taxonID	type	description	language	source
038987ACF555FFFCB188FAAAAE80FCF6.taxon	description	The molecular phylogenies presented here also recover a well-supported clade containing individual specimens identified as Aplysia parvula and A. punctate, and therefore corroborates the results of Medina et al. (2001) and the validity of the subgenus Pruvotaplysia. However, because of a much larger sample size, our phylogenetic analysis recovers additional subclades in Pruvotaplysia. Below we describe these subclades and assign them names (and synonyms) based on a review of the literature and morphological comparisons. Because some of the newly recognized species are cryptic or pseudocryptic, we will arrange such species into species complexes, meaning groups of closely related, but genetically distinct, species that are indistinguishable morphologically. SPECIES COMPLEX 1 THE APLYSIA PARVULA – ATROMARGINATA SPECIES COMPLEX (FIGS 6 – 9) Diagnosis External anatomy: Animal robust, elongate, wider in visceral region, narrowing gradually toward head and tail (Fig. 6); visceral hump large, oval, not clearly differentiated from rest of body, occupying ~ 1 / 4 – 1 / 3 of body length; mantle foramen relatively small, circular, elevated (resembling a volcano), located near centre of visceral hump; parapodia narrow, fused posteriorly, typically joined anteriorly, forming a single, narrow, conspicuous fold mid-length; rhinophores and oral tentacles elongate, enrolled, with several projections in oral tentacles; siphon wide, elongate, clearly protruding above parapodia. Colour cream to brownish red, completely covered with white pigment, often aggregated in dense concentrations; parapodia edged in white, typically with submarginal bluish band (sometime absent), not interrupted with white spots; rhinophores and oral tentacles with dark tips; mantle foramen with conspicuous dark inner edge and series of radial white lines (Fig. 6). Internal anatomy: Shell elongated, narrow, widest near posterior end; posterior left side regularly curved, posterior right side conspicuously concave adjacent to protoconch (Fig. 7); rachidian tooth with robust, triangular central cusp bearing multiple sharp denticles, 2 – 3 lateral cusps on each side of central cusp, lacking denticles (Figs. 8 A, 8 D, 8 G); lateral teeth with haplotypes as indicated in scale. Dashed lines separate haplotypes belonging to different species recognized in this study. A, species complex 1: Aplysia parvula – atromarginata species complex. B, species complex 2. C, A. japonica. D, species complex 3: A. elongata – nigrocincta species complex. E, A. punctata. central cusp denticulated on both sides, larger tooth or secondary cusp near base; up to seven simple outer teeth (Figs. 8 B, 8 E, 8 H); jaw with cylindrical, elongated elements with 2 – 4 cusps at tips (Figs. 8 C, 8 F, 8 I). Penis elongate, narrow, simple, with two retractor muscles, papillae absent (Fig. 9). Remarks	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF549FFFDB043FC55AAB7FDA4.taxon	description	(FIGS 4 A – B, 6 A – B, 7 A, 8 D – I, 9 B)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF549FFFDB043FC55AAB7FDA4.taxon	materials_examined	Additional material examined: St. John, US Virgin Islands, 15 April 2006, one specimen 11 mm preserved length, leg. A. Valdés (LACM 3642, isolate HG 11). Guana Island, British Virgin Islands, 4 - m depth, 5 July 2000, one specimen 15 mm preserved length, leg. T. Zimmerman & G. Hendler (LACM FP 2.2007 - 3). Description: Morphological characteristics as in Aplysia parvula-atromarginata species complex description. Radular formula? × 6.9.1.9. 6 in an 11 mm preserved length specimen from the US Virgin Islands (CPIC 00140, isolate HG 11) and 29 × 6.10.1.10. 6 in a specimen from the British Virgin Islands (LACM FP 2.2007 - 3). Range: North-eastern Atlantic, from the Virgin Islands to northern Brazil. Remarks In the present study we examined specimens from the Virgin Islands, Honduras and northern Brazil, which form a well-supported clade and are morphologically and genetically distinct from most other animals examined from the western Atlantic and the Caribbean region (Fig. 2 A). This clade is nested in a larger clade (species complex 1) also including animals from the western Pacific and St. Helena, each forming a well-supported clade. Animals in species complex 1 are morphologically distinct from other A. parvula s. l. species complexes (Table 3). Although the ABGD analysis did not recover the three clades in species complex 1 as distinct species, haplotype network analyses revealed that they do not share mtDNA haplotypes and their geographic ranges do not overlap (Fig. 3 A). Because of this, the three clades of species complex 1 are here regarded as distinct species. A review of the literature was conducted to determine the valid name for the north-western Atlantic species, including animals from the Virgin Islands, Honduras and Northern Brazil. Mörch (1863) introduced the name Aplysia parvula (assigned to Guilding), based on specimens collected from the US Virgin Islands. The shell was briefly described as solid, semitranslucent, white, convex, suboval, narrow, with a bent spire. Mörch (1863) also described two specimens: (1) a ‘ flaccid’ specimen with a soft, narrow, fusiform body, having short parapodia fused together posteriorly and sub-lateral eyes, posterior to the base of the tentacles (= rhinophores), which are narrow and pointed; (2) a contracted specimen, with hard, rugose and wrinkled skin, shell foramen large and oval, surrounded by a black line as the margin of the parapodia. The characteristics of all of these animals match those of the specimens here examined from the north-western Atlantic included in this section and characterized by having narrow and elongate bodies with the mantle foramen centred and surrounded by a conspicuous black line. We are, therefore, confident that the name A. parvula should be applied to this species. The original description of Aplysia parvula by Mörch (1863) was based on specimens collected in St. Thomas by Riise and Hornbeck and St. Vincent by Guilding. None of these specimens were found in the NHMD collections (K. Jensen, pers. comm.) and are probably lost. But Mörch (1863) also commented: ‘ J’ai vu, en 1854, la coquille de cette espèce sous le nom indiqué, mais non publié à ma connaissance, dans la collection du Musée Britannique. ’ This shell is, therefore, another syntype for this species, but is no longer at the NHMUK (A. Salvador, pers. comm.). However, a shell collected by Ørsted in 1849 in ‘ Vestindien’ (= West Indies) with the notation ‘ Brit mus ’ written on the label and matching the size of the material described by Mörch, was located at the NHMD collections (K. Jensen, pers. comm.). This shell (NHMD 288589) is possibly a third syntype of A. parvula. The characteristics of this shell, which is elongate, narrow, widest near posterior end, with the posterior left side regularly curved, and the posterior right side conspicuously concave adjacent to protoconch, matches those of shells here regarded as A. parvula, providing additional confidence in the identification of these animals. Engel (1936) divided Aplysia parvula into six different subspecies and restricted the use of the name A. parvula parvula to Atlantic animals, including records from St. Vincent identified by G. B. Sowerby II (1869) as A. rosea and from Key West, Florida by Eliot (1899) under the name A. parva (error for A. parvula).	