & García Carrascosa 2002; Gil et al. 2020), while in the southern hemisphere, gonothecae were found in January (Gil & Ramil 2021 b), July and October (Millard 1966 a). In our material, colonies were found growing on hydroids and bryozoans. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE0F272FF76FCEEFD940AFF.taxon	distribution	Distribution. Campanularia hincksii is a circumglobal species (Peña Cantero & García Carrascosa 2002) widely distributed in West Africa (Gil et al. 2020) and also recorded from the Vema and Valdivia Seamounts (Gil & Ramil 2021 b). Its bathymetric distribution extends from the tidal level to a depth of 1200 m (Leloup 1940; Peña Cantero & García Carrascosa 2002). Our material was collected at depths between 20 – 79 m. Genus Orthopyxis L. Agassiz, 1862	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE7F272FF76FF7DFBFB0D5A.taxon	description	(Fig. 5 A – B; Table 3)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE7F272FF76FF7DFBFB0D5A.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 63 colonies (one with male gonothecae), up to 11 mm high, of which 23 growing on bryozoans, 11 on Idiellana pristis, six on Diphasia digitalis, two on Eudendrium capillare, two on crustaceans, one on Bimeria vestita and one on Tridentata loculosa. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: 13 colonies (two with male gonothecae), 19 – 39 mm high, of which six growing on bryozoans, one on Eudendrium sp., one on Halecium sp. and one on Idiellana pristis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE7F272FF76FF7DFBFB0D5A.taxon	description	Description. Colonies arising from filiform hydrorhiza adhering to substrate, composed of scattered pedicels, each bearing apically a hydrotheca. Pedicels usually long, irregularly undulated and never ramified. Undulations more pronounced in some parts than in others with, sometimes, transverse nodes, indicating breakage followed by regeneration. A sub-hydrothecal spherule between the hydrotheca and its corresponding pedicel. Hydrothecae deeply campanulate, smooth-walled, tapering towards base. Basal part rounded, with diaphragm formed by an annular thickening delimiting a small basal chamber. Hydrothecal rim circular, with 10 to 12 low rounded cusps separated by U-shaped incisions of equal dimension. Male gonothecae given off from stolon, long, elliptic, borne on short, undulated pedicels. Aperture circular, located at distal end. Female gonothecae not seen.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE7F272FF76FF7DFBFB0D5A.taxon	discussion	Remarks. The synonymy of this species given by Vervoort & Watson (2003) proved partly erroneous, with several South-American records reassigned to either Campanularia lennoxensis Jäderholm, 1903 (see Galea et al. 2009: 16 – 17) or Campanularia hartlaubi (El Beshbeeshy, 2011) (see Galea & Schories 2012 a: 59). Consequently, it is assumed that the records of O. mollis by Ralph (1957) and Vervoort & Watson (2003) likely belong to different species, based on their geographically remote areas of occurrence. Our material agrees well with those described by Stechow (1919) and Picard (1951 b) in terms of colony structure and measurements. However, O. mollis has only been recorded from the Mediterranean Sea and seems to be a species restricted to shallow waters. The present authors have studied abundant material collected from West Africa and have never recorded this species, possibly because their materials originated from deep waters. Ansín Agís et al. (2001) and Gil & Ramil (2017 a) have highlighted the importance of the Atlantic-Mediterranean species in West Africa, emphasising the importance of the current systems in the southward dispersion of sessile epifauna (Van Soes 1993). It is therefore not surprising that this first record of O. mollis for Guinea Bissau, stands also for the West Africa, as well.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE7F272FF76FF7DFBFB0D5A.taxon	biology_ecology	Biology. This species has been found growing on algae (Stechow 1919, as Clytia mollis; Picard 1951 b). In the northern hemisphere gonothecae have been found in August (Stechow 1919; Picard 1951 b). In our material, most of the colonies were growing on bryozoans and the hydroids I. pristis, T. loculosa, D. digitalis, E. capillare, B. vestita, Eudendrium sp. and Halecium sp.; however, two colonies were also found growing on crustaceans. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE7F272FF76FF7DFBFB0D5A.taxon	distribution	Distribution. This species has only been collected from the Mediterranean, and its distribution seems to be restricted to shallow waters (Picard 1951 b). Our colonies were collected from Guinea-Bissau at depths between 21 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE5F271FF76FD71FC9308E7.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: nine colonies without gonothecae, of which six growing on Lytocarpia myriophyllum, one on Turritopsis sp., one on Lafoea gracillima and one on Aglaophenia lophocarpa. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 219 colonies (90 with gonothecae), 16 – 19 mm high, of which 34 growing on Idiellana pristis, 33 on bryozoans, 31 on Eudendrium capillare, 26 on crustaceans, 14 on Diphasia digitalis, 10 on unidentified hydroids, four on Bimeria vestita, two on Tridentata loculosa, two on bivalves, one on Eudendrium ramosum, one on Halecium marocanum, one on Tridentata marginata, one on a worm tube, and one on a rope. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: three colonies without gonothecae, up to 22 mm high, of which one growing on Idiellana pristis and another one on a crustacean. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 14 colonies (seven with gonothecae), growing on bryozoans. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: 10 colonies (five with gonothecae), up to 5 mm high, of which seven growing on bryozoans, two on Idiellana pristis and one on Eudendrium ramosum. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: 21 colonies (12 with gonothecae), of which seven growing on bryozoans, three on Idiellana pristis, one on Diphasia digitalis, one on Tridentata marginata and one on a crustacean. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: eight colonies without gonothecae, of which seven growing on Halecium beanii. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: one colony without gonothecae, growing on Sertularelloides cylindritheca. CCLME- 1205, stn BT 318, 10 º 41 ' 43 " – 10 º 43 ' 12 " N, 16 º 48 ' 37 " – 16 º 48 ' 55 " W, 107 m, 18 - V- 2012: one colony 109 mm high without gonothecae, growing on a bivalve.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE5F271FF76FD71FC9308E7.taxon	discussion	Remarks. Our material conforms to that described by Ramil & Vervoort (1992 a). Deep, campanulate hydrothecae with acute, inwardly curved marginal cups inclined to one side, and urn-shaped, distally-truncate gonothecae, are diagnostic features of this species.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE5F271FF76FD71FC9308E7.taxon	biology_ecology	Biology. Clytia gracilis is a common epibiont of other hydroids, being also found on rocks and pebbles, algae, sponges, bryozoans, mollusk shells, mollusk eggs, worm tubes and barnacles (Peña Cantero & García Carrascosa 2002). In the northern hemisphere, gonothecae have been found from April to December (Peña Cantero & García Carrascosa 2002; Gil & Ramil 2017 a). In our material, it was found growing on hydroids, crustaceans, bryozoans, worm tubes and bivalves. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE5F271FF76FD71FC9308E7.taxon	distribution	Distribution. Clytia gracilis is a circumglobal species in temperate and tropical waters (Calder 2013), and it is widely distributed in the East Atlantic, from England to South Africa (Medel & Vervoort 2000; Galea 2007). In West Africa, it has been recorded from Morocco (Patriti 1970; Ramil & Vervoort 1992 a), Mauritania (Medel & Vervoort 2000; Gil & Ramil 2017 a), Guinea-Bissau [Vervoort 1959, as L. (Phialidium) pelagica], the Republic of Guinea [Picard 1951 a; Vervoort 1959, as L. (Phialidium) pelagica], the Ivory Coast (Redier 1965, as L. gracilis), Ghana [Buchanan 1957, as L. gracilis; Vervoort 1959, as L. (Phialidium) pelagica], Cameroon, Angola (Broch 1914, as Laomedea sp. aff. gracilis) and the Vema Seamount (Gil & Ramil 2021 b). Its bathymetric distribution ranges from 0 (Peña Cantero & García Carrascosa 2002) to 1443 m (Schuchert 2001). Our material was collected at depths between 20 – 305 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F271FF76FD58FCE50C7F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: four colonies without gonothecae, of which two growing on crustaceans, one on Dynamena disticha and one on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F271FF76FD58FCE50C7F.taxon	discussion	Remarks. The more hemispherical hydrothecae with rounded, not inwardly curved marginal cusps and the morphology of the gonothecae are diagnostic, and separate this species from C. gracilis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F271FF76FD58FCE50C7F.taxon	biology_ecology	Biology. This species has usually been found as an epibiont on algae, other hydroids, bryozoans, worm tubes, other invertebrates, floating objects and in fouling communities. In the northern hemisphere, fertile material has been found throughout the year (Peña Cantero & García Carrascosa 2002). In our material, colonies were found growing on crustaceans, the hydroid D. disticha and on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F271FF76FD58FCE50C7F.taxon	distribution	Distribution. Clytia hemisphaerica is a circumglobal species (Calder 1991; Peña Cantero & García Carrascosa 2002). In West Africa, it has been recorded from Morocco (Patriti 1970), West Sahara (Leloup 1937, as Campanularia johnstoni), Mauritania (Vervoort 2006), Guinea-Bissau, the Republic of Guinea (Vervoort 1959, as C. johnstoni), the Ivory Coast (Redier 1971, as C. johnstoni), Ghana (Buchanan 1957, as C. johnstoni) and Namibia (Gili et al. 1989). Its bathymetric distribution extends from 0 to 702 m (Peña Cantero & García Carrascosa 2002). Our material was collected at depths between 24 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F24EFF76F920FCE50977.taxon	description	(Fig. 5 C – D)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F24EFF76F920FCE50977.taxon	description	149 – 152, fig. 28 e – f. — Calder, 2013: 55, fig. 15 F. Clytia gravieri: Millard, 1975: 215 – 217, fig. 71 F – H. — Marinopoulos, 1981: 176.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F24EFF76F920FCE50977.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: four colonies 25 mm high with gonothecae, of which one growing on a crustacean. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: one colony, 20 mm high without gonothecae, growing on a bryozoan. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: one colony, 9 mm high without gonothecae, growing on Idiellana pristis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F24EFF76F920FCE50977.taxon	discussion	Remarks. Although gonothecae were not found, the presence of perisarcal ridges running downward from the hydrothecal along the hydrothecal wall is diagnostic of this species (Ramil & Vervoort 1992 a). Our material represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F24EFF76F920FCE50977.taxon	biology_ecology	Biology. Clytia linearis colonizes a great variety of substrates, usually algae and other hydroids, but also rocks, bio-concretions, seagrasses, sponges, anthozoans, bryozoans, worm tubes, mollusks and barnacles (Peña Cantero & García Carrascosa 2002). In the northern hemisphere, gonothecae have been found in January, April, May and between June and November (Altuna 1994 a; Peña Cantero & García Carrascosa 2002), while in the southern hemisphere, fertile colonies were found in March and April (Migotto 1996). In our material, some colonies were found growing on crustaceans, bryozoans and on the hydroid I. pristis. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFE4F24EFF76F920FCE50977.taxon	distribution	Distribution. This species has a circumtropical distribution (Ramil & Vervoort 1992 a; Calder 2013) and it is considered a Lessepsian migrant in the Mediterranean by Boero et al. (2005). In West Africa, it has been collected from Morocco (Ramil & Vervoort 1992 a) and the Cape Verde Islands (Medel & Vervoort 2000). Its bathymetric distribution ranges from 0 (Peña Cantero & García Carrascosa 2002) to 200 m (Marinopoulos 1981). Our material was collected at depths between 20 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDBF24EFF76FC28FCE50DCE.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 10 colonies without gonothecae, of which four growing on Idiellana pristis, three on Eudendrium capilllare, two on unidentified hydroids and one on a bryozoan. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: six colonies without gonothecae, of which five growing on bryozoans and one on Halecium delicatulum. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: one colony without gonothecae, growing on a bryozoan. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: seven colonies without gonothecae growing on Halecium beanii. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: one colony without gonothecae growing on Halecium halecinum.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDBF24EFF76FC28FCE50DCE.taxon	discussion	Remarks. This is a well-known species that requires no further comments.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDBF24EFF76FC28FCE50DCE.taxon	biology_ecology	Biology. Clytia paulensis has been found growing on algae and on a wide range of invertebrates, such as polychaete tubes, bryozoans, ascidians, mollusk shells, anthozoans, gastropods and other hydroids (Peña Cantero & García Carrascosa 2002; Vervoort 2006; Galea 2007; Gil et al. 2020). In the northern hemisphere, fertile material has been found from April to August (Peña Cantero & García Carrascosa 2002), and propagulae have been found in October by Boero & Fresi (1986). Colonies studied by us were found growing on hydroids and bryozoans. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDBF24EFF76FC28FCE50DCE.taxon	distribution	Distribution. This species has a circumglobal distribution (Medel & Vervoort 2000; Galea 2007). Its distribution in West Africa has been documented recently by Gil et al. (2020). Its bathymetric range ranges from 0 to 574 m (Ramil 1988; Gil et al. 2020). Our material was collected at depths between 21 – 58 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24FFF76FE85FDB50F0E.taxon	description	(Fig. 5 E – F)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24FFF76FE85FDB50F0E.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 131, 11 º 34 ' 07 " – 11 º 33 ' 13 " N, 17 º 11 ' 25 " – 17 º 11 ' 31 " W, 102 – 103 m, 23 - X- 2008: two colonies, 14 – 27 mm high, with female gonothecae. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony, growing on a crustacean, with female gonothecae.