Tridentata loculosa Busk, 1852

Castro Mendonça, Luana M., Parisotto Guimarães, Carmen R. & Haddad, Maria A., 2022, Taxonomy and diversity of hydroids (Cnidaria: Hydrozoa) of Sergipe, Northeast Brazil, Zoologia (e 21032) 39, pp. 1-65 : 52-55

Tridentata loculosa Busk, 1852

Fig. 22B

Synonyms available from: Migotto (1996) and Galea (2008).

Sertularia loculosa Busk, 1852: 393 , pl. 19, fig. 9. – Migotto, 1996: 71, fig. 13F–I.

Sertularia loculosa – Vannucci Mendes, 1946: 564.

Description: Colonies stolonal up to 1.5 mm, and erect up to 33 mm high, arising from a creeping hydrorhiza. Stem monosiphonic, branched or not, divided into internodes by transverse nodes. The first internodes ahydrothecate, the others with a pair of hydrothecae, adnate to the stem by almost all their length. Hydrothecae tubular, short and wide, appearing triangular in front view, 0.25–0.28 mm high, 0.12–0.14 mm in maximum width, free only at the distal end and directed forward. Abcauline wall with an intrathecal septum extending for almost its entire diameter of the hydrothecae, but not touching the adcauline wall. Hydrothecal margin rounded, with two large lateral cusps and one small adcauline one. Operculum with two valves, a large abcauline, and a small adcauline one.

Material examined: PCS – few infertile colonies from the dry and rainy seasons. CZUFS CNI-00030; CNI-00214; CNI-00215.

Stations: PCS – 11, 12, 13.

Bottom: gravel, sand, and mud.

Distribution: Brazil – Espírito Santo ( Vannucci 1951a, Grohmann et al. 1997), Rio de Janeiro ( Nogueira et al. 1997, Miranda et al. 2015), São Paulo ( Vannucci 1951a, Migotto 1996, Oliveira et al. 2006, Oliveira and Marques 2011, Silveira and Morandini 2011, Miranda et al. 2015), and Santa Catarina ( Bouzon et al. 2012, Miranda et al. 2015, Alaja-Batista et al. 2020). World distribution – it seems to be a circumglobal species ( Migotto 1996), widely recorded in tropical and subtropical regions of Indian and Pacific Oceans, and also with records in the Atlantic coast ( Galea 2008).

Taxonomic remarks: The generic affinities of T. loculosa are presently unclear; it has been assigned temporarily to Tridentata Stechow, 1920 given the general resemblance of its trophosome and gonosome to species of that genus ( Calder and Faucci 2021).

Remarks: Found on Hincksella formosa and Sertularelloides cylindritheca .

Tridentata marginata (Kirchenpauer, 1864) Fig. 22C–E

Synonyms available from: Calder (1991), Vervoort (1993), and

Migotto (1996). Sertularia marginata Kirchenpauer, 1864: 13 , fig. 8A–C, Vannucci

Mendes, 1946: 567, Pires et al., 1992: 7, Migotto, 1996: 73,

fig. 14A–C, Migotto, 1998: 1, fig. 1, 2. Sertularia marginata f. typica Vannucci, 1949: 248, 1951a: 84. Sertularia marginata f. laxa Vannucci, 1949: 248, 1950: 88; 1951a:

84. Sertularia inflata Maÿal, 1973: 34 .

Description: Colonies erect, up to 40 mm high, arising from a creeping tubular hydrorhiza. Stem monosiphonic, divid- ed into internodes by transverse nodes. Basal part of the stem ahydrothecate, separated from the upper part by an oblique hinge. Each internode of the remaining part of the stem with a proximal apophysis gives rise to a hydrocladium, one axillary hydrotheca, and a pair of sub-opposite hydrothecae at the distal end. This latter pair of hydrothecae adnate to the frontal region of the stem. Hydrocladia 2.9–14.8 mm high, arising from the stem at angles of 100–139 °, divided into internodes by oblique nodes. Hydrocladia internodes separated by a hinge, each one with a pair of opposite hydrothecae, except the basal internode which has no hydrothecae. Hydrothecae inflated, 0.21–0.25 mm high and 0.09–0.11 mm in maximum width. Each opposite hydrothecal pair is positioned in front of the hydrocladium, adnate to it for almost their entire length. Both hydrothecal inner front walls were in contact, and with the free distal portion curved forward. Abcauline wall with an intrathecal septum at the curvature of the hydrothecae, directed towards the adcaulinar margin, but not reaching it. Hydrothecal margin with two wide lateral cusps and a smaller median adcauline. Opening oval, operculum with two valves, one abcauline wide and a smaller adcauline divided in half. Gonothecae cylindrical, elongated, 1.4–2.9 mm high, 0.8–1.5 mm in maximum width, with several perisarcal annulations and two distal spines.