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF548FFFDB2C3FD83ABCDFBD7.taxon	description	(FIGS 6 C, 7 B, 8 A – C, 9 A)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF548FFFDB2C3FD83ABCDFBD7.taxon	materials_examined	Additional material examined: Madang, Papua New Guinea, 6 December 2012, one specimen 8 mm preserved length, leg. J. Goodheart (CPIC 00821, isolate HG 25). Description: Morphological characteristics as in the Aplysia parvula-atromarginata species complex description. Radular formula 30 × 5.7.1.7. 5 in an 8 - mm long preserved specimen from Madang, Papua New Guinea (CPIC 00821, isolate HG 25).	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF54EFFF8B0D9FBE1AE1BF8D9.taxon	description	(FIG. 6 D – F) Description: External morphological characteristics as in Aplysia parvula – atromarginata species complex description. Internal anatomy not examined. Range: Appears to be endemic to St. Helena, south Atlantic Ocean. Remarks: Specimens from St. Helena sequenced for this study were found to form a monophyletic group and were recovered as a distinct species. However, due to the lack of specimens for morphological examination, this species is not formally named here. SPECIES COMPLEX 2 (FIGS 10 – 13) Diagnosis External anatomy: Animal slender, elongate, much wider in visceral region, narrowing abruptly towards head and tail (Fig. 10); visceral hump small, rounded, well differentiated from rest of body, occupying less than 1 / 5 of body length; mantle foramen large, oval, on posterior left side of visceral hump, not elevated; parapodia broad, fused posteriorly, typically joined high up, forming several shallow folds; rhinophores and oral tentacles elongate, enrolled, with conspicuous flat posterior projection in oral tentacles; siphon narrow, elongate, typically protruding above parapodia. Colour yellowish to brownish red, completely covered with white dots, often aggregated in dense concentrations; parapodia edged in white, with submarginal black band, interrupted with white spots; rhinophores and oral tentacles with conspicuously dark tips; mantle foramen with dark inner edge interrupted with white patches (Fig. 10). Internal anatomy: Shell elongated, narrow, widest near posterior end; posterior left side regularly curved, posterior right side slightly concave adjacent to protoconch (Fig. 11); rachidian tooth with robust, broad, triangular central cusp bearing multiple sharp denticles, 2 – 4 lateral cusps on each side of central cusp, lacking denticles (Figs. 12 A, 12 D, 12 G); each lateral tooth with central cusp denticulated on both sides, larger tooth or secondary cusp near base; up to four simple outer teeth (Figs. 12 B, 12 E, 12 H); jaw with cylindrical, elongated elements with no cusps at tips (Figs. 12 G, 12 F, 12 I). Penis elongate with two retractor muscles, and two papillae on the tip (Fig. 13). Remarks Species in this complex are clearly different morphologically from other species of Aplysia parvula s. l. The most obvious external differences are the elongate, slender body, with a small, rounded visceral hump that is well-differentiated from the rest of the body, the presence of a dark parapodial margin interrupted with white spots and a large mantle foramen on the posterior left side of the visceral hump. Internally, species in this complex are characterized by having a penis with two papillae at the tip. Molecular data recovered two well-supported clades in this species complex: one including specimens collected in the Atlantic Ocean and adjacent Indian Ocean (Madagascar and Mozambique) and the other including specimens from the tropical western Pacific Ocean (Okinawa and Vanuatu). We have no observed consistent morphological differences between these two clades.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF54DFFF6B2EEF9C0AA87F8F2.taxon	description	(FIGS 10 A – E, 11 A – B, 12 A – C, 12 G – I, 13 A – C) Type material: Holotype: Stocking Is., Bahamas, 18 January 2007, specimen 6 mm preserved length, leg. A. DuPont LACM 3643 (ex. CPIC 00040, isolate HG 22). urn: lsid: zoobank. org: act: 673 B 6957 - 9 CDF- 470 E- 89 BB-EDBD 58 C 45 ECF Additional material examined: West Palm Beach, Florida, USA, 14 April 2013, onespecimen 7 mmpreserved length, leg. A. Dimitris (CPIC 01376, isolate HG 30); 14 April 2013, one specimen 9 mm preserved length, leg. A. Dimitris (CPIC 01375, isolate HG 29). Stocking Is., Exumas, Bahamas, 19 January 2007, one specimen 13 mm preserved length, leg. A. DuPont (CPIC 00041, isolate HG 10); 11 February 2010, one specimen 7 mm preserved length, leg. A. DuPont (CPIC 00229, isolate HG 4); 8 January 2010, one specimen 3 mm preserved length, leg. A. DuPont (CPIC 00226, isolate HG 3); 2 - m depth, 19 January 2007, one specimen, leg. A. DuPont (CASIZ 175666). South Madagascar, 1 - m depth, 13 May 2010, one specimen, leg. Atimo Vatae Expedition (CASIZ 194076); 7 - m depth, 16 May 2010, eight specimens, leg. Atimo Vatae Expedition (CASIZ 194433). Description: Morphological characteristics as in species complex 2 description. Radular formula 28 × 3.7.1.7. 3 in a 7 - mm preserved length specimen from the Bahamas (CPIC 00229, isolate H 4) and 33 × 4.9.1.9. 4 in a 7 - mm preserved length specimen from Florida (CPIC 01376, isolate HG 30). Etymology: Named after Hessam Ghanimi in appreciation for his help with this manuscript, including primer design and sequencing a number of specimens. Range: Tropical and subtropical Atlantic and western Indian Ocean. Remarks Aplysia ghanimii is genetically distinct from other, here examined, species of A. parvula s. l. The specimens included in this species form a well-supported clade (Fig. 2 A) and the ABGD analysis recovers it as a distinct species (Table 2). Morphologically, A. ghanimii is similar to other animals included in species complex 2 in being characterized by having slender and elongate bodies, much wider in visceral region and short penises with two papillae (Table 3). These characteristics make animals in species complex 2 easily identifiable and distinguishable from other species previously assigned to A. parvula. A review of the literature reveals that no available names can be applied to this species with certainty, thus we here propose the new name A. ghanimii for it. Animals from Bermuda illustrated by Jensen & Clark (1986: pl. 12, fig. 6) are externally similar to specimens from the Bahamas here examined and probably belong to Aplysia ghanimii, but this needs to be confirmed with molecular data.