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24FFF76FE85FDB50F0E.taxon	discussion	Remarks. The shape of the female gonothecae, with the distal end bent downwards over the laterally-set aperture, is diagnostic for the species. Our finding represents the first record of L. calceolifera for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24FFF76FE85FDB50F0E.taxon	biology_ecology	Biology. This species has been found growing on algae, sponges, barnacles (Ramil 1988) and mollusk shells (Ramil 1988; Medel & Vervoort 2000). In the northern hemisphere, colonies with gonothecae have been found in February, April, May – August, and October (Fey 1969; Ramil 1988; Cornelius 1995 b), while in the southern hemisphere, fertile colonies were found in December (Cornelius 1995 b). In our material, one colony was growing on a crustacean, and gonothecae were observed in October and, for the first time, in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24FFF76FE85FDB50F0E.taxon	distribution	Distribution. Laomedea calceolifera is widely distributed in the East Atlantic, from the Arctic Seas to South Africa, including the Mediterranean, and in the West Atlantic, from Canada to Brazil (Ramil 1988; Medel & Vervoort 2000). The species has also been recorded from the Pacific coast of USA (Leloup 1960) and as an introduced species in Japan (Chaplygina 1993). In West Africa, it has been recorded only from the Cape Verde Islands (Medel & Vervoort 2000; Vervoort 2006) and Cape Town in South Africa (Millard 1975). Its bathymetric distribution extends from the intertidal (Ramil 1988) to 1875 m (Zvyagintsev et al. 2010). Our material was collected at depths between 24 – 103 m. Genus Obelia Péron & Lesueur, 1810	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24CFF76FACFFC930987.taxon	description	12. — Peña Cantero & García Carrascosa, 2002: 159 – 161, fig. 31 A. — Vervoort, 2006: 272 – 273. Obelia bifurcata: Billard, 1906 a: 71. Laomedea bicuspidata: Vervoort, 1946: 344 – 345, fig. 10 A – B. — Buchanan, 1957: 359. Obelia bicuspidata: Patriti, 1970: 36, fig. 46. Obelia oxydentata: Picard, 1951 a: 110.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24CFF76FACFFC930987.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 134, 11 º 28 ' 17 " – 11 º 29 ' 11 " N, 17 º 13 ' 12 " – 17 º 13 ' 22 " W, 374 – 385 m, 23 - X- 2008: one colony 36 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 142 11 º 14 ' 17 " – 11 º 13 ' 22 " N, 17 º 13 ' 07 " – 17 º 13 ' 12 " W, 335 – 393 m, 25 - X- 2008: two colonies, 25 – 35 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: two colonies, 21 – 139 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: eight colonies without gonothecae, 4 – 30 mm high, of which one growing on Aglaophenia lophocarpa, one on Lytocarpia myriophyllum, one on Diphasia margareta, one on a worm tube and one on a bryozoan. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: two colonies, 35 – 36 mm high with gonothecae, substrate unknown. CCLME 2012 - 404, stn SL- 04, 10 º 48 ’ 29 ’’ N, 16 º 34 ’ 57 ’’ W, 32 m, 18 - V- 2012: two colonies up to 20 mm high without gonothecae, both growing on Eudendrium sp.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24CFF76FACFFC930987.taxon	discussion	Remarks. The large and deep, campanulate hydrothecae provided with about 10 bicuspidate cups on the hydrothecal rim are diagnostic for this species.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24CFF76FACFFC930987.taxon	biology_ecology	Biology. Obelia bidentata colonizes a great variety of substrates, such as rocks, bio-concretions, algae, seagrasses, hydrozoans, bryozoans, worm tubes, mollusk shells (sometimes inhabited by hermit crabs), isopods, cirripedes, ascidians, wreck hulls and fouling communities (Cornelius 1995 b; Peña Cantero & García Carrascosa 2002). In the northern hemisphere, gonothecae have been found in February (Vervoort 1959; Gili et al. 1989) and between May and December (Peña Cantero & García Carrascosa 2002; Gil & Ramil 2017 a). In our material, colonies were found growing on the hydroids A. lophocarpa, L. myriophyllum, D. margareta and Eudendrium sp., as well as on worm tubes and bryozoans. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDAF24CFF76FACFFC930987.taxon	distribution	Distribution. This species has mainly a circumglobal distribution in tropical and temperate waters (Peña Cantero & García Carrascosa 2002; Gil & Ramil 2017 a), but it has also been recorded from the Southern Ocean (Peña Cantero 2004). In West Africa, it has been collected from Morocco (Patriti 1970), Western Sahara (Vervoort 1946, as Laomedea bicuspidata), Mauritania (Billard 1906 a, as Obelia bifurca; Medel & Vervoort 2000; Gil & Ramil 2017 a), the Cape Verde region (Medel & Vervoort 2000), Senegal (Picard 1951 a, as Obelia oxydentata), Gambia [Vervoort 1959, as L. (Obelia) bicuspidata], Guinea-Bissau [Vervoort 1959, as L. (Obelia) bicuspidata; Gili et al. 1989], Ghana [Buchanan 1957, as L. bicuspidata; Vervoort 1959, as L. (Obelia) bicuspidata] and Nigeria [Vervoort 1959, as L. (Obelia) bicuspidata]. Its bathymetric distribution extends from 0.5 (Calder 1991) to 2600 m (Vervoort 2006). Our material was collected at depths between 32 – 385 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD9F24DFF76FBB8FC910BE3.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: nine colonies (one with gonothecae), up to 10 mm high, of which six growing on crustaceans, one on Diphasia digitalis and one on Clytia gracilis. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 10 colonies without gonothecae, 5 – 12 mm high, of which seven growing on bryozoans and one on Idiellana pristis. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: two colonies without gonothecae growing on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD9F24DFF76FBB8FC910BE3.taxon	discussion	Remarks. The campanulate hydrothecae with a slightly polygonal margin (in apical view), marked by indistinct longitudinal plicae, and the presence of gonothecae allowed an accurate identification of this species.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD9F24DFF76FBB8FC910BE3.taxon	biology_ecology	Biology. This species has been found growing on rocks, algae, seagrasses, hydroids and a wide range of other invertebrates, such as sponges, anthozoans, bryozoans, polychaetes, mollusks, and crustaceans (Medel & Vervoort 2000; Peña Cantero & García Carrascosa 2002). It has also been found on swimming animals, such as fish, turtles and even parasitic copepods on fish (Cornelius 1995 b). In the northern hemisphere, fertile material has been found throughout the year (Peña Cantero & García Carrascosa 2002). In our material, colonies were found growing on the hydroids C. gracilis, D. digitalis and I. pristis, as well as on crustaceans and bryozoans. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD9F24DFF76FBB8FC910BE3.taxon	distribution	Distribution. Obelia dichotoma is a species with a circumglobal distribution (Gil & Ramil 2021 b). In West Africa, it has been recorded from Morocco (Billard 1906 b, as Clytia longicyatha; Patriti 1970; Ramil & Vervoort 1992 a), Mauritania (Billard 1906 b, as C. longicyatha; Billard 1931 b, as Obelia hyalina; Medel & Vervoort 2000; Gil & Ramil 2017 a), Western Sahara (Leloup 1937, as L. dichotoma), the Cape Verde Islands (Rees & Thursfield 1965; Medel & Vervoort 2000), Senegal (Picard 1951 a), Gambia [Vervoort 1959, as L. (Obelia) dichotoma], Guinea-Bissau [Vervoort 1959, as L. (Obelia) dichotoma; Gili et al. 1989], Senegal, Angola [Vervoort 1959, as L. (Obelia) dichotoma], Ghana (Buchanan 1957), São Thomé (Broch 1914, as L. dichotoma) and the Vema Seamount (Gil & Ramil 2021 b). Its bathymetric distribution ranges from the intertidal (Cornelius 1995 b; Medel & Vervoort 2000) to 540 m (Vervoort 2006). Our colonies were collected at depths between 24 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD8F24DFF76FE5CFC930D19.taxon	description	(Fig. 6 A – C)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD8F24DFF76FE5CFC930D19.taxon	description	Carrascosa, 2002: 156, fig. 30 A – B. Obelia dichotoma: Ritchie, 1907: 502 – 503.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD8F24DFF76FE5CFC930D19.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 181, 10 º 14 ' 20 " – 10 º 13 ' 43 " N, 17 º 02 ' 14 " – 17 º 01 ' 34 " W, 223 – 224 m, 1 - XI- 2008: one colony 12 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: nine colonies (one with gonothecae), 13 – 21 mm high, of which two growing on crustaceans and another one on Idiellana pristis. Additional material. Mauritania, CCLME 2012 - 404, stn SL- 13, 16 º 19 ’ 51 ’’ N, 16 º 36 ’ 51 ’’ W, 34 m, 30 - V- 2012: several colonies 9 − 35 mm high, some with gonothecae. CCLME 2012 - 404, stn SL- 20, 19 º 18 ’ 22 ’’ N, 16 º 44 ’ 50 ’ W, 30 m, 08 - VI- 2012: three colonies (one with gonothecae), 20 − 30 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD8F24DFF76FE5CFC930D19.taxon	discussion	Remarks. Vervoort (1959) included this species in the genus Laomedea due to the presence (in the preserved material) of putative sessile heteromedusoid gonophores in the female gonotheca and apparently styloid gonophores in the male. However, we observed fully formed medusae within the gonothecae in our material from station SL- 13 (Fig. 6 C). The development of the gonophores as free medusae is a diagnostic feature of the genus Obelia, but not of Laomedea, in which the gonophores develop as fixed sporosacs (Bouillon et al. 2006). This finding implies the placement of this species within Obelia, under the binomen Obelia pseudodichotoma (Vervoort, 1959) comb. nov. Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD8F24DFF76FE5CFC930D19.taxon	biology_ecology	Biology. This species has been found growing on Sertularelloides cylindritheca (Allman, 1888) and ascidians (Vervoort 1959; Peña Cantero & García Carrascosa 2002). In the northern hemisphere, fertile material has been collected in January, March−August and in December (Vervoort 1959; Vervoort 1966; Medel & Vervoort 2000; Peña Cantero & García Carrascosa 2002; Gil & Ramil 2017 a). In our material, some colonies were growing on I. pristis and on crustaceans. Gonothecae were found in November for the first time in this species.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD8F24DFF76FE5CFC930D19.taxon	distribution	Distribution. Obelia pseudodichotoma comb. nov. is an East-Atlantic species distributed from the Bay of Biscay to Ghana with one record from the West Mediterranean, where it seems restricted to the Alboran Sea (Álvarez-Claudio 1993; Peña Cantero & García Carrascosa 2002). The species is mainly known from the West African coast, where it has been recorded from Mauritania (Gil & Ramil 2017 a), the Cape Verde Islands (Ritchie 1907), Senegal [Vervoort 1959, as L. (Eulaomedea) pseudodichotoma], the Ivory Coast (Redier 1971) and Ghana (Vervoort 1959). Its bathymetric distribution ranges from 15 (Peña Cantero & García Carrascosa 2002) to 230 m (Gil & Ramil 2017 a). Our material was collected at depths between 24 – 224 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF24BFF76FE85FC930E9D.taxon	description	(Fig. 6 D – E)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF24BFF76FE85FC930E9D.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: one colony with female gonothecae, growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony with female gonothecae; substrate unknown. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: 20 colonies (six with male gonothecae, seven with female gonothecae), 35 – 255 mm high, of which one growing on a polychaete tube.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF24BFF76FE85FC930E9D.taxon	discussion	Remarks. In the material studied here, some colonies from the station BS 216 were found growing on other colonies of H. beanii. This phenomenon was described by Millard (1973) as auto-epizoism, and was documented in some plumulariid and lafoeid hydroids.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF24BFF76FE85FC930E9D.taxon	biology_ecology	Biology. This species has been found growing on algae, rocks, concretions, barnacles, echinoderms, hydroids and the coral D. pertusum (Gravili et al. 2015; Gil et al. 2020). In the northern hemisphere, gonothecae have been observed throughout the year (Cornelius 1975; Gil & Ramil 2017 a), while in the southern hemisphere, fertile material was observed in January, February, May and October (Ralph, 1958; Schuchert 2005). In our material, colonies were found growing on L. myriophyllum and a polychaete tube. Gonothecae were observed in October and November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF24BFF76FE85FC930E9D.taxon	distribution	Distribution. Halecium beanii is a circumglobal species (Medel & Vervoort 2000; Gil et al. 2020). Its distribution in West Africa has been recently revised by Gil et al. (2020). This species has a wide bathymetric distribution, ranging from 0 to 1134 m depth (Millard 1978). Our material was collected at depths between 24 – 305 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF248FF76FAB5FC910E5F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: six colonies without gonothecae, of which two growing on Idiellana pristis, one on Tridentata loculosa and one on a bryozoan. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: two colonies 10 mm high, without gonothecae, growing on bryozoans. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 47 colonies (one with male and two with female gonothecae), 4 – 16 mm high, of which 45 growing on bryozoans. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: five colonies without gonothecae, 7 – 24 mm high, of which three growing on bryozoans. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: 13 colonies without gonothecae, 5 – 77 mm high, of which 10 growing on bryozoans and one on Idiellana pristis. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: one colony without gonothecae growing on Sertularelloides cylindritheca.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF248FF76FAB5FC910E5F.taxon	discussion	Remarks. The presence of female gonothecae and the morphology of the colony allowed us to identify the present material as H. delicatulum. Halecium mediterraneum Weismann, 1883 was considered a synonym of H. delicatulum by Ralph (1958), Rees & Vervoort (1987), Ramil & Vervoort (1992 a) and Peña Cantero & García Carrascosa (2002). Schuchert (2005) described slight differences between colonies collected from New Zealand and the Mediterranean Sea. These differences were related to the variability of the female gonothecae, the number of eggs per gonotheca and the color and shape of the colonies, but he also pointed out that they may not be truly representative, and that the two nominal species are almost indistinguishable. Nevertheless, and mainly for biogeographical reasons, he kept the two species separate until a molecular approach clarifies their relationships. Given that almost all hydrozoan taxonomists in the last century have accepted the synonymy between H. delicatulum and H. mediterraneum, and that Schuchert’s conclusion is speculative, we prefer to keep the West African material under the name Halecium delicatulum Coughtrey, 1876.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF248FF76FAB5FC910E5F.taxon	biology_ecology	Biology. This species colonizes living substrates, such as rhizomes of Posidonia oceanica, sponges, other hydroid species, anthozoans, mollusk shells, worm tubes, bryozoans, cirripedes and ascidians (Medel & Vervoort 2000; Peña Cantero & García Carrascosa 2002). In the northern hemisphere, gonothecae were found from April to September (Peña Cantero & García Carrascosa 2002), while in the southern hemisphere, fertile colonies were found in March, June, July, August, October and November (Migotto 1996; Vervoort & Watson 2003). In our material, colonies were found growing on hydroids and bryozoans. Gonothecae were observed in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDEF248FF76FAB5FC910E5F.taxon	distribution	Distribution. Halecium delicatulum is a circumglobal species (Schuchert 2005). In West Africa, it has been collected from Morocco (Billard 1906 b, as H. gracile; Patriti 1970; Ramil & Vervoort 1992 a), Mauritania (Billard 1906 a, as H. gracile; Medel & Vervoort 2000; Gil & Ramil 2017 a), Senegal, Guinea-Bissau and Ghana (Vervoort 1959, as H. parvulum; Gili et al. 1989). Its bathymetric distribution ranges from 0 (Millard 1975) to 2250 m (Vervoort & Watson 2003). Our colonies were collected at depths between 20 – 37 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDDF246FF76FBC0FC9308CB.taxon	description	(Fig. 7 A)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDDF246FF76FBC0FC9308CB.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: five colonies (one with male gonothecae), 66 – 235 mm high, of which one growing on a worm tube. