Hydroids (Cnidaria, Hydrozoa) from Mauritanian Coral Mounds Author Gil, Marta 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. & Instituto Español de Oceanografía, Centro Oceanográfico de Vigo. Subida Radio Faro 50. 36390 Vigo. Spain. Author Ramil, Fran 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. es Author Agís, José Ansín 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. & ansinjose @ gmail. com text Zootaxa 2020 2020-11-16 4878 3 412 466 journal article 7931 10.11646/zootaxa.4878.3.2 288c6fc9-269b-468f-8811-d79d4350f6e4 1175-5326 4425132 4F59F5B2-CFDB-4819-AF83-0EF232328F8D Halecium tenellum Hincks, 1861 Halecium tenellum : Cornelius, 1975: 409–411 , fig. 12; Ramil & Vervoort, 1992: 90–91 , fig. 21f, g; Cornelius, 1995a: 296-297 , fig. 69; Peña Cantero & García Carrascosa, 2002: 75–77 , fig. 12c–e; Vervoort, 2006: 254 . Material examined. MAURIT-0911, stn MUDR01 , 16º08´24”N , 16º57´12”W , 488 m , 5-XII-2009 : one colony, attached to Lophelia pertusa , no gonothecae . Biology. This species has been found growing frequently on other hydroids and on rocks, pebbles and as epibiont on algae and a wide range of invertebrates ( Peña Cantero & García Carrascosa 2002 ). Fertile material has been found in January, April, May, June, October and December ( Peña Cantero & García Carrascosa 2002 ; Medel & Vervoort 2000 ). The colony studied by us was growing on L. pertusa . Distribution. Halecium tenellum is a near cosmopolitan species ( Cornelius 1975 ), with records in all oceans, including polar waters. Its distribution was reviewed in detail by Medel & Vervoort (2000) , but some identifications from high latitudes in the North Atlantic are erroneous ( Calder 1991 ; Schuchert 2005 ). In West Africa, it was collected from Morocco ( Patriti 1970 ; Ramil & Vervoort 1992 ), Canary Islands ( Vervoort 2006 ), Mauritania ( Gil & Ramil 2017a ), Cape Verde Islands ( Medel & Vervoort 2000 ; Vervoort 2006 ), Guinea-Bissau (Vervoort 1959; Gili et al . 1989 ), Guinea (Vervoort 1959) and Ghana ( Buchanan 1957 ; Vervoort 1959). Its bathymetric range extends from the intertidal zone to 1200 m ( Peña Cantero & García Carrascosa 2002 ). Our material was collected from a depth of 488 m . Remarks. Although gonothecae were absent in our material, the delicate aspects of the colony, such as long, thin and straight internodes disposed in zigzag directions, well-developed primary hydranthophores and stark flared hydrothecal rim, allowed us identify it as H. tenellum .