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF542FFF7B0D9FC09AEB9FA93.taxon	description	(FIGS 10 F – G, 11 C, 12 D – F, 13 D) Material examined: Okinawa, Japan, 3 - m depth, 21 May 1989, one specimen 30 - mm long, leg. R. F. Bolland (CASIZ 070096); intertidal, 15 Machr 1987, one specimen 30 - mm long, leg. R. F. Bolland (CASIZ 070053, HG 100). Description: Morphological characteristics as in the descrition of species complex 2. Radular formula n × 4.8.1.8. 4 in a 30 mm long specimen from Okinawa, Japan (CASIZ 070096).	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF540FFF3B045FA75AE30F9A5.taxon	description	(FIGS 4 E – H, 14 E – G, 15 A, 16 D – F, 17 A)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF540FFF3B045FA75AE30F9A5.taxon	materials_examined	Additional material examined: Napili Bay, Maui, Hawaiian Islands, 13 June 2011, one specimen 3.5 mm preserved length, leg. D. Hanson, J. Alexander, J. Goodheart, A. Valdés (CPIC 00300, isolate HG 5); 15 June 2011, one specimen 5 mm preserved length, leg. D. Hanson, J. Alexander, J. Goodheart, A. Valdés (CPIC 00325, isolate HG 18). Maliko Bay, Maui, Hawaiian Islands, 18 June 2011, one specimen 3.5 mm preserved length, leg. D. Hanson, J. Alexander, J. Goodheart, A. Valdés (CPIC 00363, isolate HG 6); one specimen 1.5 mm preserved length, leg. D. Hanson, J. Alexander, J. Goodheart, A. Valdés (CPIC 00368, isolate HG 21). Maui, Hawaiian Islands, 16 June 2011, one specimen 8 mm preserved length, leg. D. Hanson, J. Alexander, J. Goodheart, A. Valdés (CPIC 00333, isolate HG 9). Description: Morphological characteristics as in description of species complex 3. Radular formula 22 × 3.6.1.6. 3 in an 8 - mm long preserved specimen from Maui, Hawaiian Islands (CPIC 00333, isolate HG 9). Range: Appears to be endemic to the Hawaiian Islands. Remarks In this study, we found only one species of Aplysia parvula s. l. present in the Hawaiian Islands, including six sequenced specimens. This species appears to be endemic to this archipelago and no other species has been found there. A search of the literature reveals that only one name was introduced for A. parvula s. l. based on material collected from the Hawaiian Islands. Pease (1860) described Aplysia elongata based on an undetermined number of specimens collected in the Hawaiian Islands. The specimens were described as brown, darker on top of the head and neck, with an oblong body, an elevated dorsum and strongly dilated and undulated parapodia, free nearly the entire length. No illustrations were provided. We have access to photographs of several syntypes of A. elongata (Fig. 4 E – H) (dry shells), which are consistent morphologically with those of other specimens of A. parvula s. l. Engel (1936) regarded A. elongata as a valid subspecies of A. parvula, restricted to the Pacific Islands and Australia. Engel (1936) included in this subspecies the original description by Pease (1860) from the Hawaiian Islands and records from Samoa by Eliot (1899) as A. nigrocincta, from the Society Islands by Pease (1868) as Siphonota punctata and from Norfolk Island and Sydney, Australia by Sowerby II (1869) and Allan (1932) as A. norfolkensis. Eales (1960) considered A. elongata as a probable synonym of A. parvula.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF546FFCEB069F980AEB5F9BA.taxon	description	(FIGS 14 D, 15 A – B, 16 G – I, 17 B – C) Holotype: Punta Belches, Baja California, Mexico, 1 September 2015, 10 - mm long preserved specimen, leg. C. Hoover (LACM 3644, isolate HG 97).	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF546FFCEB069F980AEB5F9BA.taxon	materials_examined	Additional material examined: Punta Belches, Baja California, Mexico, 1 September 2015, one specimen 9 mm preserved length, leg. C. Hoover (CPIC 01851, isolate HG 94); 1 September 2015, one specimen 6 mm preserved length, leg. C. Hoover (CPIC 01848, isolate HG 98); one specimen 9 mm preserved length, leg. C. Hoover (CPIC 01845, HG 95). Baja California, Mexico, 10 - m depth, 30 June 1987, three specimens, leg. S. Millen (CASIZ 071868). Tenacatita, Jalisco, Mexico, 16 January 1976, two specimens 11 mm preserved length, leg. Forrest & R. Poorman (LACM 117921). Isla Coiba, Panama, 10 – 21 - m depth, 8 May 2003, one specimen 4 mm preserved length, leg. A. Hermosillo (LACM 153315). Bahia Honda, La Guajira, Colombia, 16 – 18 - m depth, 8 April 1939, one specimen 19 mm preserved length, leg. R / VVelero III (LACM 1939 - 188.4). Black Beach, Floreana Island, Galapagos, Ecuador, 6 m depth, 17 January 1934, one 1 specimen 19 mm preserved length (LACM AHF 161 - 34); 5 – 10 - m depth, 23 January 1972, two specimens 11 – 14 mm preserved length, leg. S. Earle (LACM 72 – 190). Tumbes, Peru, 3 December 2006, three specimens, leg. M. Schrödl & Y. Hooker (ZSM Mol 20090834). Description: Morphological characteristics as in the description of species complex 3. Radular formula 27 × 3.7.1.7. 3 in a 9 - mm long preserved specimen from Baja California, Mexico (CPIC 01851, isolate HG 94) and 25 × 3.8.1.8. 3 in a 9 - mm long preserved specimen from Baja California, Mexico (CPIC 01845, HG 95). Etymology: Named after Craig Hoover, enthusiast of sea slug taxonomy and ecology, who collected the holotype of this new species. Range: Eastern Pacific Ocean, mainly along the Panamic Biogeographic Region. Reported from San Clemente Island, California (Behrens & Hermosillo, 2005) to Peru (Uribe et al., 2013) as Aplysia parvula. Remarks The results of this study confirm that the eastern Pacific specimens sequenced are genetically distinct from other specimens collected in other regions of the Pacific Ocean. Based on these results, and the species delimitation analyses, we conclude that these specimens constitute a distinct species. However, we have been unable to find an available or valid name for the eastern Pacific species here recognized, thus we introduce the new name Aplysia hooveri for these specimens. MacFarland (1924) reported Aplysia parvula for the first time for the eastern Pacific, based on three specimens collected in Isla San Marcos, Baja California, Mexico. Engel (1936) divided A. parvula into several subspecies with different geographic ranges and introduced the name Aplysia parvula subsp. californica Engel, 1936 for the specimens reported by MacFarland (1924). Engel (1936) stated the type locality of the new subspecies as California, but this is probably an error for Baja California, as the name was based on MacFarland’s (1924) specimens. However, Engel (1936) did not include a description or a statement of differentiation, thus the name Aplysia parvula californica Engel, 1936 does not meet the criteria of availability (ICZN 1999: Article 13.1). Aplysia juanina is another species from the eastern Pacific Ocean that was regarded as a synonym of Aplysia parvula, but this species is genetically distinct from Aplysia hooveri and other closely related species previously included in Aplysia parvula (see remarks under Aplysia juanina).	