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: two colonies without gonothecae, up to 8 mm high, both growing on bryozoans. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: two colonies, 41 – 54 mm high, without gonothecae; substrate unknown. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: three colonies up to 28 mm high, without gonothecae, of which two growing on Sertularelloides cylindritheca. CCLME- 1110, stn BT 49, 10 º 57 ' 13 " – 10 º 58 ' 26 " N, 16 º 59 ' 29 " – 17 º 00 ' 29 " W, 62 m, 29 - X- 2011: one colony without gonothecae growing on a polychaete tube.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDDF246FF76FBC0FC9308CB.taxon	discussion	Remarks. The identification of this material as H. halecinum is considered tentative because none of the colonies examined had female gonothecae. Nevertheless, their morphology is consistent with that described for this species by Cornelius (1995 a) and Schuchert (2005), and at the same time different from the material with female gonothecae, which is undoubtedly identified as H. beanii in this report. Some of the colonies showed ‘ extensible polyps’, similar to those described by Gravier-Bonnet (2008) in her study of the polymorphism in hydroids, whose functions are probably defensive, excretory and perhaps sensory. Our material represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDDF246FF76FBC0FC9308CB.taxon	biology_ecology	Biology. This species has been reported colonizing a great variety of substrates, such as bryozoans, sponges, polychaete tubes, bivalves, stones and other hydroids (Cornelius 1995 a; Medel & Vervoort 2000). In the northern hemisphere, fertile material has been collected from April to July, September, November and December (Cornelius 1975; Medel & Vervoort 2000; Schuchert 2005; Gil & Ramil 2017 a), while in the southern hemisphere, gonothecae were observed in July (Millard 1966 a). In our material, some colonies were found growing on worm tubes, bryozoans and the hydroid S. cylindritheca. One colony with gonothecae was found in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFDDF246FF76FBC0FC9308CB.taxon	distribution	Distribution. Halecium halecinum is an almost cosmopolitan species (Medel & Vervoort 2000; Schuchert 2005), but it was not included among the hydroid fauna of the Southern Ocean (Peña Cantero 2004). In West Africa, it has been recorded from Morocco (Patriti 1970; Medel & Vervoort 2000), Mauritania (Medel & Vervoort 2000; Gil & Ramil 2017 a), the Cape Verde Islands (Medel & Vervoort 2000), Senegal, Gambia (Vervoort 1959) and the Ivory Coast (Redier 1965, 1971). Its bathymetric distribution extends from the littoral zone down to 1387 m (Boero & Fresi 1986; Gil & Ramil 2017 a). Our material was collected at depths between 20 – 306 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD3F246FF76FD74FCE50D7D.taxon	description	(Fig. 7 B)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD3F246FF76FD74FCE50D7D.taxon	description	618 – 620, fig. 7. Halecium nanum: Medel & Vervoort, 2000: 18 – 21, fig. 4.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD3F246FF76FD74FCE50D7D.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 12 colonies without gonothecae, up to 43 mm high, of which three growing on Diphasia digitalis, one on Eudendrium capillare, one on Idiellana pristis and one on a worm tube. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: six colonies (five with female gonothecae), up to 8 mm high, all growing on bryozoans. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: five colonies (two with female gonothecae and one with male gonothecae), up to 5 mm high, of which four growing on bryozoans and one on Idiellana pristis. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: four colonies with male gonothecae; all growing on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD3F246FF76FD74FCE50D7D.taxon	discussion	Remarks. As described by Vervoort (1959), our colonies have geniculate stems and, hydrocladia arising in a single plane.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD3F246FF76FD74FCE50D7D.taxon	biology_ecology	Biology. Halecium lankesterii has been found growing on stones, algae, sponges, other hydroids species, anthozoans, bryozoans, worm tubes, bivalves and crustaceans (Vervoort 1959; Cornelius 1995 a; Peña Cantero & García Carrascosa 2002). In the northern hemisphere, fertile material has been found in April and between June and November (Peña Cantero & García Carrascosa 2002; Schuchert 2005). In our material, the colonies were found growing mainly on bryozoans, but also on other hydroids and worm tubes. Both female and male gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD3F246FF76FD74FCE50D7D.taxon	distribution	Distribution. This species has an East-Atlantic distribution, occurring from the English Channel and North Sea to South Africa (Schuchert 2005), with a record from Mozambique (Millard 1975). In Northwest Africa, it has been recorded from Guinea-Bissau and the Republic of Guinea (Vervoort 1959; Gili et al. 1989). Its bathymetric distribution extends from 0 to 167 m (Millard 1975; Gili et al. 1989). Our material was collected at depths between 20 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F247FF76FF35FCE50E20.taxon	description	(Fig. 7 C – D)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F247FF76FF35FCE50E20.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: four colonies without gonothecae, up to 36 mm high, of which two growing on stones, one on Eudendrium capillare and one on Diphasia digitalis. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: two colonies, 26 – 75 mm high, both with gonothecae; substrate unknown. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: one colony 30 mm high, without gonothecae; substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F247FF76FF35FCE50E20.taxon	discussion	Remarks. Our material agrees with the descriptions of Billard (1934), Ramil & Fernández Pulpeiro (1991) and Altuna (1994 b). In agreement with the latter, the female gonothecae had only one hydrothecal aperture instead of two, as described by Medel et al. (1998). This is the first record of H. liouvillei for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F247FF76FF35FCE50E20.taxon	biology_ecology	Biology. This species has been found growing on a great variety of substrates, such as bryozoans, worm tubes, shells, ascidians, gorgonians and other hydroids (Medel et al. 1998). In the northern hemisphere, gonothecae have been found in February (Medel et al. 1998) and from August to November (Leloup 1937; Altuna 1994 b; Ramil et al. 1998). In our material, colonies were found growing on stones and on the hydroids E. capillare and D. digitalis. Two colonies with gonothecae were collected in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F247FF76FF35FCE50E20.taxon	distribution	Distribution. Halecium liouvillei is an East-Atlantic species distributed from North and Northwest Spain (Ramil & Fernández Pulpeiro 1991; Altuna 1994 b) to the Gold Coast (Buchanan 1957). Its bathymetric distribution ranges from 0 to 80 m (Altuna 1994 b; Medel et al. 1998). In West Africa, it has been recorded from Morocco (Billard 1934; Patriti 1970), Western Sahara (Leloup 1937; Vervoort 1946) and the Gold Coast (Buchanan 1957). Our material was collected at depths between 21 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F244FF76FB1DFC930F1B.taxon	description	(Fig. 7 E – F)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F244FF76FB1DFC930F1B.taxon	description	fig. 15. — Vervoort, 2006: 254. — Gil et al., 2020: 427 – 428.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F244FF76FB1DFC930F1B.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 131, 11 º 34 ' 07 " – 11 º 33 ' 13 " N, 17 º 11 ' 25 " – 17 º 11 ' 31 " W, 102 – 103 m, 23 - X- 2008: one colony growing on a worm tube, without gonothecae; substrate unknown. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 320 colonies (90 with male and female gonothecae), up to 6 mm high, of which 101 growing on Idiellana pristis, 54 on bryozoans, 35 on Eudendrium capillare, 23 on Diphasia digitalis, 15 on unidentified hydroids, 10 on Tridentata loculosa, seven on Garveia nutans, five on Bimeria vestita, five on Tridentata turbinata, four on Halecium sp., two on Dynamena disticha, two on Thyroscyphus marginatus, one on Eudendrium ramosum, one on Halecium delicatulum, one on Tridentata marginata and one on Clytia gracilis. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: one colony without gonothecae, growing on Idiellana pristis. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: one colony without gonothecae, growing on Idiellana pristis. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: one colony without gonothecae, growing on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F244FF76FB1DFC930F1B.taxon	discussion	Remarks. Halecium sibogae marocanum was described from Morocco by Billard (1934), who already noted some morphological differences with his Indonesian Halecium sibogae Billard, 1929. In addition to some differences in the size of the hydrothecae between the species and the subspecies (see Ramil & Vervoort 1992 a: 88), he also noted longer internodes, larger primary hydranthophores and hydrothecae with a more everted rim in H. sibogae marocanum. Also, the internode arrangement in the latter seems to be more geniculate than that observed in H. sibogae (Billard 1934: 229). In recent years, the description of fertile materials revealed new differences between the gonothecae of the two forms. In H. sibogae marocanum the male gonothecae are globular, smooth-walled, with two more or less developed apical elevations, between which is situated the aperture at the end of a short cone (Ramil & Vervoort 1992 a). The female gonothecae have an oval-conical shape and also show the same characteristic opening flanked by two elevations (Medel & Vervoort 2000, fig. 15 c; Peña Cantero & García Carrascosa 2002, fig. 15 f). On the other hand, in H. sibogae, gonothecae of both sexes variably develop triangular crests along their perimeter, they are slightly compressed fronto-dorsally, and appear to be composed of two distinct valves fused along their perimeter (Galea, personal communication). Another difference between these two forms is their geographical distribution: H. sibogae marocanum has an Atlantic-Mediterranean occurrence (Billard 1934; Ramil & Vervoort 1992 a; Gil et al. 2020), while H. sibogae is restricted to the Pacific and Indian Oceans (Billard 1929; Gibbons & Rayland 1989; Galea, personal communication). Therefore, due to the morphological differences mentioned above, and taking into account the absence of intermediate forms and the large distributional gap between the two morphotypes, we believe that these are solid arguments to raise the subspecies H. sibogae marocanum to full species level, as Halecium marocanum Billard, 1934 nov. status. Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F244FF76FB1DFC930F1B.taxon	biology_ecology	Biology. Halecium marocanum has been found growing on a wide variety of substrates (Gil et al. 2020, as H. sibogae marocanum). In the northern hemisphere, fertile material has been reported in March, June – August (Peña Cantero & García Carrascosa 2002, as H. sibogae marocanum), November (Gil et al. 2020) and December (Gil & Ramil 2017 a, as H. sibogae marocanum). Our colonies were found growing on hydroids, worm tubes and bryozoans. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD2F244FF76FB1DFC930F1B.taxon	distribution	Distribution. This species has an Atlantic-Mediterranean distribution (Peña Cantero & García Carrascosa 2002; Gil et al. 2020). In West Africa, it was recorded from Morocco (Patriti 1970, as Halecium sibogae var. marocanum; Ramil & Vervoort 1992 a; Vervoort 2006, both as H. sibogae marocanum) to the Cape Verde Islands (Medel & Vervoort 2000, as H. sibogae marocanum). Its bathymetric distribution ranges from 16 (Peña Cantero & García Carrascosa 2002) to 756 m (Ramil et al. 1998, as H. sibogae marocanum). Our material was collected at depths between 20 – 103 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD1F245FF76FA04FCE50857.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: six colonies without gonothecae, of which three growing on bryozoans and one on a bivalve. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: 12 colonies without gonothecae, 6 – 7 mm high, of which eight growing on Idiellana pristis and one on Tridentata loculosa. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: three colonies without gonothecae, of which two growing on bryozoans and one on Idiellana pristis. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: three colonies without gonothecae, all growing on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD1F245FF76FA04FCE50857.taxon	discussion	Remarks. Halecium tenellum is a well-known and widespread species. No further discussion is needed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD1F245FF76FA04FCE50857.taxon	biology_ecology	Biology. This species has been found growing on rocks, algae and a wide range of invertebrates such as hydrozoans, bryozoans, polychaete tubes, anthozoans, sponges and D. pertusum (Peña Cantero & García Carrascosa 2002; Gil et al. 2020). In the northern hemisphere, fertile material has been found in January, April – June, October and December (Medel & Vervoort 2000; Peña Cantero & García Carrascosa 2002), while in the southern hemisphere, gonothecae were observed in April and May (Migotto 1996). The colonies studied by us were found growing on I. pristis, T. loculosa, bryozoans and bivalves. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD1F245FF76FA04FCE50857.taxon	distribution	Distribution. Halecium tenellum is a cosmopolitan species (Cornelius 1975), with some erroneous records from high latitudes of the North Atlantic (Calder 1991; Schuchert 2005). In West Africa, it has been recorded from Morocco (Patriti 1970; Ramil & Vervoort 1992 a) to Ghana (Buchanan 1957; Vervoort 1959), including the Valdivia Seamount (Gil & Ramil 2021 b). Its bathymetric distribution ranges from the intertidal zone to 1200 m (Peña Cantero & García Carrascosa 2002). Our material was collected at depths between 21 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F245FF76FCE0FD940D18.taxon	description	1996: 68, fig. 13 a. — Grohman et al., 2003: 14. — Calder & Kirkendale, 2005: 485. Sertularelloides cylindritheca: Moura, 2020: 111 – 115, fig. 22 a – b.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F245FF76FCE0FD940D18.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 143, 11 º 15 ' 35 " – 11 º 16 ' 30 " N, 17 º 09 ' 49 " – 17 º 09 ' 49 " W, 95 – 96 m, 25 - X- 2008: one colony, 55 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 199, 10 º 16 ' 49 " – 10 º 17 ' 29 " N, 16 º 22 ' 15 " – 16 º 22 ' 49 " W, 65 – 70 m, 4 - XI- 2008: one colony without gonothecae, substrate unknown. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: five colonies, 105 – 220 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 226, 11 º 22 ' 11 " – 11 º 21 ' 55 " N, 17 º 02 ' 30 " – 17 º 01 ' 54 " W, 35 – 37 m, 9 - XI- 2008: 44 colonies, 70 – 220 mm high without gonothecae, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F245FF76FCE0FD940D18.taxon	discussion	Remarks. Sertularelloides cylindritheca is a well-known species, widely distributed in West Africa. No further discussion is necessary.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F245FF76FCE0FD940D18.taxon	biology_ecology	Biology. This species has been found growing on a great variety of invertebrates (Gil & Ramil 2023 b). In the northern hemisphere, colonies with gonothecae have been found in January, and August – September (Billard 1931 a; Vervoort 1959, both as Sertularella cylindritheca), while in the southern hemisphere, gonothecae were found in March, May, and between July and October (Migotto 1996, as Sertularella cylindritheca; Moura 2020; Gil & Ramil 2023 b).