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 Diphasia tropica Nutting, 1904 Fig. 21F Synonyms available from: Migotto (1996) . Diphasia tropica Nutting, 1904: 110 . Diphasiella ornata Vannucci, 1949: 239 . Description: Colonies erect, up to 14.2 mm high, arising from a creeping hydrorhiza. Stem monosiphonic, unbranched, divided into two regions, the basal portion ahydrothecate, separated by an oblique node, and the other larger portion composed by internodes successively with and without paired hydrothecae, also separated by oblique nodes. Hydrothecae tubular, narrower in the basal portion, expanding a little to the middle part, 0.49–0.54 mm high and 0.15–0.17 mm maximum diameter, adnate to stem and in contact to each other over half their high, free part facing outside. Hydrothecal perisarc with several circular transverse grooves. Margin smooth, opening square, operculum with one valve. Material examined: PCS – few infertile colonies from the dry and rainy seasons. CZUFS CNI-00208; CNI-00309; CNI-00310; CNI-00311. Station: PCS – 5, 6, 8. Bottom: gravel, sand, and mud. Distribution: Brazil – Espírito Santo ( Vannucci 1949 , 1951a , Grohmann et al. 1997 , 2003 ), Rio de Janeiro ( Nogueira et al. 1997 , Miranda et al. 2015 ), São Paulo ( Migotto 1996 , Oliveira et al. 2006 , Silveira and Morandini 2011 , Miranda et al. 2015 ), and Santa Catarina ( Bouzon et al. 2012 ). World distribution – species with records from Western and Eastern Atlantic ( Calder 1991 ). Remarks: Found on algae. Dynamena crisioides Lamouroux, 1824 Fig. 21I Synonyms available from: Calder (1991) . Dynamena crisioides Lamouroux, 1824: 613 , pl. 90, fig. 11, 12, – Pires et al., 1992: 6 , – Migotto, 1996: 60 , figs 11E–G. Dynamena crisioides f. typica Vannucci Mendes, 1946: 557 , pl. 3, fig. 24, 25, – Vannucci, 1949: 243 , 1954: 115 . Description: Colonies erect, up to 31 mm high, arising from a creeping hydrorhiza. Stem monosiphonic, divided into internodes by transverse nodes. Basal stem segments ahydrothecate, upper part with successive pairs of hydrothecae. Each internode with a proximal hydrocladium, an axillary hydrotheca, and one to three successive pairs of hydrothecae. Only the distal adnate portion of the axillary hydrotheca reaches the base of the subsequent one. Hydrothecal pairs separated along the adnate side. Hydrocladia 7.9–9.6 mm long, arising from a short, straight, or slightly curved apophysis at angles of 127.3–148.6 ° , divided into internodes of different sizes by transverse nodes. Hydrothecae tubular, elongated, 0.41–0.55 mm high, 0.11–0.16 mm maximum diameter, adnate for more than half their high, curving outwards in the distal portion. Adcauline wall of hydrothecae convex, abcauline straight or slightly concave. Margin with two lateral wide triangular cusps, rounded at the end, and one short median adcauline. Operculum with two valves, one wide abcauline and one smaller adcauline. Gonotheca vase-shaped, 0.97 mm high, 0.46 mm wide, smooth, borne on a short pedicel at the base of stem between the first pair of hydrothecae. Material examined: PCS – one infertile colony from the rainy season; VB – few infertile colonies from the dry and rainy seasons; SE – few colonies from the dry season, one of them with one gonotheca. CZUFS CNI-00027; CNI-00063; CNI-00209; CNI-00210. Stations: PCS – 7; VB – C1P34, C1P56, C2P34, C2P56; SE – C1P34, C1P56, C2P12, C2P34, C3P12. Bottom: mud. Distribution: Brazil – Ceará ( Marques et al. 2006 ), Fernando de Noronha ( Pires et al. 1992 , Amaral et al. 2009 ), Paraíba (Felipe F. Campos unpub. data), Pernambuco ( Calder and Maÿal 1998 , Oliveira et al. 2009 , abstract), Alagoas (Maximiliano M. Maronna unpub. data), Bahia ( Nutting 1904 ), Espírito Santo ( Grohmann et al. 1997 ), Rio de Janeiro ( Nogueira et al. 1997 , Miranda et al. 2015 ), São Paulo ( Vannucci Mendes 1946 , Vannucci 1951a , Migotto 1996 , Silveira and Morandini 2011 , Miranda et al. 2015 ), Paraná ( Miranda et al. 2015 , Maria A. Haddad unpub. data), and Santa Catarina ( Miranda et al. 2015 ). World distribution – circumglobal in tropical and subtropical regions ( Calder 1991 ). Remarks: Unknown substrate to the PCS material. Estuarine colonies were colonizing the plates, barnacles, ostreids, and ascidians.