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF57BFFCDB19DF998AEF8F960.taxon	description	(FIGS 4 K – M, 14 A – C, 14 H, 15 C, 16 A – C, 17 D)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF57BFFCDB19DF998AEF8F960.taxon	materials_examined	Additional material examined: Savai’i Island, Samoa, leg. M. Schrödl (ZSM Mol 20060223). Mindoro, Philippines, 28 April 2015, one specimen, leg. P. J Aristorenas (CASIZ 208581, isolate HG 105). Madang, Papua New Guinea, 19 November 2012, one specimen, leg. V. Knutson (CASIZ 191335, isolate HG 102); 9 November 2012, one specimen, leg. V. Knutson (CASIZ 191092, isolate HG 103). Mozambique, one specimen 9 mm preserved length, leg. M. Pola (CPIC 01386, isolate HG 85). Description: Morphological characteristics as in the description of species complex 3. Radular formula 22 × 3.6.1.6. 3 in a 9 mm preserved length specimen from Mozambique (CPIC 01386, isolate HG 85), n × 2.6.1.6. 2 in a 15 mm preserved length specimen from the Philippines (CASIZ 208581, isolate HG 105) and n × 3.7.1.7. 3 in a 20 mm preserved length specimen from Papua New Guinea (CASIZ 191335, isolate HG 102). Range: The range of Aplysia nigrocincta has been confirmed to include the Indian and eestern Pacific Oceans, from East Africa (Mozambique) to Mauritius, the Philippines, Papua New Guinea, Indonesia and Vanuatu. Remarks Several specimens from the tropical Indo-Pacific of A. parvula s. l. sequenced here constitute a distinct species, as confirmed by the ABGD analysis. These specimens are morphologically and genetically members of species complex 3, but are distinct from other species in this complex from the eastern Pacific and the Hawaiian Islands. A review of the literature reveals that the name A. nigrocincta von Martens, 1880 most likely represents this species. Von Martens (1880) introduced the name A. nigrocincta based on a 17 - mm long preserved specimen collected from Mauritius and described it as: ‘ Wide, smooth, light brown, the free edges of the foot flaps, the edge of the sole of the foot and the edge of the rather large hole in the coat (shields) black, mostly continuous, sometimes slightly stained. Shell strongly domed, comparatively large, vivacious amber-yellow, reddish translucent by the shield, spoon-shaped, with a shallow neck and strongly inflected point, occupying more than half the length of the contracted animal. ’ This description matches the characteristics of animals in species complex 3, including the presence of a large mantle foramen edged in black and a very large visceral hump, occupying a large portion of the animal. We also examined the type material of A. nigrocincta, which consists of two syntypes remaining, a dry shell specimen and a wet specimen with a shell and some soft parts remaining (ZMB Moll 32165, ZMB Moll 51472) (Fig. 4 K – M). These specimens are consistent with the animals here examined and assigned to this species, and there are no major differences between them. Based on other material of A. parvula s. l. here examined from the Indo-Pacific, the descriptions associated with the name A. nigrocincta most closely matches the specimens included in this section and, therefore, we are confidently using this name for this species. Engel (1936) considered A. nigrocincta as a valid species endemic to East Africa, including specimens identified by Burne (1906) as A. nigrocincta and A. elongata. In this study we found the range of A. nigrocincta to extend from the western Indian Ocean to the western Pacific.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF578FFCDB1B7F8CFAD72F8EC.taxon	description	(FIGS 4 I – J, 4 P – Q, 18 – 21)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF578FFCBB1F0F89CAD56F9F0.taxon	materials_examined	Other material examined Gyeongsangbuk-do, South Korea, 24 August 2011, onespecimen 22 mmpreserved length, leg. D. - W. Jung (CPIC 02175, isolate HG 129); 12 August 2012, one specimen 28 mm preserved length, leg. D. - W. Jung (CPIC 02179, isolate HG 133); 24 August 2012, one specimen 21 mm preserved length, leg. D. - W. Jung (CPIC 02180, isolate HG 134). Jeju-do, South Korea, 28 April 2013, one specimen 23 mm preserved length, leg. D. - W. Jung (CPIC 02176, isolate HG 130). Southern Hokkaido, Japan, 12 September 2014, one specimen 20 mm preserved length, leg. T. Lindsay (CPIC 01367, isolate HG 61). Description External anatomy: Animal elongate, wider in visceral region, narrowing gradually towards head and tail; visceral hump proportionally very large, elongate, well differentiated from rest of body, occupying more than 1 / 3 of body length; mantle foramen large, oval, on posterior left side of visceral hump, not elevated; parapodia broad, fused posteriorly, typically joined anteriorly, forming several folds; rhinophores and oral tentacles relatively short, enrolled, with small projections in oral tentacles; siphon wide, relatively short, protruding slightly above parapodia. Colour reddish to brown, with white dots aggregated in clusters; parapodia edged in red, with a broad submarginal black band, often with white dots; rhinophores and oral tentacles tips red with submarginal black area dotted in white; mantle foramen with dark inner edge. Internal anatomy: Shell broad, oval, widest near centre; posterior left side regularly curved, posterior right side concave adjacent to protoconch; rachidian tooth with robust, triangular central cusp bearing multiple sharp denticles, 3 – 4 lateral cusps on each side of central cusp, typically lacking denticles; lateral teeth with central cusp denticulated on both sides, larger tooth or secondary cusps near each side of base; up to four simple outer teeth. Radular formula 27 × 3.9.1.9. 3 in a 23 mm preserved length specimen from South Korea (CPIC 02176, isolate HG 130) and 27 × 4.9.1.9. 4 in a 21 mm preserved length specimen from South Korea (CPIC 02180, isolate HG 134). Jaw with cylindrical, elongated elements with single cusp at tips. Penis elongate, robust, with two retractor muscles and tip with a single hooked papilla.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF57DFFC6B1ADFCB4AEE4FD4D.taxon	description	(FIGS 22 – 25)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF57DFFC6B1ADFCB4AEE4FD4D.taxon	materials_examined	Additional material examined: Santander, Spain, May 2013, three specimens 8 – 22 mm preserved length (CPIC 01424, isolate HG 78). Bahía de Cádiz, Spain, 3 March 2006, one specimen 19 mm preserved length (CPIC 1359, isolate HG 24). Cap l’Abeille, Banyuls sur Mer, France, 8 - m depth, 22 May 2014, one specimen 13 mm preserved length (CPIC 01361, isolate HG 51). Gallipoli, Italy, 3 April 2009, one specimen 12 mm preserved length (CPIC 01355, isolate HG 14); 3 April 2009, one specimen 19 mm preserved length (CPIC 01358, isolate HG 26). Livorno, Italy, 19 April 2014, two specimens 12 – 16 mm preserved length (CPIC 01379, isolate HG 48). Kato Zakros, Crete, Greece, 9 April 2009, five specimens 6 – 15 mm preserved length (CPIC 02181, isolate HG 33); two specimens 11 – 14 mm preserved length (CPIC 01387, isolate HG 87). Agia Pelagia, Crete, Greece, one specimen 18 mm preserved length (CPIC 01388, isolate HG 86). Description External anatomy: Animal oval to elongate, wider in visceral region, narrowing gradually towards head and more abruptly towards tail; visceral hump proportionally very large, elongate, well-differentiated