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F245FF76FCE0FD940D18.taxon	distribution	Distribution. Sertularelloides cylindritheca is an amphi-Atlantic species (Gil & Ramil 2023 b). In West Africa it has been recorded from Morocco (Billard 1906 a; Patriti 1970, both as Sertularella cylindritheca) to Gabon (Gil & Ramil 2023 b). Its bathymetric distribution ranges from 0 (Grohman et al. 2003) to 614 m depth (Moura, 2011). Our material was collected at depths between 35 – 96 m. Genus Thyroscyphus Allman, 1877	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F242FF76F821FC91098C.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: nine colonies without gonothecae, up to 78 mm high, of which one colony growing on a worm tube. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: two colonies, up to 127 mm high without gonothecae, substrate unknown. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: seven colonies, 22 – 130 mm high without gonothecae, substrate unknwon. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: eight colonies, 28 – 362 mm high without gonothecae, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F242FF76F821FC91098C.taxon	discussion	Remarks. Our material conforms to that described by Vervoort (1959, as C. marginatus). We found very large colonies (up to 362 mm in height), which are larger than those described by Calder (2013) and Allman (1877). Our finding represents also the first record of T. marginatus for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F242FF76F821FC91098C.taxon	biology_ecology	Biology. This species has been found growing on worm tubes (Vervoort 1959), rocks (Calder 1991), calcareous algae and barnacles (Medel & Vervoort 1998). In the northern hemisphere, gonothecae have been found in June (Medel & Vervoort 1998), July and August (Calder 1991). In our material, one colony was found growing on a worm tube. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD0F242FF76F821FC91098C.taxon	distribution	Distribution. Thyroscyphus marginatus is an amphi-Atlantic species (Calder 2013). In West Africa, it has been recorded from the Cape Verde Islands (Medel & Vervoort 1998), the Republic of Guinea, Sierra Leone (Vervoort 1959, as Cnidoscyphus marginatus) and Ghana (Buchanan 1957; Vervoort 1959; both as C. marginatus). Its bathymetric distribution ranges from 0 (Medel & Vervoort 1998) to 90 m (Calder 1991). Our colonies were collected at depths between 21 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD7F243FF76FB01FC930BBB.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: two colonies without gonothecae, growing on worm tubes. BISSAU- 0810, stn BS 142, 11 º 14 ' 17 " – 11 º 13 ' 22 " N, 17 º 13 ' 07 " – 17 º 13 ' 12 " W, 335 – 393 m, 25 - X- 2008: one colony 56 mm high, without gonothecae, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 16 colonies without gonothecae, 7 – 50 mm high, of which two growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: 11 colonies 10 – 25 mm high, without gonothecae, of which three growing on worm tube. BISSAU- 0810, stn BS 173, 10 º 04 ' 52 " – 10 º 04 ' 17 " N, 16 º 34 ' 12 " – 16 º 33 ' 30 " W, 277 – 278 m, 31 - X- 2008: one colony 30 mm high, without gonothecae, growing on Nemertesia ventriculiformis. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: one colony 140 mm high, with gonothecae; substrate unknown. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: six colonies 55 – 111 mm high, without gonothecae; substrate unknown. CCLME- 1110, stn BT 54, 11 º 35 ' 33 " – 11 º 34 ' 02 " N, 17 º 18 ' 01 " – 17 º 17 ' 50 " W, 109 – 110 m, 30 - X- 2011: one colony 30 mm high, with gonothecae; substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD7F243FF76FB01FC930BBB.taxon	discussion	Remarks. Sertularella gayi is a well-known species and no further discussion is necessary.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD7F243FF76FB01FC930BBB.taxon	biology_ecology	Biology. This species has been found growing on a great variety of invertebrates and other substrates (Gil et al. 2020). In the northern hemisphere, colonies with gonothecae have been reported in March, April and between June – December (Teissier 1965; Ramil & Vervoort 1992 a; Ramil et al. 1992; Medel & Vervoort 1998; Gil et al. 2020). Some of our colonies were found growing on L. myriphyllum, N. ventriculiformis and worm tubes. Gonothecae were observed in October and November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD7F243FF76FB01FC930BBB.taxon	distribution	Distribution. This is an Atlantic-Mediterranean species [Ramil & Vervoort 1992, as Sertularella gayi gayi (Lamourux, 1821)]. Its distribution in West Africa has been recently revised by Gil et al. (2020). Its bathymetrical distribution ranges from 9 (Ramil et al. 1992) to 1200 m (Ramil & Vervoort 1992 a, as S. gayi gayi). Our material was collected at depths between 56 – 737 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD6F243FF76FDE4FC930D19.taxon	description	(Fig. 8 A)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD6F243FF76FDE4FC930D19.taxon	description	47 – 51, fig. 13. — Peña Cantero & García Carrascosa, 2002: 134 – 136, fig. 25 F – H. — Vervoort, 2006: 268 – 269. Sertularella polyzonias forma typica: Broch, 1914: 34.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD6F243FF76FDE4FC930D19.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 132, 11 º 31 ' 33 " N, 17 º 14 ' 07 " W, 23 - X- 2008: four colonies, 10 – 21 mm high, without gonothecae, of which two growing on Diphasia margareta and another two on Desmophyllum pertusum. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: seven colonies 12 – 27 mm high, without gonothecae, of which two growing on Diphasia margareta, and one on a worm tube. BISSAU- 0810, stn BS 174, 10 º 01 ' 42 " – 10 º 02 ' 16 " N, 17 º 00 ' 52 " – 17 º 01 ' 35 " W, 419 m, 31 - X- 2008: one colony 17 mm high, without gonothecae, growing on a worm tube. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony without gonothecae; substrate unknown. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: one colony 35 mm high, without gonothecae; substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD6F243FF76FDE4FC930D19.taxon	discussion	Remarks. This well-known species needs no further comment. We have reported this species for the first time from the waters of Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD6F243FF76FDE4FC930D19.taxon	biology_ecology	Biology. This species has been found growing on many different substrates, such as rocks, algae, seagrasses, sponges, hydrozoans, anthozoans, bryozoans, worm tubes, mollusk shells and cirripedes (Peña Cantero & García Carrascosa 2002). Sertularella polyzonias is capable of rapidly colonize new substrates by asexual propagation, thus minimizing losses caused by trawling (Henry et al. 2006). In the northern hemisphere, fertile material has been found throughout the year (Peña Cantero & García Carrascosa 2002; Gravili et al. 2015), while in the southern hemisphere, gonothecae were observed in January (Gil & Ramil 2021 b). In our material, some colonies were found growing on D. margareta, D. pertusum and worm tubes. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD6F243FF76FDE4FC930D19.taxon	distribution	Distribution. Sertularella polyzonias is an almost cosmopolitan species (Gravili et al. 2015), but it was not included by Peña Cantero (2004) within his list of Antarctic hydroids. In West Africa, it has been collected from Morocco (Billard 1906 b; Patriti 1970; Ramil & Vervoort 1992 a), Mauritania (Gil & Ramil 2017 a), the Ivory Coast (Redier 1971), Ghana (Buchanan 1957), Angola (Broch 1914) and the Vema Seamount (Gil & Ramil 2021 b). Its bathymetric distribution extends from 2 (Peña Cantero & García Carrascosa 2002) to 2500 m (Fraser 1944). Our material was collected at depths between 24 – 419 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FF35FC8109B9.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 156, 10 º 22 ' 50 " – 10 º 23 ' 40 " N, 17 º 19 ' 08 " – 17 º 19 ' 08 " W, 849 – 940 m, 27 - XI- 2008: one colony 182 mm high without gonothecae, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FF35FC8109B9.taxon	discussion	Remarks. Moura et al. (2011) have demonstrated that S. gayi robusta is genetically distinct from S. gayi (Lamouroux, 1821). The replacement name Sertularella porcupine Gil, Ramil & Ansín Agís, 2020 proposed by Gil et al. (2020) for this form to avoid a supposed synonymy with S. robusta Coughtrey, 1876 proved out of scope (Galea 2023). Therefore, as pointed out by Calder & Faucci (2021), the correct name of this morphotype should be Sertularella robusta, prioritizing Allman’s (1874) authority rather than that of Coughtrey (1876). Our material is consistent with that described by Gil et al. (2020, as S. porcupine) from the Mauritanian Coral Mounds. With this record we extend the southern distribution of S. robusta in the eastern Atlantic.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FF35FC8109B9.taxon	biology_ecology	Biology. This species has been found growing on different invertebrates and even some artificial substrates (Gil et al. 2020). In the northern hemisphere, gonothecae have been reported in May, June and November (Medel & Vervoort 1998).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FF35FC8109B9.taxon	distribution	Distribution. Sertularella robusta is and East Atlantic species (Gil et al. 2020). In West Africa, it has been recorded from Morocco, Mauritania and the Cape Verde (Ramil & Vervoort 1992 a; Medel & Vervoort 1998; Gil & Ramil 2017 a, all as S. gayi robusta). Its bathymetric distribution ranges from 120 to 1003 m (Calder & Vervoort 1998; Gil & Ramil 2017 a, both as S. gayi robusta). Our material was collected at depths between 849 – 940 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FBEAFD6E0CD0.taxon	description	(Fig. 8 B)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FBEAFD6E0CD0.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: one colony without gonothecae; substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FBEAFD6E0CD0.taxon	discussion	Remarks. Sertularella undulitheca is easily identifiable due to the morphology of its hydrothecae. Our material agrees with that described by Gil & Ramil (2023 b) and represents the first record of this species for Guinea-Bissau. No further discussion is necessary.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FBEAFD6E0CD0.taxon	biology_ecology	Biology. This species has been found growing on stones and on Aglaophenia willasseni Gil & Ramil, 2021 (Gil & Ramil 2023 b). In the northern hemisphere, fertile material has been found in January (Vervoort 1959), while in the southern hemisphere, gonothecae were observed in June (Gil & Ramil 2023 b).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F241FF76FBEAFD6E0CD0.taxon	distribution	Distribution. Sertularella undulitheca has been recorded from Guinea-Bissau, the Republic of Guinea, Ghana (Vervoort 1959), Sao Tome and Principe, and Gabon (Gil & Ramil 2023 b). Its bathymetric distribution ranges from 18 to 359 m depth (Gil & Ramil 2023 b). Our colony was collected at a depth of 24 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F25EFF76F8DDFDFC0EBB.taxon	description	(Fig. 8 C)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F25EFF76F8DDFDFC0EBB.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 48 colonies (two with gonothecae), of which four growing on bryozoans, four on Idiellana pristis, three on Eudendrium capillare, three on Diphasia digitalis, one on Eudendrium ramosum and one on a bivalve. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: seven colonies 12 – 42 mm high, without gonothecae, of which two growing on Idiellana pristis, one on Bimeria vestita and one on a bivalve. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: four colonies 14 – 22 mm high, without gonothecae, of which two growing on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F25EFF76F8DDFDFC0EBB.taxon	discussion	Remarks. Amphisbetia distans is a well-known species in the eastern Atlantic (Gil & Ramil 2023 b). No further discussion is necessary. Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F25EFF76F8DDFDFC0EBB.taxon	biology_ecology	Biology. This species has been found growing on different substrates, including a wide range of invertebrates (Peña Cantero & García Carrascosa 2002, as Sertularia distans; Gil & Ramil 2023 b). In the northern hemisphere, colonies with gonothecae have been found from January to October (Teissier 1965; Ansín Agís 1992; Peña Cantero and García Carrascosa 2002, all as S. distans), while in the southern hemisphere gonothecae were observed in April (Calder et al. 2019). In our material some colonies were growing on hydroids, bryozoans and bivalves. Fertile material was found in November	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFD4F25EFF76F8DDFDFC0EBB.taxon	distribution	Distribution. Amphisbetia distans is considered as a circumtropical species (Ramil & Vervoort 1992 a, as S. distans). In West Africa, it has been recorded from Morocco (Ramil & Vervoort 1992 a, as S. distans) to South Africa (Millard 1975, as S. distans). Its bathymetric distribution ranges from 0 (Millard 1975 as S. distans; Cornelius 1995 b; as Tridentata distans) to 826 m (Ramil & Vervoort 1992 a, as S. distans). Our material was collected at depths between 24 – 29 m. Genus Diphasia L. Agassiz, 1862	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCBF25EFF76FA81FEB10CDE.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: one colony 72 mm high, without gonothecae; substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCBF25EFF76FA81FEB10CDE.taxon	discussion	Remarks. This material was previously included in Gil & Ramil’s (2017 b) study of the genus Diphasia from Northwest Africa.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCBF25FFF76F940FC890857.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: one colony 12 mm high with gonothecae; unknown substrate.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCBF25FFF76F940FC890857.taxon	discussion	Remarks. Our material is consistent with that described by Gil & Ramil (2017 b), and represents the first record of D. alata for Guinea-Bissau, and the southernmost record in West Africa.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCBF25FFF76F940FC890857.taxon	biology_ecology	Biology. This species has been reported growing on worm tubes, bivalve shells and hydroids (Browne 1907; Ritchie 1910; Ramil & Vervoort 1992 a; Medel & Vervoort 1998) and soft bottoms (Gil & Ramil 2017 b). In the northern hemisphere, colonies with gonothecae have been found between April and September, and in December (Browne 1907; Billard 1931 a; Teissier 1965; Ramil & Vervoort 1992 a; Medel & Vervoort 1998; Gil & Ramil 2017 b).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCBF25FFF76F940FC890857.taxon	distribution	Distribution. Diphasia alata is an East-Atlantic species. In West Africa, it has been recorded from Morocco to Mauritania (Gil & Ramil 2017 b). Its bathymetric distribution ranges from 7 m (Marine Biological Association 1957) to 1024 m (Gil & Ramil 2017 b). The colony studied by us was collected at a depth of 79 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCAF25FFF76FDC8FEB10FA0.taxon	description	2003: 166, fig. 25. non Diphasia digitalis: Vervoort, 1972: 99 – 101, fig. 29.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCAF25FFF76FDC8FEB10FA0.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 984 colonies (22 with gonothecae), 10 – 140 mm high, of which 41 growing on Idiellana pristis, 18 on worm tubes, 12 on bryozoans, five on crustaceans, four on bivalves, three on Tridentata marginata, one on Eudendrium ramosum and one on Halecium lankesteri. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: 78 colonies (16 with gonothecae), 15 – 167 mm high, of which one colony growing on Idiellana pristis and another one on a bryozoan. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 12 colonies (one with gonothecae), 25 – 103 mm high; substrate unknown. