Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau Author Gil, Marta 0000-0002-8985-332X Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar e Centro de Investigación Mariña (CIM-Uvigo), Universidade de Vigo. Campus Lagoas-Marcosende. 36310 Vigo. Spain & martag @ uvigo. gal; https: // orcid. org / 0000 - 0002 - 8985 - 332 X martag@uvigo.gal Author Ramil, Fran 0000-0002-9146-8201 Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar e Centro de Investigación Mariña (CIM-Uvigo), Universidade de Vigo. Campus Lagoas-Marcosende. 36310 Vigo. Spain & Departamento de Ecoloxía e Bioloxía Animal, Facultade de Ciencias do Mar e Centro de Investigación Mariña (CIM-Uvigo), Universidade de Vigo. Campus Lagoas-Marcosende. 36310 Vigo. Spain & framil @ uvigo. gal; https: // orcid. org / 0000 - 0002 - 9146 - 8201 * Corresponding author framil@uvigo.gal text Zootaxa 2025 2025-01-29 5577 1 1 89 https://doi.org/10.11646/zootaxa.5577.1.1 journal article 10.11646/zootaxa.5577.1.1 1175-5334 14763362 A5924C49-3957-4A8A-BD8E-D0FE741D6B1F Tridentata marginata ( Kirchenpauer, 1864 ) ( Fig. 9B–D ) Dynamena marginata Kirchenpauer, 1864: 13 , fig. 8. Tridentata marginata : Calder, 1991: 107–109 , figs 56, 57.— Calder, 2013: 31–33 , fig. 9E–F. Sertularia marginata : Leloup, 1939: 422 , fig. 4.— Buchanan, 1957: 367 .—Millard, 1975: 311–312, fig. 99A–D.— Migotto, 1996: 73–75 , fig. 14A–C.— Medel & Vervoort, 1998: 66–70 , figs 20C, 22.—Galea, 2015: 12, fig. 3Q–R. Sertularia versluysi : Ritchie, 1907: 505–507 , text–fig. 144, pl. XXIV figs 2–6. Material examined. BISSAU-0810, stn BS191, 10º18'25"– 10º19'20"N , 16º08'47"– 16º08'47"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 BS192, 10º19'30"– 10º20'15"N , 16º10'27"– 16º10'59"W , 24 m , 3-XI-2008 : five colonies without gonothecae, 40–155 mm high, substrate unknown. BISSAU-0810, stn BS193, 10º21'13"– 10º21'51"N , 16º10'17"– 16º10'56"W , 20–21 m , 3-XI-2008 : one colony without gonothecae, 96 mm high, substrate unknown. BISSAU-0810, stn BS194, 10º21'59"– 10º22'36"N , 16º13'23"– 16º14'03"W , 21–24 m , 3-XI-2008 : four colonies without gonothecae, 55–75 mm high, substrate unknown. BISSAU-0810, stn BS195, 10º22'44"– 10º23'22"N , 16º15'37"– 16º16'18"W , 29 m , 3-XI-2008 : six colonies (five with gonothecae), 27–130 mm high, substrate unknown. BISSAU-0810, stn BS199, 10º16'49"– 10º17'29"N , 16º22'15"– 16º22'49"W , 65–70 m , 4-XI-2008 : one colony without gonothecae, 81 mm high, substrate unknown. Remarks. Differences between T. marginata and Tridentata turbinata ( Lamouroux, 1816 ) were pointed out by Calder (2013) , and also discussed by Gil & Ramil (2023b) . Our finding represents the first record of this species for Guinea-Bissau . 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. 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 1906a , 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 .