from the rest of the body, occupying about than 1 / 2 of body length; mantle foramen very large, oval, on posterior left side of visceral hump, not elevated; parapodia broad, fused posteriorly, sometimes joined anteriorly, forming several folds; rhinophores and oral tentacles relatively short, enrolled, with a small basal projections in each oral tentacle; siphon wide, relatively short, protruding slightly above parapodia. Colour pale orange to reddish-brown, with scattered large white spots, some specimens with numerous additional small white dots, others lacking white, covered with brown dots; parapodia edged in white, sometimes with a broad submarginal black or brown band, often with white dots; rhinophores and oral tentacles same colour as body, some animals with black or brown tips and white dots; mantle foramen with thin white inner edge. Internal anatomy: Shell oval, widest near mid-length; posterior end regularly curved, right slightly concave adjacent to protoconch; rachidian tooth with robust, triangular central cusp bearing multiple sharp denticles, 2 – 3 lateral cusps on each side of central cusp, typically lacking denticles; lateral teeth with central cusp denticulated on both sides, larger tooth or secondary cusps near each side of base; up to five simple outer teeth. Radular formula 30 × 4.10.1.10. 4 in an 18 mm preserved length specimen from Greece (CPIC 01388, isolate HG 86). Jaw with cylindrical, elongated elements with 1 – 2 cusps at tips. Penis very elongate, narrow, with a single retractor muscles, and simple tip, lacking papillae. Range: North-eastern Atlantic Ocean from Norway and the Baltic Sea to Macaronesia (Eales, 1960; Ávila et al., 1998, 2000; Wirtz, 1999) and throughout the Mediterranean (Eales, 1960). Remarks The name Aplysia punctata has been used for a widespread species occurring in the north-eastern Atlantic (including Greenland) from Norway to the Canary Islands, the Mediterranean and the Baltic Sea (Eales, 1960), with more recent records from the Azores (Ávila et al., 1998, 2000) and Madeira (Wirtz, 1999). Pilsbry (1895 – 96), Engel (1936) and Eales (1960) compiled a list of synonyms (listed above) and provided a comprehensive description of this species. In this study we sequenced a number of specimens collected in the Mediterranean and the Atlantic coast of Europe (including the Azores) identified as A. parvula. However, the mtDNA sequences of these specimens are similar to sequences obtained from GenBank of specimens identified as A. punctata and collected from the eastern Atlantic, as far north as Germany, but different from other specimens of the A. parvula species complexes from other regions. The only mtDNA sequences that displayed consistent differences were obtained from samples collected in the Azores that display 17 substitutions in COI versus animals from the European mainland. Thus, based on the analyses of mtDNA sequences, we cannot confirm the presence of any species of the A. parvula species complexes in the eastern Atlantic or Mediterranean with the exception of A. punctata. These results are surprising, considering the specimens sequenced from these areas were phenotypically similar to A. parvula s. l. Furthermore, the examination of the penial morphology of our specimens confirmed the presence of a single retractor muscle, also consistent with the characteristics of A. punctata. Finally, sequence data from the nDNA gene histone H 3 confirmed that most of the specimens from the Mediterranean and the Atlantic coast of Europe (including the Azores) were genetically different from other species of the A. parvula species complexes from other areas in the Atlantic Ocean and beyond. However, a specimen collected in the Azores (HG 20) and a specimen collected in Italy (HG 19) are heterozygotes, with one allele from A. punctata and another from A. ghanimii. The genetic makeup of these two individuals suggests they could constitute hybrids between these two species, although it could also be the result of incomplete lineage sorting. If hybridization is confirmed, it potentially suggests limited genetic introgression of A. ghanimii into the Mediterranean and eastern Atlantic populations of A. punctata. These results contradict the previous hypothesis (Eales, 1970; Bebbington, 1975; Bebbington & Brown, 1975) that the Mediterranean has been broadly invaded by A. parvula. If any invasion has occurred, it was a limited introgression of A. ghanimii nDNA into native A. punctata populations. Phenotypically, some Mediterranean specimens of A. punctata appear to match the external characteristics of other members of the A. parvula species complexes, but a closer examination suggests otherwise. For example, the body of the Mediterranean and Eastern Atlantic animals identified as A. parvula have shorter bodies with more triangular tails than in any other species of A. parvula s. l. It appears that the only trait linking Mediterranean and eastern Atlantic specimens with other species of the A. parvula species complexes is the external coloration. It is widely agreed that the suggested invasion of A. parvula of the Mediterranean started with Swennen’s (1961) report of specimens with a distinctive black band on the edge of the parapodia collected in Turkey. However, the penial morphology of those specimens was consistent with that of A. punctata (see Bebbington, 1977), highlighting the difficulties to properly identify these two species using morphology alone. Moreover, a review of the literature reveals that Swennen’s (1961) report was not the first Mediterranean record of A. parvula - like specimens. Risso (1818) described Aplysia nigromarginata from Nice, France, as being black in colour with a dark black rim of the mantle and dark tentacles. This description matches the colour typically described for A. parvula, including Mediterranean animals, but Eales (1960) regarded A. nigromarginata it as a synonym of A. punctata. As mentioned above, the only specimens from the Mediterranean and the eastern Atlantic that display genetic differences are those from the Azores, which form a well-supported clade (Fig. 2 A) and are recovered as a distinct species in the ABGD analysis (Table 2). Although this population probably constitutes a distinct species, it is not described herein due to a lack of complete specimens; only tissue samples were obtained.