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: 38 colonies without gonothecae, 21 – 128 mm high, of which four growing on Idiellana pristis and two others on bryozoans. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: 28 colonies (one with gonothecae), 27 – 125 mm high, of which two growing on bryozoans, one on an unidentified hydroid, one on Idiellana pristis, and one on Thyroscyphus marginatus. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: one colony 62 mm high without gonothecae, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCAF25FFF76FDC8FEB10FA0.taxon	discussion	Remarks. This material was previously included in Gil & Ramil’s (2017 b) study of the genus Diphasia from Northwest Africa.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCAF25CFF76F99DFD87082E.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 132, 11 º 31 ' 33 " N, 17 º 14 ' 07 " W, depth unknown, 23 - X- 2008: five colonies without gonothecae, 5 – 60 mm high, of which four growing on worm tubes. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: seven colonies (one with male gonothecae), 29 – 63 mm high, of which six growing on worm tubes and one on coral. BISSAU- 0810, stn BS 134, 11 º 28 ' 17 " – 11 º 29 ' 11 " N, 17 º 13 ' 12 " – 17 º 13 ' 22 " W, 374 – 385 m, 23 - X- 2008: four colonies 64 – 115 mm high without gonothecae; substrate unknown BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: eight colonies without gonothecae, 4 – 83 mm high, of which one growing on Nemertesia irregularis. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 223 colonies (37 with female gonothecae and 25 with male gonothecae), 15 – 119 mm high, of which 22 growing on Lytocarpia myriophyllum, one on Nemertesia irregularis, one on Nemertesia ventriculiformis and one on a worm tube. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: five colonies (one with male gonothecae), 45 – 78 mm high, of which two growing on worm tubes. BISSAU- 0810, stn BS 173, 10 º 04 ' 52 " – 10 º 04 ' 17 " N, 16 º 34 ' 12 " – 16 º 33 ' 30 " W, 277 – 278 m, 31 - X- 2008: two colonies 67 – 50 mm high without gonothecae, unknown substrate.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCAF25CFF76F99DFD87082E.taxon	discussion	Remarks. This material was included in the work of Gil & Ramil (2017 b), who re-described the species in detail, along with a discussion on its taxonomic status. These are the first records of this species for Guinea-Bissau. Genus Dynamena Lamouroux, 1812	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25CFF76FD2DFD400D08.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 51 colonies without gonothecae, 14 – 85 mm high, of which five growing on crustaceans, four on Idiellana pristis, three on bryozoans, two on bivalves, one on Eudendrium capillare, one on Eudendrium sp. and one on Diphasia digitalis. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: one colony without gonothecae, 11 mm high, growing on Idiellana pristis. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: one colony without gonothecae, growing on bryozoan. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: three colonies without gonothecae, up to 7 mm high, growing on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25CFF76FD2DFD400D08.taxon	discussion	Remarks. Our material conforms to that studied by Gil & Ramil (2023 b). No further discussion is needed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25CFF76FD2DFD400D08.taxon	biology_ecology	Biology. This species has been found growing on a wide range of substrates (Peña Cantero & García Carrascosa 2002; Moura 2020). In the northern hemisphere, fertile material has been found in January – March, July and December, while in the southern hemisphere gonothecae have been observed in March, April and June – November (Gil & Ramil 2023 b). In our material, some colonies were found growing on hydroids, crustaceans, bryozoans and bivalves. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25CFF76FD2DFD400D08.taxon	distribution	Distribution. Dynamena disticha is a circumglobal species (Peña Cantero & García Carrascosa 2002). Its distribution in West Africa was documented by Gil & Ramil (2023 b). Its bathymetric distribution ranges from 0 (Medel & Vervoort 1998) to 250 m (Gili et al. 1989). Our material was collected at depths between 20 – 29 m. Genus Idiellana Cotton & Godfrey, 1942	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25DFF76F8D1FDF40FDB.taxon	description	(Fig. 8 D – F)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25DFF76F8D1FDF40FDB.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 189, 10 º 19 ' 32 " – 10 º 18 ' 42 " N, 15 º 30 ' 40 " – 15 º 31 ' 04 " W, 22 – 28 m, 3 - XI- 2008: eight colonies with gonothecae, 46 – 80 mm high, unknown substrate. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 1427 colonies (52 with gonothecae), 14 – 99 mm high, of which 112 growing on bryozoans, 18 on Diphasia digitalis, 10 on crustaceans, six on worm tubes, five on bivalves, one on Eudendrium capillare, one on Tridentata loculosa, one on Tridentata marginata, one on Tridentata turbinata and one on Thyroscyphus marginatus. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: 75 colonies (one with gonotheca), 17 – 100 mm high, of which two growing on bivalves, one on a worm tube and one on Diphasia digitalis. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 15 colonies without gonothecae, 17 – 100 mm high, of which one growing on a bivalve and one on a bryozoan. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: 55 colonies (27 with gonothecae), 17 – 111 mm high, of which one growing on a worm tube and another one on a crustacean. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: 59 colonies (52 with gonothecae), 18 – 170 mm high, of which one growing on a crustacean. BISSAU- 0810, stn BS 199, 10 º 16 ' 49 " – 10 º 17 ' 29 " N, 16 º 22 ' 15 " – 16 º 22 ' 49 " W, 65 – 70 m, 4 - XI- 2008: one colony without gonothecae, 27 mm high, unknown substrate.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25DFF76F8D1FDF40FDB.taxon	discussion	Remarks. In one colony from station BS 191 and two colonies from station BS 194, we observed the phenomenon of auto-epizoism, as described by Millard (1973) in other hydroids. Idiellana pristis is a well-known species in West Africa, and needs no further discussion.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25DFF76F8D1FDF40FDB.taxon	biology_ecology	Biology. This species has been found growing on rocks (Migotto 1996), dead coral and other invertebrates (Vervoort 1993; Watson 2000). In the northern hemisphere, gonothecae were found in January, February, May and July – December, while in the southern hemisphere fertile colonies were found in February, April, May, July, August and November (Gil & Ramil 2023 b). In our material, colonies were found growing on several hydroid species, bryozoans, bivalves, worm tubes and crustaceans. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC9F25DFF76F8D1FDF40FDB.taxon	distribution	Distribution. Idiellana pristis is a circumtropical species (Watson 2000; Schuchert 2003) in shallow waters, whose distribution in West Africa has been recently revised by Gil & Ramil (2023 b). Its bathymetric distribution ranges from 0 (Millard 1975) to 150 m (Vervoort 1993). Our material was collected at depths between 20 – 70 m. Genus Tridentata Stechow, 1920	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC8F25BFF76FA61FCE508BF.taxon	description	(Fig. 9 A)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC8F25BFF76FA61FCE508BF.taxon	description	71 a – g.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC8F25BFF76FA61FCE508BF.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 565 colonies without gonothecae, 8 – 95 mm high, of which 121 growing on bryozoans, 97 on Idiellana pristis, 57 on Diphasia digitalis, 13 on crustaceans, 10 on Eudendrium capillare, nine on unidentified hydroids, five on worm tubes, two on Thyroscyphus marginatus, one on Plumularia setacea and one on a bivalve. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: 38 colonies without gonothecae, 15 – 64 mm high, of which one growing on a worm tube. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 13 colonies without gonothecae, 1 – 27 mm high, of which 10 growing on bryozoans and one on Idiellana pristis. BISSAU- 0810, stn BS 194 ¸ 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: 11 colonies (three with gonothecae), 7 – 20 mm high, of which five growing on bryozoans, two on Eudendrium sp, one on Eudendrium ramosum and one on Idiellana pristis. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: 16 colonies without gonothecae, 16 – 36 mm high, of which six growing on bryozoans and two on Idiellana pristis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC8F25BFF76FA61FCE508BF.taxon	discussion	Remarks. Our material agrees with that described by Gil & Ramil (2023 b) from the Republic of Guinea. No further discussion is necessary.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC8F25BFF76FA61FCE508BF.taxon	biology_ecology	Biology. This species has been found growing on stones (Billard 1931 b, as Sertularia loculosa), algae, hydroids, bryozoans and barnacles (Vervoort 1959; Migotto 1996, both as Sertularia ligulata). In the southern hemisphere, fertile colonies have been found between January – March and June (Migotto 1996, as S. ligulata). In our material, some colonies were growing on hydroids, bryozoans, worm tubes, bivalves and crustaceans; in addition, some of them were auto-epizoic. Gonothecae were found in the northern hemisphere in November for the first time.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC8F25BFF76FA61FCE508BF.taxon	distribution	Distribution. Tridentata loculosa is a circumtropical species (Calder 2013), with a bathymetric distribution ranging from 0 (Galea 2008) to 155 m (Migotto 1996). In West Africa, it has been recorded from Guinea-Bissau (Billard 1931 a) to the Ivory Coast (Redier 1965, as S. ligulata). Our material was collected at depths between 20 – 29 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCEF258FF76FCE0FCE50B53.taxon	description	(Fig. 9 B – D)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCEF258FF76FCE0FCE50B53.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 85 colonies without gonothecae, 8 – 107 mm high, of which six growing on Diphasia digitalis, two on Idiellana pristis, two on worm tubes, two on a bryozoan and one on a bivalve. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: five colonies without gonothecae, 40 – 155 mm high, substrate unknown. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: one colony without gonothecae, 96 mm high, substrate unknown. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: four colonies without gonothecae, 55 – 75 mm high, substrate unknown. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: six colonies (five with gonothecae), 27 – 130 mm high, substrate unknown. BISSAU- 0810, stn BS 199, 10 º 16 ' 49 " – 10 º 17 ' 29 " N, 16 º 22 ' 15 " – 16 º 22 ' 49 " W, 65 – 70 m, 4 - XI- 2008: one colony without gonothecae, 81 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCEF258FF76FCE0FCE50B53.taxon	discussion	Remarks. Differences between T. marginata and Tridentata turbinata (Lamouroux, 1816) were pointed out by Calder (2013), and also discussed by Gil & Ramil (2023 b). Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCEF258FF76FCE0FCE50B53.taxon	biology_ecology	Biology. This species has been found growing on algae and rocks (Migotto 1996), stranded Thalassia sp., shipwrecks (Calder 1991), Zostera leaves (Medel & Vervoort 1998) and stranded Sargassum sp. (Calder 2013). In the northern hemisphere, fertile colonies were found in May, June, July, October and November (Medel & Vervoort 1998; Calder 2013), while in the southern hemisphere gonothecae have been found throughout the year (Migotto 1998). In our material colonies were found growing on hydroids, polychaetes, bryozoans and bivalves. Gonothecae were found in November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCEF258FF76FCE0FCE50B53.taxon	distribution	Distribution. Tridentata marginata is a circumtropical species (Migotto 1996; Vervoort & Watson 2003). In West Africa, it has been recorded from Morocco (Medel & Vervoort 1998), Mauritania (Billard 1906 a, as S. versluysi; Medel & Vervoort 1998), the Cape Verde Islands (Ritchie 1907, as S. versluysi; Medel & Vervoort 1998), Ghana (Buchanan 1957) and Congo (Leloup 1939). Its bathymetric distribution ranges from 0 (Millard 1975) to 90 m (Grohmann et al. 2003). Our material was collected at depths between 20 – 70 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF258FF76FECCFCE50EEB.taxon	description	(Fig. 9 E)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF258FF76FECCFCE50EEB.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony without gonothecae, growing on a bryozoan. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: 11 colonies without gonothecae, 4 – 9 mm high, all growing on bryozoans.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF258FF76FECCFCE50EEB.taxon	discussion	Remarks. Our material is consistent with that described by Gil & Ramil (2023 b), and represents the first record of T. rugosissima for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF258FF76FECCFCE50EEB.taxon	biology_ecology	Biology. This species has been found growing on hydrozoans, bryozoans and algae (Vannucci Mendes 1946; Migotto 1996; Galea 2008). In the northern hemisphere, fertile colonies have been found but no data information is given (Cooke 1975), while in the southern hemisphere, they have been found in April (Vannucci Mendes 1946). Our colony was found growing on a bryozoan. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF258FF76FECCFCE50EEB.taxon	distribution	Distribution. Tridentata rugosissima has a circumtropical distribution (Migotto 1996). In West Africa, it has been recorded from the Republic of Guinea (Gil & Ramil 2023 b) and Ghana (Broch 1914). Its bathymetric distribution ranges from 0 (Galea 2008) to 26 m (Gil & Ramil 2023 b). Our material was collected at depths between 20 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF259FF76FB54FC910B0F.taxon	description	(Fig. 9 F)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF259FF76FB54FC910B0F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: 107 colonies without gonothecae, 20 – 25 mm high, of which 20 growing on Idiellana pristis, 12 on Diphasia digitalis, six on bryozoans, three on crustaceans, two on Eudendrium capillare, one on Bimeria vestita, one on an unidentified hydroid and one on a bivalve. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: two colonies without gonothecae, 14 mm high, unknown substrate.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF259FF76FB54FC910B0F.taxon	discussion	Remarks. Our material is consistent with that of Gil & Ramil (2023 b) from Gabon. No further discussion is required.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCDF259FF76FB54FC910B0F.taxon	biology_ecology	Biology. Tridentata turbinata has been found growing on rocks, algae, barnacles, spines of echinoderms, polychaete tubes and hydroids (Galea & Ferry 2015; Gil & Ramil 2023 b). In the northern hemisphere, colonies with gonothecae have been found in February, April, June – August and December (Vervoort 1959; Hirohito 1995, both as S. turbinata; Galea & Ferry 2015; Humara-Gil & Cruz-Gómez 2018). In our material, some colonies were found growing on hydroids, bivalves, bryozoans and crustaceans. Distribution. This is a circumtropical species (Calder et al. 2019) from shallow waters, and its bathymetric distribution ranges from 0 (Medel and Vervoort 1998, as S. turbinata) to 50 m (Schuchert 2003). Its distribution in West Africa has been recently documented by Gil & Ramil (2023 b). Our colonies were collected at depths between 24 – 25 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF259FF76FDC8FC930C2B.