Material examined: PCS – several colonies, three of them with gonothecae, from the dry and rainy seasons. CZUFS CNI-00031; CNI-00216; CNI-00366; CNI-00367; CNI-00370.

Stations: PCS – 1, 2, 5, 6, 11, 12, 13, 16.

Bottom: gravel, sand, and mud.

Distribution: The species has been recorded as Sertularia marginata and Tridentata marginata in Brazil. Brazil – Ceará ( Marques et al. 2006), Fernando de Noronha ( Pires et al. 1992, Amaral et al. 2009), Bahia ( Grohmann et al. 2003, 2016), Pernambuco ( Calder and Maÿal 1998), Alagoas (Maximiliano M. Maronna unpub. data), Espírito Santo ( Vannucci 1950, Grohmann et al. 1997, 2003), Rio de Janeiro ( Vannucci 1950, Nogueira et al. 1997, Grohmann et al. 2003, Miranda et al. 2015), São Paulo ( Vannucci Mendes 1946, Migotto 1996, Oliveira et al. 2006, Cunha and Jacobucci 2010, Oliveira and Marques 2011, Silveira and Morandini 2011, Marques et al. 2013, Fernandez et al. 2014, Miranda et al. 2015), Paraná ( Vannucci Mendes 1946, Miranda et al. 2015, Maria A. Haddad unpub. data), and Santa Catarina ( Shimabukuro 2007, Miranda et al. 2011, 2015, Bouzon et al. 2012). World distribution – circumglobal in tropical and subtropical regions of Atlantic, Pacific, and Indian Oceans ( Vervoort 1993), considered alien from Mediterranean (González-Duarte et al. 2013).

Remarks: The material was fragmented in most of the samples. Few colonies found with hydrorhizae were colonizing algae and the hydroid Thyroscyphus ramosus .

Tridentata rugosissima (Thornely, 1904) Fig. 22F, I

Synonyms available from: Migotto (1996) and Galea (2008).

Sertularia rugosissima Thornely, 1904: 118 , pl. 2, fig. 4, – Migotto, 1996: 75, fig. 14D, E.

Geminella subtilis Vannucci Mendes, 1946: 572 , pl. 4, fig. 42, 43.

Sertularia sp. – Pires et al., 1992: 7.

Description: Colonies erect, up to 12 mm high, arising from a creeping and tubular hydrorhiza. Stem monosiphonic, unbranched, divided into internodes by oblique nodes. The first internode short, ahydrothecate, separated from the others by an oblique hinge. The other cauline internodes with a pair of opposite hydrothecae. Hydrothecae short, 0.68–0.90 mm high, 0.27–0.34 mm in maximum width, positioned in front of the stem, adnate to it in almost all its length, short distal portion free facing upwards. The lateral adnate portion of the hydrothecal pair in contact with each other. Hydrothecae wall with numerous transverse annulations (characteristic of this species), except in the distal portion. Margin smooth, with three cusps, two laterals, and a small adcauline. Operculum with two valves, a large abcaulinar, and a small adcaulinar one, usually divided in half.

Material examined: PCS – few infertile colonies from the dry and rainy seasons. CZUFS CNI-00373; CNI-00374.

Stations: PCS – 5, 6, 11, 12.

Bottom: gravel, sand, and mud.

Distribution: Brazil – Fernando de Noronha ( Pires et al. 1992), Pernambuco ( Oliveira et al. 2009, abstract, Amaral et al. 2010), Alagoas (Maximiliano M. Maronna unpub. data), Espírito Santo ( Grohmann et al. 1997), Rio de Janeiro ( Vannucci 1954, Nogueira et al. 1997), São Paulo ( Vannucci Mendes 1946, Migotto 1996, Oliveira et al. 2006, Silveira and Morandini 2011, Miranda et al. 2015), Paraná ( Vannucci Mendes 1946, Miranda et al. 2015, Alaja-Batista et al. 2020, Maria A. Haddad unpub. data), and Santa Catarina ( Miranda et al. 2015).World distribution – circumglobal from tropical to subtropical regions ( Medel and Vervoort 1998).

Taxonomic remarks: The species has been recorded as Sertularia rugosissima in Brazil.

Remarks: Found on algae, Bryozoa, and a thyroscyphid hydroid.

Figures

Figure 22. (A) Salacia tetracythara: general view of a stem showing few hydrocladia and hydrothecae; (B) Tridentata loculosa: detail of the stem with two hydrocladia and few hydrothecae; (C-E) Tridentata marginata: (C) general view of a stem with two gonothecae (red arrows); (D) detail of a stem with few hydrocladia and hydrothecae; (E) detail of one gonotheca; (F, I) Tridentata rugosissima: (F) detail of one pair of hydrothecae; (I) general view of a stem with several hydrothecae; (G-H) Tridentata turbinata: (G) detail of one pair of hydrothecae; (H) detail of a stem with hydrothecae.