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF573FFC6B220FCB0AA04FAC9.taxon	discussion	Remarks Sowerby I (1833) proposed the name Aplysia concava based on a figure of a shell with no description and no locality. Eales (1960) considered A. concava a synonym of A. parvula. The shell of this species, illustrated in ventral view and depicted in black and white [Sowerby I, 1833: pl. 235 (155), fig. 3], is similar to shells of several species in Aplysia parvula s. l. and it is impossible for us to match it with any particular taxon. Therefore, we regard A. concava as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF573FFC6B058FCE8ABDAFC95.taxon	discussion	Remarks Bergh (1898) proposed the species name Aplysiopsis juanina in a new genus Aplysiopsis Bergh, 1898 (non Aplysiopsis Deshayes, 1853) from the Juan Fernández Islands, Chile, based on nine preserved specimens. Bergh (1898) published detailed descriptions and illustrations of the anatomy of this species, including the preserved animal, reproductive system, gill, shell, nervous system and radula. The characteristics of A. juanina resemble those of A. parvula s. l. Engel (1936) regarded A. juanina as a subspecies of A. parvula, whereas Eales (1960) considered it a synonym of A. parvula. For this study we obtained a single specimen from the Juan Fernández Islands with similar characteristics to those described in the original description of A. juanina (Bergh, 1898). This animal is genetically different and sister to all other species of A. parvula s. l. here examined (Fig. 2 B). Therefore A. juanina is regarded as a distinct species of Aplysia. SUPPRESSED NAMES The following species name was regarded as synonym of A. parvula, but is suppressed by the ICZN.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF573FFC6B058FCE8ABDAFC95.taxon	discussion	Remarks In order to preserve the name A. parvula, Eales (1959) requested the IZCN to suppress the possible older synonym A. spuria Krauss, 1848, which was used by Macnae (1955) for specimens of A. parvula s. l. Although the true identity of A. spuria [as originally described by Krauss (1848)] is uncertain, the IZCN in Opinion 560 suppressed this name under the Plenary Powers (ICZN 1959) and placed A. parvula in the Official List of Specific Names in Zoology. TAXA INQUIRENDA The following species names were regarded as synonyms of A. parvula, but the original descriptions are not sufficiently complete to allow their identification with species recognized in this study.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF573FFC7B23BFA54AE2AFD85.taxon	discussion	Remarks Sowerby II (1869) proposed Aplysia anguilla from manuscript notes by Cuming and an illustration of a shell of unknown geographic origin. The short description indicated: ‘ Shell small, tumid, strongly arched, transverse pale horn; apex rounded, small, incurved; upper margin very short, deeply excavated, acuminated at the end; outer lip obliquely produced; dorsal margin round; lower margin oblique, widely excavated. ’ The illustration of the shell (Sowerby II, 1869: pl. 6, fig. 22) represents a small, brown specimen with a curved apex. Eales (1960) considered A. anguilla a synonym of A. parvula based on shell morphology. However, in our study we have revealed the existence of several species with a similar shell morphology and it is virtually impossible to determine the identity of this species. Therefore, A. anguilla is here regarded as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF572FFC7B196FDA0AE2AFA76.taxon	discussion	Remarks Sowerby II (1869) introduced the name Aplysia norfolkensis based on a shell collected in Norfolk Island, Australia. The short description stated: ‘ Shell horny, brown, arched, ventricose, obliquely subovate, thin, smooth; apex elevated, round, auriculated at the back; upper margin sloped, excavated; outer lip rather convex; lower margin rounded, dorsal margin arched; rounded, thinly reflected near the apex, obliquely inclined towards the lower end. ’ The illustrations of the shell (Sowerby II, 1869: pl. 10, fig. 42 A – B) represent an elongate brown specimen with a curved apex, very similar to other shells of A. parvula s. l. here examined. As in the previous case, Eales (1960) considered A. norfolkensis a synonym of A. parvula based on the shell morphology. However, in this study we have revealed the existence of several species with a similar shell morphology and it is virtually impossible to determine the identity of this species. Therefore, A. norfolkensis is here regarded as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF572FFC7B18BF9D5AA81FDC0.taxon	description	(FIGS. 4 N – O)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF572FFC7B18BF9D5AA81FDC0.taxon	discussion	Remarks Sowerby II (1869) described Aplysia orientalis based on a shell collected in the ‘ Chinese Seas’. After the brief description, Sowerby II (1869) indicated: ‘ This shell nearly resembles Aplysia punctata in form, although less triangular. It has a slight bluish tint in colouring. ’ We have examined photographs of one of the syntypes (NHMUK 1958.1.9.270 - 1) (Fig. 4 N – O), which do not match the general characteristics of the shell of A. japonica, the only species studied here found in that region. However, the shell of A. orientalis is much broader and more triangular than those of the type material and other specimens of A. japonica. Eales (1960) considered A. orientalis a synonym of A. parvula. However, based on the observation of the type material we cannot confirm this synonymy and we here regard A. orientalis as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF572FFC7B232FD6FAA4CFA57.taxon	discussion	Remarks Sowerby II (1869) proposed the name Aplysia subquadrata based on a manuscript description by Gould (see also: Tryon, 1868) and illustrations of the shell collected in the ‘ United States’. In the short remarks after the description, Sowerby II (1869) indicated: ‘ The shell of this species is not easily distinguished from that of the British and Mediterranean Aplysia hybrida [= A. punctata]. ’ Tryon (1868) and Pilsbry (1895 – 96) regarded A. subquadrata a synonym of A. punctata, whereas Eales (1960) considered A. subquadrata a synonym of A. parvula. Because of the vague type locality information, we are unable to determine whether A. subquadrata is an Atlantic or Pacific species. Aplysia parvula s. l. is present on both coasts of the United States, although only marginally and recently recorded from San Clemente Island, California (Behrens & Hermosillo 2005), close to the Mexican border. Based on the information provided in the original description we are unable to determine the identity of this species.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF572FFC4B2D2F9F3ADFBFE3A.taxon	discussion	Remarks Sowerby II (1869) described Aplysia trigona based on a shell of undetermined origin. The shell illustrated (Sowerby II, 1869: pl. 4, fig. 11) is clearly rhomboid and different from the shells of other species here examined. Sowerby II (1869) indicated: ‘ This species resembles Aplysia punctata in colour, texture, and convexity, but differs from them in its triangular form. ’ Eales (1960) regarded A. trigona as a possible synonym of A. parvula, but with the available data we are unable to determine the identity of this species.