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 132, 11 º 31 ' 33 " N, 17 º 14 ' 07 " W, depth unknown, 23 - X- 2008: four colonies without corbulae, 23 – 48 mm, substrate unknown. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: two colonies without corbulae growing on worm tubes. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: six colonies with corbulae, 59 – 82 mm high, of which one growing on a worm tube. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 101 colonies (two with corbulae), 24 – 153 mm high, most of them detached from the substrate, but three of them growing on Diphasia digitalis, three on Lytocarpia myriophyllum and one on a worm tube. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: 20 colonies (five with corbulae), 15 – 83 mm high, of which two growing on worm tubes, one on Diphasia margareta and one on Aglaophenia tubulifera.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF259FF76FDC8FC930C2B.taxon	discussion	Remarks. Aglaophenia lophocarpa is a well-known species in Northwest Africa and needs no further comment.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF259FF76FDC8FC930C2B.taxon	biology_ecology	Biology. This species has been found growing on a wide variety of substrates (Peña Cantero & García Carrascosa 2002; Vervoort 2006; Gil et al. 2020). In the northern hemisphere, gonothecae have been found throughout the year (Ansín Agís et al. 2001; Gil & Ramil 2017 a). Our colonies were found growing on worm tubes and other hydroid species. Corbulae were observed in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF259FF76FDC8FC930C2B.taxon	distribution	Distribution. Aglaophenia lophocarpa is a species with an amphi-Atlantic distribution (Ansín Agís et al. 2001) and a wide bathimetric distribution, from 0 – 2700 m depth (Ansín Agís et al. 2001; Vervoort 2006). In West Africa, it has been collected from Morocco (Ramil & Vervoort 1992 a) to Gabon (Gil & Ramil 2021 a). Our material was collected at depths between 23 – 737 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF257FF76F914FC810E5F.taxon	description	(Fig. 10 A – B)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF257FF76F914FC810E5F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: one colony without corbulae, 80 mm high, growing on a worm tube. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: one colony without corbulae, 130 mm high, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 37 colonies without corbulae, 11 – 157 mm high, of which one growing on a worm tube. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: 22 colonies (five with corbulae), 24 – 120 mm high, of which three growing on worm tubes.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF257FF76F914FC810E5F.taxon	discussion	Remarks. Aglaophenia tubulifera is a well-known species from the East Atlantic and no further comments are necessary. Variations in hydrothecal morphology and development of the mesial nematothecae have been documented by Ramil et al. (1998).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF257FF76F914FC810E5F.taxon	biology_ecology	Biology. This species grows mainly on other hydroid species (Eudendrium sp., Cryptolaria sp., Halecium marocanum, Streptocaulus corneliusi, Nemertesia ramosa, Polyplumaria flabellata, Pseudoplumaria sabinae, Diphasia alata, Sertularella gayi and Sertularella sp.), but also on antipatharian stalks and worm tubes (Ramil & Vervoort 1992 a; Ramil et al. 1998; Ansín Agís et al. 2001); also reported on sponges (Billard 1906 b) and rocks or similar substrates (Cornelius 1995 b). In the northern hemisphere, fertile material has been collected throughout the year, except in October and December (Ansín Agís et al. 2001; Gil & Ramil 2017 a). In our material, some colonies were found growing on worm tubes. Colonies with corbulae were found in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFCCF257FF76F914FC810E5F.taxon	distribution	Distribution. Aglaophenia tubulifera is an East-Atlantic species that penetrates the Mediterranean to the Alboran Sea (Svoboda & Cornelius 1991; Ramil & Vervoort 1992 a), with a bathymetric range extending from 8 to 1513 m (Ansín Agís et al. 2001; Gil & Ramil 2017 a). In West Africa, it has been recorded from Morocco (Billard 1906 b; Patriti 1970; Ramil & Vervoort 1992 a), Western Sahara (Billard 1906 b), Mauritania (Gil & Ramil 2017 a), the Cape Verde Islands (Svoboda 1979; Vervoort 2006) and Guinea-Bissau (Gili et al. 1989). Our material was collected at depths between 186 – 737 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F257FF76FBC0FDBD0CF9.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony without corbulae, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F257FF76FBC0FDBD0CF9.taxon	discussion	Remarks. Our material agrees with that described by Gil & Ramil (2021 a) with respect to the morphology of the colony and hydrothecae that possess lateral nematothecae with two apertures. Our material represents the first record of this species for Guinea-Bissau since its description.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F257FF76FBC0FDBD0CF9.taxon	biology_ecology	Biology. In the northern hemisphere, fertile material has been found in May, while in the southern hemisphere, gonothecae were found in May and July (Gil & Ramil 2021 a).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F257FF76FBC0FDBD0CF9.taxon	distribution	Distribution. This species has been recorded only from the Republic of Guinea and Gabon, between 31 and 359 m (Gil & Ramil 2021 a). Our material was collected at depths between 24 – 25 m. Genus Lytocarpia Kirchenpauer, 1872	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F254FF76F97DFC930FD3.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: one colony without corbulae, 225 mm high, substrate unknown. BISSAU- 0810, stn BS 134, 11 º 28 ' 17 " – 11 º 29 ' 11 " N, 17 º 13 ' 12 " – 17 º 13 ' 22 " W, 374 – 385 m, 23 - X- 2008: seven colonies (six with corbulae), 74 – 370 mm high, substrate unknown. BISSAU- 0810, stn BS 136, 11 º 28 ' 29 " – 11 º 27 ' 33 " N, 17 º 08 ' 30 " – 17 º 08 ' 33 " W, 75 – 76 m, 24 - X- 2008: one colony without corbulae, 200 mm high, substrate unknown. BISSAU- 0810, stn BS 142, 11 º 14 ' 17 " – 11 º 13 ' 22 " N, 17 º 13 ' 07 " – 17 º 13 ' 12 " W, 335 – 393 m, 25 - X- 2008: three colonies with corbulae, 50 – 180 mm high, substrate unknown. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: one colony with corbulae, 103 mm high, substrate unknown. BISSAU- 0810, stn BS 149, 11 º 06 ' 46 " – 11 º 07 ' 39 " N, 17 º 06 ' 23 " – 17 º 06 ' 40 " W, 71 m, 26 - X- 2008: four colonies without corbulae, 323 – 500 mm high, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 508 colonies (34 with corbulae), 14 – 300 mm high, of which one growing on Diphasia margareta. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: three colonies without corbulae, 80 – 190 mm high, substrate unknown. BISSAU- 0810, stn BS 172, 10 º 07 ' 45 " – 10 º 07 ' 02 " N, 16 º 34 ' 11 " – 16 º 33 ' 37 " W, 223 – 224 m, 31 - X- 2008: three colonies with corbulae, 230 – 650 mm high, substrate unknown. BISSAU- 0810, stn BS 174, 10 º 01 ' 42 " – 10 º 02 ' 16 " N, 17 º 00 ' 52 " – 17 º 01 ' 35 " W, 419 m, 31 - X- 2008: one colony with corbulae, 394 mm high, substrate unknown. BISSAU- 0810, stn BS 177, 10 º 10 ' 16 " – 10 º 11 ' 00 " N, 17 º 07 ' 21 " – 17 º 07 ' 54 " W, 382 – 387 m, 31 - X- 2008: 13 colonies (12 with corbulae), 108 – 372 mm high, substrate unknown. BISSAU- 0810, stn BS 182, 10 º 14 ' 14 " – 10 º 13 ' 22 " N, 16 º 32 ' 49 " – 16 º 32 ' 44 " W, 211 – 224 m, 1 - XI- 2008: four colonies without corbulae, 377 – 537 mm high, substrate unknown. CCLME- 1205, stn BT 306, 9 º 59 ' 41 " – 9 º 58 ' 31 " N, 16 º 49 ' 40 " – 16 º 48 ' 35 " W, 314 m, 15 - V- 2012: three colonies without corbulae, 98 – 380 mm high, substrate unknown. CCLME- 1205, stn BT 310, 10 º 28 ' 41 " – 10 º 29 ' 37 " N, 16 º 26 ' 14 " – 16 º 27 ' 37 " W, 48 – 49 m, 16 - VI- 2012: one colony without corbulae, 225 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F254FF76F97DFC930FD3.taxon	discussion	Remarks. This species is widespread in the West Atlantic and needs no further discussion.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F254FF76F97DFC930FD3.taxon	biology_ecology	Biology. This species has recently been found growing in a deep-water coral mounds habitat (Gil et al. 2020). It is a very common component of temperate waters hydroid forests (Di Camilo et al. 2013). In the northern hemisphere, corbulae have been found almost all year round, from February to November (Ansín Agís et al. 2001; Di Camilo et al. 2013). In our material, one colony was found growing on D. margareta. Corbulae were found in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC2F254FF76F97DFC930FD3.taxon	distribution	Distribution. Lytocarpia myriophyllum is a well-known species, with an amphi-Atlantic distribution (Ansín Agís et al. 2001). In West Africa, it has been recorded from Morocco (Ansín Agís et al. 2001) to Gabon (Gil et al. 2021 a). Its bathymetric range extends from 5 to 1800 m (Ramil & Vervoort 1992 a; Ansín Agís et al. 2001). Our material was collected at depths between 48 – 737 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC1F255FF76FA4AFD7908E6.taxon	description	(Fig. 10 C)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC1F255FF76FA4AFD7908E6.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: six colonies without corbulae, 1 – 150 mm high, of which one growing on a bryozoan and one on a crustacean. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: ten colonies without corbulae, 50 – 300 mm high, substrate unknown. BISSAU- 0810, stn BS 193, 10 º 21 ' 13 " – 10 º 21 ' 51 " N, 16 º 10 ' 17 " – 16 º 10 ' 56 " W, 20 – 21 m, 3 - XI- 2008: three colonies without corbulae, 39 – 143 mm high, substrate unknown. BISSAU- 0810, stn BS 194, 10 º 21 ' 59 " – 10 º 22 ' 36 " N, 16 º 13 ' 23 " – 16 º 14 ' 03 " W, 21 – 24 m, 3 - XI- 2008: two colonies without corbulae, 171 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC1F255FF76FA4AFD7908E6.taxon	discussion	Remarks. Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC1F255FF76FA4AFD7908E6.taxon	biology_ecology	Biology. This species has been found recently growing on octocorals and limestone (Calder 2019). In the north hemisphere, fertile material was found in January and June, while in the southern hemisphere it has been found between February – April and July – December (Gil & Ramil 2021 a). In our material, some colonies were found growing on bryozoans and crustaceans. Corbulae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC1F255FF76FA4AFD7908E6.taxon	distribution	Distribution. Lytocarpia tridentata is an amphi-Atlantic hydroid (Gil & Ramil 2021 a). In West Africa, it has been only recorded from the Republic of Guinea (Picard 1951 a, as Aglaophenia tridentata; Gil & Ramil 2021 a). Its bathymetric range extends from 0 to 70 m (Grohmann et al. 2003). Our material was collected at depths between 20 – 25 m. Genus Macrorhynchia Kirchenpauer, 1872	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F255FF76FD74FD910D21.taxon	description	(Fig. 10 D)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F255FF76FD74FD910D21.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: seven colonies without gonosome, 53 mm high, of which three growing on crustaceans and one on an unidentified hydroid.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F255FF76FD74FD910D21.taxon	discussion	Remarks. The small size of the colonies we studied could be related to the shallow depth at which they occurred. According to Watson (2002), colonies from shallow waters are smaller because they are under more exposed conditions than those living in deeper water. The record of M. philippina from Kei Islands, Indonesia (Schuchert 2003) is considered a possible synonym of Macrorhynchia fallax Galea & Maggioni, 2024 (original account).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F255FF76FD74FD910D21.taxon	biology_ecology	Biology. Macrorhynchia philippina is a species with a high capacity of colonization (Espino et al. 2020) and a habitat former (Chakraborty & Raghunathan 2020). It has been collected from many different types of habitats and substrates, including rocky reefs, seagrass meadows, rhodolith seabeds (Espino et al. 2020), hard substrates (Watson 2002; Cinar et al. 2006), dead gorgonians, corals and ropes (Di Camilo et al. 2010). In the northern hemisphere, fertile material has been found in June, August and October (Ansín Agís et al. 2001), while in the southern hemisphere the gonosome was observed in July (Millard 1958, as Lytocarpus philippinus). In our material, some colonies were growing on crustaceans and an unidentified hydroid.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F255FF76FD74FD910D21.taxon	distribution	Distribution. This is a circumglobal species in tropical and subtropical waters (Schuchert 2003; Di Camilo et al. 2010; Calder & Faucci 2021). In West Africa, it has been recorded from the Cape Verde (Ritchie 1907, as Lytocarpus crosslandi; Ansín Agís et al. 2001) and Guinea-Bissau (Billard 1931 a, as L. philippinus). Its bathymetric distribution ranges from 1 to 411 m (Ansín Agís et al. 2001). Our material was collected from a depth of 24 – 25 m. Genus Streptocaulus Allman, 1883	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F252FF76F83FFC930918.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: two colonies with gonothecae, 122 – 136 mm high, substrate unknown. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: two colonies (one with gonothecae), 57 – 75 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F252FF76F83FFC930918.taxon	discussion	Remarks. This is a well-known species characterized by the curvature of its hydrothecae, with a convex basal part and an almost straight distal part. No further comments are necessary. Our finding represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F252FF76F83FFC930918.taxon	biology_ecology	Biology. In the northern hemisphere, fertile material has been found between October and December (Medel & Vervoort 1995; Gil & Ramil 2017 a). Patriti (1970) found colonies with phylactocarps in material collected off Morocco, but without indication of the collection date; therefore, the reproductive period could be longer than indicated here. In our material, phylactocarps were found in October and November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC0F252FF76F83FFC930918.taxon	distribution	Distribution. Streptocaulus dollfusi is an amphi-Atlantic species that also penetrates the western Mediterranean (Ansín Agís et al. 2001). In West Africa, it has been recorded from Morocco (Billard 1934; Patriti 1970, as C. dollfusi), Mauritania (Ansín Agís et al. 2001; Gil & Ramil 2017 a), Sierra Leone and Senegal (Vervoort 1959, as C. ventricosus). Its bathymetric distribution ranges from 60 to 1513 m (Medel & Vervoort 1995; Gil & Ramil 2017 a). Our material was collected at depths between 56 – 305 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC7F253FF76FB95FC810B9F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 131, 11 º 34 ' 07 " – 11 º 33 ' 13 " N, 17 º 11 ' 25 " – 17 º 11 ' 31 " W, 102 – 103 m, 23 - X- 2008: one colony with gonothecae, 40 mm high, growing on a worm tube. BISSAU- 0810, stn BS 134, 11 º 28 ' 17 " – 11 º 29 ' 11 " N, 17 º 13 ' 12 " – 17 º 13 ' 22 " W, 374 – 385 m, 23 - X- 2008: two colonies (one with gonothecae), 13 – 20 mm high, both growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 26 colonies (two with gonothecae), 5 – 11 mm high, of which nine growing on Lytocarpia myriophyllum, six on Diphasia margareta, two on Aglaophenia lophocarpa, one on Aglaophenia tubulifera and one on Diphasia sp. CCLME- 1110, stn BT 40, 10 º 15 ' 45 " – 10 º 14 ' 39 " N, 16 º 55 ' 17 " – 16 º 54 ' 05 " W, 224 m, 27 - X- 2011: one colony with gonothecae, growing on a polychaete tube. CCLME- 1205, stn BT 313, 10 º 15 ' 41 " – 10 º 16 ' 47 " N, 16 º 55 ' 17 " – 16 º 56 ' 27 " W, 224 – 225 m, 16 - VI- 2012: one colony without gonothecae, 10 mm high, growing on a prosobranch. CCLME- 1205, stn BT 319, 10 º 35 ' 40 " – 10 º 36 ' 53 " N, 16 º 59 ' 31 " – 17 º 00 ' 30 " W, 209 m, 18 - V- 2012: one colony with gonothecae, 15 mm high, unknown substrate.