Halecium beanii (Johnston, 1838)

Gil, Marta & Ramil, Fran, 2025, Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau, Zootaxa 5577 (1), pp. 1-89 : 38

Halecium beanii (Johnston, 1838)

( Fig. 6D–E )

Thoa beanii Johnston, 1838: 120–121 , pl. 7 figs 1–2.

Halecium beanii : Ralph, 1958: 332–334, fig. 10a, b, e–k.—Millard, 1975: 144–145, fig. 47A–E.— Cornelius, 1995a: 276–278, fig. 62.— Ramil et al., 1998: 7.— Medel & Vervoort, 2000: 8–12, fig. 1.— Schuchert, 2005: 615–618 , figs 5, 6.

Material examined. BISSAU-0810, stn BS152, 10º31'12"– 10º30'19"N, 17º12'34"– 17º12'32"W, 300–305 m, 27-X-2008: one colony with female gonothecae, growing on Lytocarpia myriophyllum .

BISSAU-0810, stn BS191, 10º18'25"– 10º19'20"N, 16º08'47"– 16º08'47"W, 24–25 m, 3-XI-2008: one colony with female gonothecae; substrate unknown.

BISSAU-0810, stn BS216, 10º30'53"– 10º31'39"N, 16º31'33"– 16º32'02"W, 56–58 m, 7-XI-2008: 20 colonies (six with male gonothecae, seven with female gonothecae), 35–255 mm high, of which one growing on a polychaete tube.

Remarks. In the material studied here, some colonies from the station BS216 were found growing on other colonies of H. beanii . This phenomenon was described by Millard (1973) as auto-epizoism, and was documented in some plumulariid and lafoeid hydroids.

Biology. This species has been found growing on algae, rocks, concretions, barnacles, echinoderms, hydroids and the coral D. pertusum ( Gravili et al. 2015; Gil et al. 2020). In the northern hemisphere, gonothecae have been observed throughout the year ( Cornelius 1975; Gil & Ramil 2017a), while in the southern hemisphere, fertile material was observed in January, February, May and October ( Ralph, 1958; Schuchert 2005).

In our material, colonies were found growing on L. myriophyllum and a polychaete tube. Gonothecae were observed in October and November.

Distribution. Halecium beanii is a circumglobal species ( Medel & Vervoort 2000; Gil et al. 2020). Its distribution in West Africa has been recently revised by Gil et al. (2020). This species has a wide bathymetric distribution, ranging from 0 to 1134 m depth ( Millard 1978).

Our material was collected at depths between 24–305 m.

Figures

FIGURE 6. A–C. Obelia pseudodichotoma (Vervoort, 1959) (stn SL-20): portion of colony with hydrotheca and gonotheca (A); (stn BS191), portion of colony with hydrothecae and gonothecae (B); (stn SL-13), gonotheca with medusa bud (C). D–E. Halecium beanii (Johnston, 1838) (stn BS216); portion of colony with female gonotheca (D); male gonotheca (E). Scales: a–e, 0.5 mm.