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF571FFC4B2D4FB24ABFFF91C.taxon	discussion	Remarks Clessin (1899) introduced the name Aplysia australiana based on a shell collected in Australia. The short description and illustration matches the characteristics of other shells of A. parvula s. l., as indicated by Eales (1960). But due to the lack of additional details, we are unable to determine the identity of this species and, therefore, we regard A. australiana as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF571FFC4B05EFA09AA40FB19.taxon	description	(FIG. 4 C – D)	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF571FFC4B05EFA09AA40FB19.taxon	discussion	Remarks Pease (1868) described Syphonota punctata from Huahine, Society Islands, based on a specimen described as: ‘ Pale fawn, mottled with darker, and covered with minute crowded white and very light purple dots; under portion of the body, edges of the mantle and labial tentacles margined with dark slate color. ’ Pease (1868) did not provide any internal anatomical details. Pilsbry (1895 – 96) noted that S. punctata is a secondary homonym of Aplysia punctata Cuvier, 1804 and proposed the replacement name Tethys peasei Pilsbry, 1895. Eales (1960) regarded T. peasei as a synonym of A. parvula. The original description of Syphonota punctata is brief but includes important details of the external morphology and colour, as well as an illustration of the live animal (Pease 1868: pl. 9, fig. 2). This pattern of coloration is inconsistent with that of other species of A. parvula s. l. described here, with the exception of the presence of a dark margin of the parapodia. Also, the parapodia of S. punctata are represented as wide and straight, not forming the loops typically found in A. parvula s. l. The presence of numerous, small black rings represented in the illustration of S. punctata (Pease 1868: pl. 9, fig. 2) resemble the pattern of Aplysia oculifera A. Adams & Reeve, 1850 (see: Gosliner et al., 2015), but differs by having dark spots on the rhinophores. We have examined the shell of a syntype of S. punctata (MCZM 297868) (Fig. 4 C – D), which resembles the characteristics of other species of A. parvula s. l. suggesting this name could be a synonym of one of the species described herein. However, because of the inconsistencies described above, we are unable to confidently identify this species with any members of A. parvula s. l. and, therefore, we regard it as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF571FFC4B18EFE19AD01FA2B.taxon	discussion	Remarks Meinertzhagen (1880) proposed Aplysia tryonii based on a 5 - in long specimen with no illustrations and described it as: ‘ Dark brown (kelp colour), spotted all over with grey pepper coloured spots, ’ … ‘ the edges of the lower lobe of the mantle marked evenly darker brown and grey, ’ … ‘ the lobe covering the shell striped of which stripes point to, and narrow towards, the apex of the shell’ and ‘ posterior sides of upper tentacles also a peppery grey colour. ’ This description is ambiguous, but the large size of the specimen indicates it is unlikely that A. tryonii is a member of any of the species included in A. parvula s. l. To highlight the confusion around this name, Eales (1960: 273) included A. tryonii in a list of invalid or of doubtful validity (= nomen dubium) names, but at the same time mentioned that it is possible that A. tryonii is a synonym of A. parvula (Eales, 1960: 287). Eales (1960: 291) also commented that specimens described and illustrated by Suter (1913: 545, pl. 36, fig. 6) as A. tryonii are probably A. parvula. While it looks evident that at least one species of A. parvula s. l. is present in New Zealand, due to the large size of the holotype, it is very unlikely A. tryonii belongs to this group and therefore it is here regarded as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF571FFC5B2C3F93BAE91FDDA.taxon	discussion	Remarks Clessin (1899) briefly described Aplysia paeteliana based on a shell of unknown origin. Clessin (1899) also mentioned that this species is the same as the shell identified as A. marginata (= A. punctata) by Friedrich Paetel and deposited at the Berlin Museum, but it is different from the true A. marginata sensu Blainville (1823) and Sowerby II (1869) (cited as Reeve Conch. icon. fig. 15). Eales (1960) considered A. paeteliana as a synonym of A. parvula. However, as in the previous species, the lack of detail in the original description prevents us from determining the identity of this species and, therefore, we regard A. paeteliana as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF570FFC5B059FD61AE4FFA49.taxon	discussion	Remarks Farran (1905) described Aplysia intermedia based on a single specimen from Sri Lanka. The live animal was described as green, greyish, preserved. The mantle foramen was large, but did not have a black edge, and the parapodia were described as long and free. The tentacles were large, produced anteriorly into broad labial flaps. The radular teeth were illustrated and briefly described. Eales (1960) considered A. intermedia as a synonym of A. parvula. While it is clear that A. intermedia belongs to A. parvula s. l., we are unable to determine to what species and, therefore, we regard A. intermedia a taxon inquirendum. Based on the original description (specifically the large mantle foramen with no black outline, the large parapodia, the broad labial flaps, and the reduced number of radular outer teeth), it could belong to Aplysia ghanimii, which is represented in the Indian Ocean, but this cannot be confirmed with certainty due to the absence of molecular data.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF570FFC5B07FF9D4ABD0FC51.taxon	discussion	Remarks Bergh (1908) introduced the name Aplysia lobata based on a single specimen collected from Woodstock Beach, Table Bay, Cape Town, South Africa, which no longer exists after the land reclamation of Table Bay in the 1950 s to create the Cape Town foreshore (Worden 1994). Bergh (1908) described the species providing numerous details of the external and internal anatomy, but no descriptions of the live animal. The identity of this species is controversial; Eales (1960) placed A. lobata in synonymy of A. parvula but at the same time commented it could be a juvenile A. dactylomela Rang, 1828. Although Bergh’s (1908) description of A. lobata is very detailed, we cannot positively identify this species. The radular teeth included only three outer laterals and the jaw elements have a single cusp. However, the penis was not fully dissected and was illustrated within the penial sheath. Bergh (1908) also indicated that the parapodia had a curious lobed shape, so symmetrical that it would be unlikely to be the result of mutilation. A similar lobe is found in live species of the Aplysia elongata-nigrocincta complex, which also have a similar radular morphology to that of A. lobata. However, because of the absence of detailed penial descriptions, we hesitate to place A. lobata in synonymy of any other species in the A. elongata-nigrocincta complex. The original type material of A. lobata is probably lost, which further hampers our ability to identify this species. Therefore, we regard A. lobata as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF570FFC5B2F4FBFCACCDF8C4.taxon	discussion	Remarks Bergh (1908) proposed the name Aplysia monochroa based on two specimens collected in Hermanus, South Africa. Bergh’s (1908) description included details of the shell and other internal anatomical