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC7F253FF76FB95FC810B9F.taxon	discussion	Remarks. Our material agrees with that of Gil et al. (2020) from Mauritanian coral mounds. No further discussion is required. Recent molecular analyses have demonstrated that A. secundaria is a complex of cryptic species (Moura et al. 2018), and it would be more prudent to consider that only the Mediterranean and eastern Atlantic records are valid.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC7F253FF76FB95FC810B9F.taxon	biology_ecology	Biology. Antennella secundaria has been found growing on rocks, algae, bryozoans, hydrozoans, anthozoans, sponges, cirripedes, polychaete tubes and on bio-concretions, pebbles and D. pertusum (Peña Cantero & García Carrascosa 2002; Gil et al. 2020). Fertile material has been found in the northern hemisphere between February and December (Boero & Fresi 1986; Alvarez Claudio 1993; Medel & Vervoort 1995; Ansín Agís et al. 2001; Gil & Ramil 2017 a), while in the southern hemisphere gonothecae have been observed in February and between August and November (Millard 1968; Gravier Bonnet 1970; Vervoort & Vasseur 1977; Gravier Bonnet 1979). In our material, colonies were found growing on hydroids, prosobranchs and worm tubes. Gonothecae were observed in May and October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC7F253FF76FB95FC810B9F.taxon	distribution	Distribution. Antennella secundaria is considered as a circumglobal species (Ansín Agís et al. 2001; Gil et al. 2020), although Schuchert (1997) suggested that it may represent a species complex. In West Africa, it has been recorded from Morocco (Patriti 1970) to Gabon (Gil & Ramil 2021 a). Our material was collected at depths between 102 – 385 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F253FF76FD80FDCB0C14.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 131, 11 º 34 ' 07 " – 11 º 33 ' 13 " N, 17 º 11 ' 25 " – 17 º 11 ' 31 " W, 102 – 103 m, 23 - X- 2008: one colony without gonothecae, growing on a crustacean. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: three colonies without gonothecae, 17 mm high, of which two growing on Idiellana pristis and one on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F253FF76FD80FDCB0C14.taxon	discussion	Remarks. The morphology of the lateral nematothecae and the absence of an axillary nematotheca distinguish A. siliquosa from A. secundaria (Schuchert 1997; Ansín Agís et al. 2001).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F253FF76FD80FDCB0C14.taxon	biology_ecology	Biology. This species has been collected growing on rocks, algae, other hydroids, and a wide variety of invertebrates, such as sponges, gorgonians, bryozoans, worm tubes, cirripedes and ascidians (Gravili et al. 2015). In the northern hemisphere, fertile material has been found in March and from May to November (Ansín Agís et al. 2001; Gil & Ramil 2017 a). In our material, colonies were found growing on the hydroid I. pristis, crustaceans and bryozoans. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F253FF76FD80FDCB0C14.taxon	distribution	Distribution. Antennella siliquosa is considered as an Atlantic-Mediterranean species (Boero & Bouillon 1993; Schuchert 1997). In West Africa, it has been recorded from Morocco (Patriti 1970; Ramil & Vervoort 1992 a, as H. diaphana f. siliquosa; Ansín Agís et al. 2001), Mauritania (Ansín Agís et al. 2001; Gil & Ramil 2017 a), the Cape Verde Islands (Ansín Agís et al. 2001; Vervoort 2006), Senegal, Guinea-Bissau, the Republic of Guinea, Liberia (Vervoort 1959, as A. diaphana f. siliquosa), the Ivory Coast (Vervoort 1959, as A. diaphana f. siliquosa; Redier 1965) and Ghana (Buchanan 1957). Its bathymetric distribution ranges from the intertidal to 1387 m (Gravili et al. 2012; Gil & Ramil 2017 a). Our colonies were collected at depths between 24 – 103 m. Genus Halopteris Allman, 1877	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F250FF76F925FC810857.taxon	description	(Fig. 10 E)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F250FF76F925FC810857.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 134, 11 º 28 ' 17 " – 11 º 29 ' 11 " N, 17 º 13 ' 12 " – 17 º 13 ' 22 " W, 374 – 385 m, 23 - X- 2008: one colony without gonothecae, growing on Diphasia margareta.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F250FF76F925FC810857.taxon	discussion	Remarks. The material is morphologically in agreement with that of Gil et al. (2020) from Mauritania. This species is widespread in Northwest Africa and does not require further discussion. Our finding represents the first record of H. catharina for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F250FF76F925FC810857.taxon	biology_ecology	Biology. This species has been found growing mostly on other hydroids, as well as on a wide variety of invertebrates and algae (Ramil & Vervoort 1992 a; Ansín Agís et al. 2001; Gravili et al. 2013; Gil et al. 2020). In the northern hemisphere, colonies with gonothecae have been found in February and from April to September (Ansín Agís et al. 2001). The colony studied by us was found growing on Diphasia margareta. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC6F250FF76F925FC810857.taxon	distribution	Distribution. Halopteris catharina is a species with an amphi-Atlantic distribution (Ramil & Vervoort 1992 a; Ansín Agís et al. 2001). In West Africa, it has been recorded from Morocco (Ramil & Vervoort 1992 a), Mauritania (Gil & Ramil 2017 a) and the Cape Verde Archipelago (Ansín Agís et al. 2001; Vervoort 2006). Its bathymetric distribution ranges from 1 to 642 m (Ansín Agís et al. 2001; Gil et al. 2020). Our material was collected at depths between 374 – 385 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F250FF76FDC8FD8F0C0E.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: eight colonies without gonothecae, 5 mm high, of which two growing on bryozoans and one on Diphasia digitalis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F250FF76FDC8FD8F0C0E.taxon	discussion	Remarks. Halopteris diaphana is similar to H. alternata (Nutting, 1900), a species recorded by Ansín Agís et al. (2001) from Madeira, Canary and the Cape Verde Islands. Both species can be easily separated based on the morphology of the female gonothecae and additional differences highlighted by Ansín Agís et al. (2001). Our material, characterized by the heteromerous segmentation of the hydrocaulus, the absence of axillary nematothecae behind the cauline hydrothecae and the presence of two nematothecae on the ahydrothecate cauline internodes, corresponds to H. diaphana. Our colonies represent the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F250FF76FDC8FD8F0C0E.taxon	biology_ecology	Biology. This species has been found growing on D. digitalis (Gil & Ramil 2021 a). Colonies with gonothecae have been found in the northern hemisphere in April, June, July and September (Schuchert 1997; Ansín Agís et al. 2001), while in the southern hemisphere gonothecae have been found only in November (Schuchert 1997). In our material, some colonies were also found growing on D. digitalis and bryozoans. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F250FF76FDC8FD8F0C0E.taxon	distribution	Distribution. Halopteris diaphana is a circumtropical species whose distribution in West Africa, has been recently revised by Gil & Ramil (2021 a). Its bathymetrical distribution ranges from 0 to 240 m (Ansín Agís et al. 2001). Our material was collected at depths between 24 – 25 m. Genus Polyplumaria G. O. Sars, 1874	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F22EFF76F9CCFD390872.taxon	description	(Fig. 11 A)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F22EFF76F9CCFD390872.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 132, 11 º 31 ' 33 " N, 17 º 14 ' 07 " W, 23 - X- 2008: one colony without gonothecae, 42 mm high, substrate unknown. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: five colonies without gonothecae, 47 – 125 mm high, of which four growing on worm tubes.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F22EFF76F9CCFD390872.taxon	discussion	Remarks. Polyplumaria flabellata is a well-known species and requires no further comment. This is the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F22EFF76F9CCFD390872.taxon	biology_ecology	Biology. In the northern hemisphere, colonies with gonothecae have been found in March, May – August (Ansín Agís et al. 2001) and in December (Gil et al. 2020). In our material, some colonies were found growing on worm tubes. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFC5F22EFF76F9CCFD390872.taxon	distribution	Distribution. Polyplumaria flabellata is an East Atlantic species with a wide bathymetric distribution, ranging from 47 to 2200 m depth (Ansín Agís et al. 2001). Its distribution in West Africa has been recently documented by Gil et al. (2020). Our material was collected at depths between 733 – 737 m. Genus Pseudoplumaria Ramil & Vervoort, 1992	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22EFF76FDC8FC930CE6.taxon	description	(Fig. 11 B)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22EFF76FDC8FC930CE6.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 182, 10 º 14 ' 14 " – 10 º 13 ' 22 " N, 16 º 32 ' 49 " – 16 º 32 ' 44 " W, 211 – 224 m, 1 - XI- 2008: two colonies without gonothecae, 152 – 170 mm high, substrate unknown. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: four colonies with gonothecae, 270 – 366 mm high, substrate unknown. BISSAU- 0810, stn BS 205, 10 º 19 ' 09 " – 10 º 19 ' 47 " N, 16 º 34 ' 20 " – 16 º 35 ' 01 " W, 203 – 204 m, 5 - XI- 2008: one colony without gonothecae, 176 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22EFF76FDC8FC930CE6.taxon	discussion	Remarks. The colony habit, the ramification pattern without secondary hydrocladia, and the presence of a reduced nematotheca behind the adcauline wall of the hydrothecae allowed us to identify undoubtedly our material as P. marocana. Also, the presence of a characteristic mamelon on the cladial apophyses is relevant, as noted by Billard (1930) and Ramil & Vervoort (1992). In some cases, we found quite long cladial internodes with unpaired distal nematothecae (Fig. 11 B), a variation already described by Ramil & Vervoort (1992 a). The genera Polyplumaria and Pseudoplumaria were already included in the family Halopterididae by Calder (1997: 25), an affinity subsequently confirmed by molecular studies (Moura et al. 2018).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22EFF76FDC8FC930CE6.taxon	biology_ecology	Biology. In the northern hemisphere, fertile material has been found in July, October and November (Ansín Agís et al. 2001; Gil & Ramil 2017 a).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22EFF76FDC8FC930CE6.taxon	distribution	Distribution. Pseudoplumaria marocana is an East-Atlantic species recorded from off the Bay of Biscay (Altuna 2012), the Cape San Vicente (Portugal) (Ramil & Vervoort 1992 a, as Plumularia marocana), the Ampère Bank (Ramil et al. 1998), Atlantic side of the Strait of Gibraltar (Medel & Vervoort 1995), Morocco (Billard 1930, as Plumularia marocana; Patriti 1970, as Plumularia marocana; Ramil & Vervoort 1992 a), Mauritania (Ansín Agís et al. 2001; Gil & Ramil 2017 a) and Guinea-Bissau (Gili et al. 1989, as Polyplumularia flabellata). Its bathymetric distribution ranges from 27 to 1378 m (Ramil & Vervoort 1992 a; Ansín Agís et al. 2001). Our material was collected at depths between 79 – 224 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22FFF76F8D7FC2F091F.taxon	description	(Fig. 11 C)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22FFF76F8D7FC2F091F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: one colony without gonothecae, 50 mm high, growing on a worm tube. CCLME- 1110, stn BT 40, 10 º 15 ' 45 " – 10 º 14 ' 39 " N, 16 º 55 ' 17 " – 16 º 54 ' 05 " W, 224 m, 27 - X- 2011: four colonies without gonothecae, 17 – 28 mm high, of which two growing on a prosobranch.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22FFF76F8D7FC2F091F.taxon	discussion	Remarks. Kirchenpaueria pinnata is a well-known species and requires no further comment. Our material represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22FFF76F8D7FC2F091F.taxon	biology_ecology	Biology. Kirchenpauera pinnata has been found growing on algae, bryozoans, polychaete tubes, hydrozoans, sponges, bio-concretions, anthozoans, pebbles and D. pertusum (Peña Cantero & García Carrascosa 2002; Gil et al. 2020). In the northern hemisphere, gonothecae were found throughout the year (Ansín Agís et al. 2001; Peña Cantero & García Carrascosa 2002; Gil et al. 2020). Colonies studied by us were found growing on worm tubes and prosobranchs. Gonothecae were not observed.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBBF22FFF76F8D7FC2F091F.taxon	distribution	Distribution. This species has a mainly East Atlantic distribution, with some isolated and doubtful records from the West Atlantic, Indian and Pacific Oceans (Ansín Agís et al. 2001). Its distribution in West Africa has been recently revised by Gil et al. (2020). Its bathymetric range extends from 0 to 769 m (Ansín Agís et al. 2001; Peña Cantero & García Carrascosa 2002). The colonies studied by us were collected at depths between 186 – 306 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22FFF76FB90FC180C81.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: one colony with male and female gonothecae, 42 mm high, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: two colonies without gonothecae, 30 – 46 mm high, substrate unknown. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: one colony without gonothecae, 51 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22FFF76FB90FC180C81.taxon	discussion	Remarks. This material represents the first record of this species since its description (Gil et al. 2020), and also the first record for Guinea-Bissau. Our colonies showed hydrorhizal adaptations for anchoring onto soft bottoms, a feature also found in the colonies described from Mauritania (Gil et al. 2020).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22FFF76FB90FC180C81.taxon	biology_ecology	Biology. This species has been found growing on D. pertusum and soft bottoms. In the northern hemisphere, gonothecae have been found in November and December (Gil et al. 2020). In our material male and female gonothecae were found in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22FFF76FB90FC180C81.taxon	distribution	Distribution. Nemertesia freiwaldi has been recorded only from Mauritania, between 405 and 642 m depth (Gil et al. 2020). Colonies studied herein were collected at depths between 56 – 306 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22CFF76F883FC930F7F.taxon	description	(Fig. 11 D – E)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22CFF76F883FC930F7F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 132, 11 º 31 ' 33 " N, 17 º 14 ' 07 " W, depth unknown, 23 - X- 2008: four colonies (one with gonothecae), 36 – 54 mm high, of which one growing on Diphasia margareta and another one on a worm tube. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: one colony without gonothecae, substrate unknown. BISSAU- 0810, stn BS 151, 11 º 05 ' 09 " – 11 º 04 ' 15 " N, 17 º 03 ' 15 " – 17 º 03 ' 10 " W, 46 – 47 m, 26 - X- 2008: one colony with gonothecae, 104 mm high, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 43 colonies (five with gonothecae), 26 – 128 mm high, of which two growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 172, 10 º 07 ' 45 " – 10 º 07 ' 02 " N, 16 º 34 ' 11 " – 16 º 33 ' 37 " W, 223 – 224 m, 31 - X- 2008: two colonies without gonothecae, growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 182, 10 º 14 ' 14 " – 10 º 13 ' 22 " N, 16 º 32 ' 49 " – 16 º 32 ' 44 " W, 211 – 224 m, 1 - XI- 2008: one colony without gonothecae, 64 mm high, growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 199, 10 º 16 ' 49 " – 10 º 17 ' 29 " N, 16 º 22 ' 15 " – 16 º 22 ' 49 " W, 65 – 70 m, 4 - XI- 2008: one colony without gonothecae, 42 mm high, substrate unknown. