Taxonomy and diversity of hydroids (Cnidaria: Hydrozoa) of Sergipe, Northeast Brazil Author Castro Mendonça, Luana M. Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Alagoas. Avenida Lourival Melo Mota, & Programa de Pós-Graduação em Zoologia, Departamento de Zoologia, Setor de Ciências Biológicas, Universidade Federal do Paraná. Caixa Postal 19020, 81531 - 980 Curitiba, PR, Brazil. mahaddad. 2014 @ gmail. com Author Parisotto Guimarães, Carmen R. Departamento de Biologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe. Avenida carmenparisotto@gmail.com Author Haddad, Maria A. Instituto de Ciências Biológicas e da Saúde, Universidade Federal de Alagoas. Avenida Lourival Melo Mota, text Zoologia 2022 e 21032 2022-11-25 39 1 65 http://dx.doi.org/10.1590/s1984-4689.v39.e21032 journal article 10.1590/S1984-4689.v39.e21032 1984-4689 13176475 2B189EA2-803A-428C-AE26-C3669A5F3100 Tridentata turbinata ( Lamouroux, 1816 ) Fig. 22G–H Synonyms available from: Calder (1991) , Medel and Vervoort (1998) and Calder (2008). Dynamena turbinata Lamouroux, 1816: 180 . Sertularia turbinata – Migotto, 1996: 78 , fig. 14F, G. Geminella ceramensis – Vannucci Mendes, 1946: 570 . Description: Colonies erect, up to 15.2 mm high, unbranched, arising from a creeping hydrorhiza. Stem ahydrothecate at the base, internode separated by an oblique hinge, the others by slightly oblique nodes. Long internodes each with a pair of opposite hydrothecae. Hydrothecae short, 0.15–0.22 mm high, 0.13–0.15 mm maximum diameter, inflated at halfway their basal portion, adnate to the stem less than half their height, free portion curving outwards. Abcauline wall is almost straight at the half basal portion, and slightly concave at the curvature. Adcauline wall convex in the adnate portion and straight to perpendicular in the free portion. In some hydrothecae, it is possible to see a crossed line of perisarc at the curvature of the adcauline wall. A perisarc thickening horseshoe shape is visible at the curvature of the abcauline wall, projecting toward the center of the hydrothecae. Margin hydrothecal with three cusps, two wide laterals, and one small median adcauline. Operculum with two valves, one wide and one small. Nematocysts microbasic mastigophores? undischarged (8.2–10.1 × 2.4–3 µm), in hydranth and coenosarc. Material examined: PCS – few infertile colonies from the rainy season. CZUFS CNI-00221. Stations: PCS – 5, 12, 15. Bottom: gravel and sand. Distribution: The species has been recorded as Sertularia turbinata and Tridentata turbinata in Brazil . Brazil – Pernambuco ( Calder and Maÿal 1998 ), Fernando de Noronha ( Amaral et al. 2009 ), Espírito Santo ( Grohmann et al. 1997 , 2003 ), Rio de Janeiro ( Nogueira et al. 1997 , Grohmann et al. 2003 ), São Paulo ( Oliveira et al. 2006 , Cunha and Jacobucci 2010 , Oliveira and Marques 2011 , Silveira and Morandini 2011 , Marques et al. 2013 ), Paraná (Maria A. Haddad unpub. data), and Santa Catarina ( Miranda et al. 2011 , Bouzon et al. 2012 ). World distribution – circumglobal from tropical to subtropical regions ( Millard 1975 ). Taxonomic remarks: According to Calder (2019) this species has long been misassigned to a non-monophyletic genus Sertularia Linnaeus, 1758 instead of Tridentata Stechow, 1920 . Remarks: All colonies were on algae.