characteristics of the two preserved specimens. Bergh (1908: pl. 1, figs 22 – 24, pl. 2, figs 2 – 7) included figures of the radulae, jaws and penis. The penis is conical, elongate, has two strong retractor muscles and a short deferent duct. This is most similar to the penial morphology in the three species of the Aplysia parvula – atromarginata complex. On the contrary, the simple jaw elements and the presence of only 2 – 3 outer lateral radular teeth are more consistent with the characteristics of members of the Aplysia elongata – nigrocincta species complex. Because of these ambiguities, and lack of original type material, we cannot determine the identity of A. monochroa with certainty, which we thus regard as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF577FFC2B051FF0DAD88FCA1.taxon	discussion	Remarks Bergh (1908) described Aplysia allochroa in great detail, including descriptions of two preserved specimens collected in Knysna, South Africa. Eales (1960) placed A. allochroa in the synonymy of A. parvula, but anatomical descriptions by Bergh (1908) are not consistent with this assessment. First of all, the shell of A. allochroa is much broader than the shells of A. parvula s. l. described herein. Additionally, the penis of A. allochroa has a single retractor muscle, different from all other species of A. parvula s. l., which have two. Thus, we are confident A. allochroa is not one of the species of A. parvula s. l., but we are unsure of its identity.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF577FFC2B050FC9DAE38F925.taxon	discussion	Remarks Thiele (1925) introduced Aplysia peregrina based on a single preserved specimen collected during the Valdivia Expedition, but with no locality data (but likely from the Indian Ocean). According to Thiele (1925), the specimen was contracted into a ballshaped mass, was covered with numerous roundish bright spots and the parapodia had black plump spots on the edge. The shell was illustrated [Thiele, 1925: pl. 33 (45), fig. 4] and briefly described, but no other details of the internal anatomy of this species were provided. Unfortunately, the holotype has been partially destroyed and only a piece of damaged tissue remains at the ZMB collections (Christine Zorn, pers. comm.). Eales (1960) considered A. peregrina a possible synonym of A. parvula. However, because of the lack of details in Thiele’s (1925) original description, and in the absence of type material, we cannot determine the identity of A. peregrina, which we regard as a taxon inquirendum.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
038987ACF577FFC0B23AF8C4AD9FFD85.taxon	description	Contrary to published reports, we have found no evidence of widespread presence of A. parvula s. l. in the Mediterranean Sea. Multiple specimens identified as A. parvula collected across the entire Mediterranean basin, as well as adjacent areas in the eastern Atlantic, were sequenced and examined morphologically. Whereas externally those specimens possess a dark parapodial margin and are similar to animals previously identified as A. parvula, in phylogenetic analyses they cluster with animals identified as A. punctata and collected as far away as northern Europe. Anatomically, the penial morphology of all Mediterranean animals examined is also consistent with that of A. punctata, having only one retractor muscle. Sequence data from the nDNA gene histone H 3 provided similar results: A. punctata is distinct from all specimens of A. parvula s. l. sequenced in this study and the genetic makeup of the great majority of specimens from the Mediterranean and the eastern Atlantic is consistent with that of A. punctata. However, two specimens collected in the Azores, Portugal (HG 20) and Gallipoli, Italy (HG 19) were heterozygotes with one A. punctata allele and one allele from A. ghanimii (Supporting Information, Fig. S 1). One plausible explanation is that these two specimens are hybrids and if this is confirmed it would imply asymmetric genetic introgression of A. ghanimii into A. punctata, because the mtDNA of these two specimens is consistent with that of A. punctata. While we found no evidence of the proposed presence of A. parvula s. l. in the Mediterranean or the north-eastern Atlantic, with the exception of two nDNA sequences, it is clear (based on a review of the literature) that the A. parvula phenotype, namely small Aplysia punctata specimens with a dark parapodial edge, have become common in the Mediterranean. We cannot provide a definitive explanation for this observation, but there are several possibilities. Because the colour pattern of A. parvula s. l. and A. punctata is so variable, it is possible that it is influenced by environmental factors such as temperature or diet. If that is the case, the tropicalization of the Mediterranean (Francour et al., 1994; Bombace 2001; Morri et al., 2001; Golani et al., 2002; Gofas & Zenetos, 2003) or the arrival of non-native seaweed species (e. g. Verlaque et al., 2015; Zenetos et al., 2017) may have resulted in the A. punctata phenotype becoming more similar to that of A. parvula s. l. One problem with this hypothesis is that the A. punctata phenotype persists in the Mediterranean. One of us (MS) has observed hundreds of egg-laying A. punctata in Croatia over the years; these animals are large (up to 200 mm when crawling) and display the typical A. punctata phenotype. These animals co-exist with smaller (~ 20 mm), sexually mature animals displaying the A. parvula phenotype, as observed by another one of us (JL). Another possibility is a more widespread introgression of A. parvula s. l. genes coding for pigmentation into A. punctata. Such an introgression would not have been detected in a study exclusively targeting a histone gene. Testing these hypotheses will require additional research, including more in-depth sequencing of Mediterranean animals using RAD-seq technology and / or ‘ common garden’ experiments to investigate the influence of the environment on colour pattern and size. Both are well beyond the scope of this paper. The results of this and other recent papers highlight the need for careful molecular and anatomical studies to understand the origin and dispersal of non-native species. The only three alien species of sea hares found in the Mediterranean (B. leachii, A. dactylomela and A. parvula) were hypothesized to have a Red Sea origin. Two of them, B. leachii and A. dactylomela, were found to have an Atlantic origin (Valdés et al., 2013; Bazzicalupo et al., 2018) and the case of A. parvula is most likely an example of mistaken identity.	en	Golestani, Haleh, Crocetta, Fabio, Padula, Vinicius, Camacho-García, Yolanda, Langeneck, Joachim, Poursanidis, Dimitris, Pola, Marta, Yokeş, M. Baki, Cervera, Juan Lucas, Jung, Dae-Wui, Gosliner, Terrence M., Araya, Juan Francisco, Hooker, Yuri, Schrödl, Michael, Valdés, Ángel (2019): The little Aplysia coming of age: from one species to a complex of species complexes in Aplysia parvula (Mollusca: Gastropoda: Heterobranchia). Zoological Journal of the Linnean Society 187: 279-330