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: one colony with gonothecae, 358 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22CFF76F883FC930F7F.taxon	discussion	Remarks. For many years, this species has been considered as a junior synonym of Nemertesia antennina (Linnaeus, 1758) but, after reviewing a large number of specimens from Northwest Africa, Gil et al. (2020) emphasized the distinguishing characters allowing their specific separation. The material studied here agrees with that described by Gil et al. (2020) and, based on their records, we have extended its geographical distribution southwards. In addition, gonothecae were found for the first time in October. Most of the colonies of N. irregualis studied herein were used as substrates by other hydroids. In some colonies from station BS 152, we observed a phenomenon of auto-epizoism.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22CFF76F883FC930F7F.taxon	biology_ecology	Biology. Some colonies of N. irregularis have been found growing on D. pertusum (Gil et al. 2020). In the northern hemisphere, fertile material has been found in May, June (Ramil & Vervoort 1992 a; Ansín Agís et al. 2001, both as N. antennina) November and December (Gil et al. 2020). In our material, some colonies were found growing on D. margareta, L. myriophyllum and a worm tube. Gonothecae were found in October and November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBAF22CFF76F883FC930F7F.taxon	distribution	Distribution. Nemertesia irregularis is an East Atlantic species (Gil et al. 2020) with a wide bathymetric distribution, ranging from 12 to 2450 m depths (Ansín Agís et al. 2001). In West Africa, it was recorded from Morocco to the Cape Verde Islands (Gil et al. 2020). Our material was collected at depths between 46 – 306 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB9F22DFF76FA21FC910AB7.taxon	materials_examined	Material examined. CCLME- 1110, stn BT 60, 12 º 03 ' 04 " – 12 º 01 ' 38 " N, 17 º 23 ' 45 " – 17 º 23 ' 34 " W, 478 – 486 m, 30 - X- 2011: one colony without gonothecae, 77 mm high, substrate unknown.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB9F22DFF76FA21FC910AB7.taxon	discussion	Remarks. Our material conforms to that studied by Gil et al. (2020) from the Mauritanian coral mounds. No further discussion is required.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB9F22DFF76FA21FC910AB7.taxon	biology_ecology	Biology. This species usually provides a substrate for other hydroids, and is common in mixed sand and muddy bottoms. Conversely, it has also been found growing on polychaete tubes (Medel & Vervoort 1995; Peña Cantero & García Carrascosa 2002). In the northern hemisphere, gonothecae have been found between February – May, July and August (Ansín Agís et al. 2001; Peña Cantero & García Carrascosa 2002; Gil & Ramil 2017 a).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB9F22DFF76FA21FC910AB7.taxon	distribution	Distribution. Nemertesia perrieri has been recorded from NW France to Guinea-Bissau, including the Mediterranean Sea (Gili et al. 1989; Gil et al. 2020). Its distribution in NW Africa has recently been revised by Gil et al. (2020). Its bathymetric distribution ranges from 5 to 1837 m depth (Ansín Agís et al. 2001; Peña Cantero & García Carrascosa 2002; Gil & Ramil 2017 a). Our colony was collected at depths between 478 – 486 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB8F22DFF76FEE9FC930D76.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: two colonies (one with gonothecae), 80 – 98 mm high, of which one growing on a worm tube. BISSAU- 0810, stn BS 151, 11 º 05 ' 09 " – 11 º 04 ' 15 " N, 17 º 03 ' 15 " – 17 º 03 ' 10 " W, 46 – 47 m, 26 - X- 2008: one colony without gonothecae, 105 mm high, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: five colonies without gonothecae, 63 – 175 mm high, substrate unknown. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: six colonies without gonothecae, 90 – 320 mm high, of which one growing on a worm tube. BISSAU- 0810, stn BS 174, 10 º 01 ' 42 " – 10 º 02 ' 16 " N, 17 º 00 ' 52 " – 17 º 01 ' 35 " W, 419 m, 31 - X- 2008: one colony without gonothecae, 235 mm high, growing on a worm tube. BISSAU- 0810, stn BS 195, 10 º 22 ' 44 " – 10 º 23 ' 22 " N, 16 º 15 ' 37 " – 16 º 16 ' 18 " W, 29 m, 3 - XI- 2008: one colony without gonothecae, 49 mm high, substrate unknown. BISSAU- 0810, stn BS 199, 10 º 16 ' 49 " – 10 º 17 ' 29 " N, 16 º 22 ' 15 " – 16 º 22 ' 49 " W, 65 – 70 m, 4 - XI- 2008: 13 colonies (some with gonothecae), 110 – 206 mm high, substrate unknown. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: two colonies without gonothecae, 74 – 119 mm high, substrate unknown. BISSAU- 0810, stn BS 216, 10 º 30 ' 53 " – 10 º 31 ' 39 " N, 16 º 31 ' 33 " – 16 º 32 ' 02 " W, 56 – 58 m, 7 - XI- 2008: four colonies without gonothecae, 90 – 170 mm high, substrate unknown. CCLME- 1110, stn BT 40, 10 º 15 ' 45 " – 10 º 14 ' 39 " N, 16 º 55 ' 17 " – 16 º 54 ' 05 " W, 224 m, 27 - X- 2011: one colony without gonothecae, 15 mm high, substrate unknown. CCLME- 1110, stn BT 49, 10 º 57 ' 13 " – 10 º 58 ' 26 " N, 16 º 59 ' 29 " – 17 º 00 ' 29 " W, 62 m, 29 - X- 2011: one colony without gonothecae, 14 mm high, growing on a polychaete tube.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB8F22DFF76FEE9FC930D76.taxon	discussion	Remarks. Nemertesia ramosa is a well-known species in the East Atlantic and does not require further comments.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB8F22DFF76FEE9FC930D76.taxon	biology_ecology	Biology. Nemertesia ramosa has been mainly collected from non-living hard substrates, but also as an epizoite of other hydroids, anthozoans, bivalves, decapod crustaceans, as well as growing directly on muddy bottoms (Peña Cantero & García Carrascosa 2002; Gravili et al. 2015). In the northern hemisphere, fertile material has been collected from January to October and December (Ansín Agís et al. 2001; Peña Cantero & García Carrascosa 2002), while in the southern hemisphere, gonothecae were observed in September (Millard, 1957). In our material, some colonies were found growing on worm tubes. Gonothecae were observed in October and November.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB8F22DFF76FEE9FC930D76.taxon	distribution	Distribution. East Atlantic species distributed from Iceland and Norway to South Africa (Calder 2012). In West Africa, it has been recorded from Morocco, Western Sahara, Mauritania, Gambia, the Cape Verde Archipelago, Guinea-Bissau, the Republic of Guinea, the Ivory Coast, Ghana and Namibia (Ansín Agís et al. 2001). Its bathymetric distribution ranges from 3 to 1425 m (Ansín Agís et al. 2001; Peña Cantero & García Carrascosa 2002). Our material was collected at depths between 29 – 308 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22AFF76FF35FDED0FB7.taxon	description	(Fig. 11 F)	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22AFF76FF35FDED0FB7.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 133, 11 º 29 ' 17 " – 11 º 28 ' 26 " N, 17 º 15 ' 14 " – 17 º 15 ' 14 " W, 733 – 737 m, 23 - X- 2008: seven colonies without gonothecae, 40 – 70 mm high, of which five growing on worm tubes. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: nine colonies without gonothecae, 13 – 122 mm high, of which one growing on Halecium halecinum. BISSAU- 0810, stn BS 149, 11 º 06 ' 46 " – 11 º 07 ' 39 " N, 17 º 06 ' 23 " – 17 º 06 ' 40 " W, 71 m, 26 - X- 2008: one colony without gonothecae, 138 mm high, substrate unknown. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 18 colonies without gonothecae, 30 – 175 mm high, of which one growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 157, 10 º 19 ' 36 " – 10 º 18 ' 44 " N, 17 º 10 ' 29 " – 17 º 10 ' 12 " W, 304 – 308 m, 28 - X- 2008: three colonies without gonothecae, 29 – 176 mm high, substrate unknown. BISSAU- 0810, stn BS 173, 10 º 04 ' 52 " – 10 º 04 ' 17 " N, 16 º 34 ' 12 " – 16 º 33 ' 30 " W, 277 – 278 m, 31 - X- 2008: three colonies without gonothecae, 47 – 163 mm high, substrate unknown. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: two colonies without gonothecae, 79 mm high, of which one growing on Diphasia digitalis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22AFF76FF35FDED0FB7.taxon	discussion	Remarks. Nemertesia ventriculiformis is similar to N. norvegica (G. O. Sars, 1874) and N. falcicula (Ramil & Vervoort, 1992) with respect to the trophosome. The differences between all three species have been highlighted by Ansín Agís et al. (2001), and are mainly based on gonothecal features, with also some trophosomal differences. The presence of two lateral nematothecae, the shape and size of the hydrothecae and the presence of numerous, characteristic perisarcal ridges in the hydrocladial internodes allowed us to identify our material as N. ventriculiformis. Our material represents the first record of this species for Guinea-Bissau.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22AFF76FF35FDED0FB7.taxon	biology_ecology	Biology. In the northern hemisphere, colonies with gonothecae have been found in June, July, September, November and December (Ansín Agís et al. 2001; Gil & Ramil 2017 a). In our material, some colonies were found growing on worm tubes and other hydroids, such as H. halecinum, L. myriophyllum and D. digitalis.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22AFF76FF35FDED0FB7.taxon	distribution	Distribution. Nemertesia ventriculiformis is an East Atlantic-Mediterranean species known from the Glénan Archipelago (France) to Senegal including the Mediterranean Sea, with a bathymetric range extending from 10 to 930 m (Ansín Agís et al. 2001). In West Africa, it has been collected from Morocco (Ramil & Vervoort 1992 a), Mauritania (Gil & Ramil 2017 a) and the Cape Verde Archipelago (Ansín Agís et al. 2001). Our material was collected at depths between 24 – 737 m. Genus Plumularia Lamarck, 1816	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22BFF76F985FC0E0883.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 147, 11 º 08 ' 35 " – 11 º 08 ' 27 " N, 17 º 11 ' 31 " – 17 º 10 ' 37 " W, 186 – 306 m, 26 - X- 2008: two colonies without gonothecae, growing on Diphasia margareta. BISSAU- 0810, stn BS 152, 10 º 31 ' 12 " – 10 º 30 ' 19 " N, 17 º 12 ' 34 " – 17 º 12 ' 32 " W, 300 – 305 m, 27 - X- 2008: 22 colonies (four with gonothecae), all growing on Lytocarpia myriophyllum. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: three colonies without gonothecae, substrate unknown. BISSAU- 0810, stn BS 192, 10 º 19 ' 30 " – 10 º 20 ' 15 " N, 16 º 10 ' 27 " – 16 º 10 ' 59 " W, 24 m, 3 - XI- 2008: one colony without gonothecae, 12 mm high, substrate unknown. BISSAU- 0810, stn BS 200, 10 º 18 ' 55 " N, 16 º 25 ' 07 " W, 79 m, 4 - XI- 2008: four colonies without gonothecae, growing on Pseudoplumaria marocana.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22BFF76F985FC0E0883.taxon	discussion	Remarks. Plumularia setacea is a well-known species and requires no further comment.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22BFF76F985FC0E0883.taxon	biology_ecology	Biology. This species has been found growing on algae, bio-concretions, mollusk shells, bryozoans, sponges, cirripeds, anthozoans and other hydroids (Peña Cantero & García Carrascosa 2002; Gil & Ramil 2021 a). Gonothecae have been found throughout the year in both hemispheres (Gili et al. 1989; Ansín Agís et al. 2001; Genzano & Zamponi 2002). Our colonies were found growing on the hydroids D. margareta, L. myriophyllum and P. marocana. Gonothecae were observed in October.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBFF22BFF76F985FC0E0883.taxon	distribution	Distribution. Plumularia setacea is a circumglobal species (Ansín Agís et al. 2001; Gil et al. 2020). In West Africa, it has been recorded from Morocco to Namibia (Gil et al. 2020), including the Vema Seamount (Millard 1966 b; Gil & Ramil 2021 b). Its bathymetric distribution ranges from 0 to 1513 m (Ansín Agís et al. 2001; Gil & Ramil 2017 a). The material studied by us was collected at depths between 24 – 306 m.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBEF228FF76FC0CFE9F0B9F.taxon	materials_examined	Material examined. BISSAU- 0810, stn BS 191, 10 º 18 ' 25 " – 10 º 19 ' 20 " N, 16 º 08 ' 47 " – 16 º 08 ' 47 " W, 24 – 25 m, 3 - XI- 2008: one colony without gonothecae, growing on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBEF228FF76FC0CFE9F0B9F.taxon	discussion	Remarks. For many years, some authors have noted the need to evaluate the appropriateness of the inclusion of the genus Hydrodendron Hincks, 1874 within the family Haleciidae (Watson 1969; Cornelius 1975), due to the presence of nematophores. Furthermore, during the last decades, several molecular studies have shown a clear divergence between Hydrodendron and Halecium species (Maronna et al. 2016). Moreover, the peculiar morphological characters of H. mirabile are shared with genera of the superfamily Plumularioidea (Choong et al. 2018). Consequently, several authors proposed to include this species in the family Phylactothecidae within the superfamily Plumularioidea to accommodate all the species belonging to the genus Hydrodendron (see Choong et al. 2018), an opinion followed here.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBEF228FF76FC0CFE9F0B9F.taxon	biology_ecology	Biology. This species has been often collected growing on algae, but also on rocks, seagrasses, hydroids and other invertebrates (Peña Cantero & García Carrascosa 2002). In the northern hemisphere, fertile material has been collected in July in the Mediterranean (Motz-Kossowska 1911). The colony studied by us was found growing on a bryozoan.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFBEF228FF76FC0CFE9F0B9F.taxon	distribution	Distribution. Hydrodendron mirabile is an Indo-West Pacific species restricted to tropical and temperate waters (Peña Cantero & García Carrascosa 2002). In West Africa, it has been recorded from the Cape Verde Archipelago (Ritchie 1907, as O. caciniformis; Rees & Thursfield 1965, as H. caciniformis), Guinea-Bissau (Vervoort 1959, as O. caciniformis; Gili et al. 1989) and Congo (Bouillon et al. 1995). Its bathymetric range extends from 0 (Millard 1975; Ramil & Iglesias 1988, as O. mirabilis) to 65 m (Vervoort 1959, as O. caciniformis). Our material was collected at depths between 24 – 25 m. CHECKLIST OF THE HYDROIDS REPORTED FROM GUINEA-BISSAU In the checklist provided below, we have also included the taxa identified by Moura et al. (2024). Nevertheless, we believe that the hydroid species cited in this study should be taken with caution, due to all species identifications were based only on morphospecies separation and molecular analyses, as the proper authors recognize. Of the 15 hydrozoan species mentioned there, 11 are identified as cf. or aff. An integrative taxonomic study with formal taxonomic descriptions, drawings and biometric date of the sequenced material is required to confirm their identifications or to describe putative new species. Records of species dealt with by Moura et al. (2024) are marked with an asterisk.	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
846787B2FFB0F222FF76FAFCFCE109CF.taxon	description	Macrorhynchia cf. philippina Kirchenpauer, 1872 * — (11.049997 N, 15.607268 W), 1 – 3 m; (11.52462 N, 16.22524 W), 5 – 8 m; (11.52812 N, 16.14595 W), 5 m; (11.050670 N, 15.649258 W), 1 – 3 m (Moura et al. 2024).	en	Gil, Marta, Ramil, Fran (2025): Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau. Zootaxa 5577 (1): 1-89, DOI: 10.11646/zootaxa.5577.1.1, URL: https://doi.org/10.11646/zootaxa.5577.1.1
