Halecium tenellum Hincks, 1861

Gil, Marta & Ramil, Fran, 2025, Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau, Zootaxa 5577 (1), pp. 1-89 : 43-44

Halecium tenellum Hincks, 1861

Halecium tenellum Hincks, 1861: 252 , pl. 6 figs 1–4.— Cornelius, 1975: 409–411, fig. 12.— Ramil & Vervoort, 1992a: 90–91, fig. 21F–G.— Cornelius, 1995a: 296–297, fig. 69.— Migotto, 1996: 34–35, fig. 6H.— Peña Cantero & García Carrascosa, 2002: 75–77, fig. 12C–E.— Vervoort, 2006: 254

Material examined. BISSAU-0810, stn BS191, 10º18'25"– 10º19'20"N, 16º08'47"– 16º08'47"W, 24–25 m, 3-XI-2008: six colonies without gonothecae, of which three growing on bryozoans and one on a bivalve.

BISSAU-0810, stn BS192, 10º19'30"– 10º20'15"N, 16º10'27"– 16º10'59"W, 24 m, 3-XI-2008: 12 colonies without gonothecae, 6–7 mm high, of which eight growing on Idiellana pristis and one on Tridentata loculosa .

BISSAU-0810, stn BS194, 10º21'59"– 10º22'36"N, 16º13'23"– 16º14'03"W, 21–24 m, 3-XI-2008: three colonies without gonothecae, of which two growing on bryozoans and one on Idiellana pristis .

BISSAU-0810, stn BS195, 10º22'44"– 10º23'22"N, 16º15'37"– 16º16'18"W, 29 m, 3-XI-2008: three colonies without gonothecae, all growing on bryozoans.

Remarks. Halecium tenellum is a well-known and widespread species. No further discussion is needed.

Biology. This species has been found growing on rocks, algae and a wide range of invertebrates such as hydrozoans, bryozoans, polychaete tubes, anthozoans, sponges and D. pertusum ( Peña Cantero & García Carrascosa 2002; Gil et al. 2020). In the northern hemisphere, fertile material has been found in January, April–June, October and December ( Medel & Vervoort 2000; Peña Cantero & García Carrascosa 2002), while in the southern hemisphere, gonothecae were observed in April and May ( Migotto 1996).

The colonies studied by us were found growing on I. pristis , T. loculosa , bryozoans and bivalves. Gonothecae were not observed.

Distribution. Halecium tenellum is a cosmopolitan species ( Cornelius 1975), with some erroneous records from high latitudes of the North Atlantic ( Calder 1991; Schuchert 2005). In West Africa, it has been recorded from Morocco ( Patriti 1970; Ramil & Vervoort 1992a) to Ghana ( Buchanan 1957; Vervoort 1959), including the Valdivia Seamount ( Gil & Ramil 2021b). Its bathymetric distribution ranges from the intertidal zone to 1200 m ( Peña Cantero & García Carrascosa 2002).

Our material was collected at depths between 21–29 m.