Halopteris diaphana ( Heller, 1868 )

Gil, Marta & Ramil, Fran, 2025, Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau, Zootaxa 5577 (1), pp. 1-89 : 63

Halopteris diaphana ( Heller, 1868)

Anisocalyx diaphanus Heller, 1868: 42 , pl. 2 fig. 5.

Halopteris diaphana : Schuchert, 1997: 47–52, fig. 15.— Ansín Agís et al., 2001: 163–167, fig. 69.— Gil & Ramil, 2021a: 179, fig. 5C.

Material examined. BISSAU-0810, stn BS191, 10º18'25"– 10º19'20"N, 16º08'47"– 16º08'47"W, 24–25 m, 3-XI-2008: eight colonies without gonothecae, 5 mm high, of which two growing on bryozoans and one on Diphasia digitalis .

Remarks. Halopteris diaphana is similar to H. alternata ( Nutting, 1900) , a species recorded by Ansín Agís et al. (2001) from Madeira, Canary and the Cape Verde Islands. Both species can be easily separated based on the morphology of the female gonothecae and additional differences highlighted by Ansín Agís et al. (2001).

Our material, characterized by the heteromerous segmentation of the hydrocaulus, the absence of axillary nematothecae behind the cauline hydrothecae and the presence of two nematothecae on the ahydrothecate cauline internodes, corresponds to H. diaphana .

Our colonies represent the first record of this species for Guinea-Bissau.

Biology. This species has been found growing on D. digitalis ( Gil & Ramil 2021a) . Colonies with gonothecae have been found in the northern hemisphere in April, June, July and September ( Schuchert 1997; Ansín Agís et al. 2001), while in the southern hemisphere gonothecae have been found only in November ( Schuchert 1997).

In our material, some colonies were also found growing on D. digitalis and bryozoans. Gonothecae were not observed.

Distribution. Halopteris diaphana is a circumtropical species whose distribution in West Africa, has been recently revised by Gil & Ramil (2021a). Its bathymetrical distribution ranges from 0 to 240 m ( Ansín Agís et al. 2001).

Our material was collected at depths between 24–25 m.

Genus Polyplumaria G.O. Sars, 1874