Halecium halecinum ( Linnaeus, 1758 )

Halecium halecinum ( Linnaeus, 1758) View in CoL

( Fig. 7A View FIGURE 7 )

Sertularia halecina Linnaeus, 1758: 809 View Cited Treatment .

Halecium halecinum View in CoL : Vervoort, 1959: 225–226.— Patriti, 1970: 22–23, fig. 19.—Millard, 1975: 150–151, fig. 49A–E.— Cornelius, 1995a: 279–281, fig. 63.— Medel & Vervoort, 2000: 14–18, fig. 2.— Schuchert, 2005: 612–615 View Cited Treatment , figs 3, 4.— Vervoort, 2006: 252.

Material examined. BISSAU-0810, stn BS147, 11º08'35"– 11º08'27"N, 17º11'31"– 17º10'37"W, 186–306 m, 26-X-2008: five colonies (one with male gonothecae), 66–235 mm high, of which one growing on a worm tube.

BISSAU-0810, stn BS193, 10º21'13"– 10º21'51"N, 16º10'17"– 16º10'56"W, 20–21 m, 3-XI-2008: two colonies without gonothecae, up to 8 mm high, both growing on bryozoans.

BISSAU-0810, stn BS216, 10º30'53"– 10º31'39"N, 16º31'33"– 16º32'02"W, 56–58 m, 7-XI-2008: two colonies, 41–54 mm high, without gonothecae; substrate unknown.

BISSAU-0810, stn BS226, 11º22'11"– 11º21'55"N, 17º02'30"– 17º01'54"W, 35–37 m, 9-XI-2008: three colonies up to 28 mm high, without gonothecae, of which two growing on Sertularelloides cylindritheca .

CCLME-1110, stn BT49, 10º57'13"– 10º58'26"N, 16º59'29"– 17º00'29"W, 62 m, 29-X-2011: one colony without gonothecae growing on a polychaete tube.

Remarks. The identification of this material as H. halecinum is considered tentative because none of the colonies examined had female gonothecae. Nevertheless, their morphology is consistent with that described for this species by Cornelius (1995a) and Schuchert (2005), and at the same time different from the material with female gonothecae, which is undoubtedly identified as H. beanii in this report.

Some of the colonies showed ‘extensible polyps’, similar to those described by Gravier-Bonnet (2008) in her study of the polymorphism in hydroids, whose functions are probably defensive, excretory and perhaps sensory. Our material represents the first record of this species for Guinea-Bissau.

Biology. This species has been reported colonizing a great variety of substrates, such as bryozoans, sponges, polychaete tubes, bivalves, stones and other hydroids ( Cornelius 1995a; Medel & Vervoort 2000). In the northern hemisphere, fertile material has been collected from April to July, September, November and December ( Cornelius 1975; Medel & Vervoort 2000; Schuchert 2005; Gil & Ramil 2017a), while in the southern hemisphere, gonothecae were observed in July ( Millard 1966a).

In our material, some colonies were found growing on worm tubes, bryozoans and the hydroid S. cylindritheca . One colony with gonothecae was found in October.

Distribution. Halecium halecinum is an almost cosmopolitan species ( Medel & Vervoort 2000; Schuchert 2005), but it was not included among the hydroid fauna of the Southern Ocean ( Peña Cantero 2004). In West Africa, it has been recorded from Morocco ( Patriti 1970; Medel & Vervoort 2000), Mauritania ( Medel & Vervoort 2000; Gil & Ramil 2017a), the Cape Verde Islands ( Medel & Vervoort 2000), Senegal, Gambia ( Vervoort 1959) and the Ivory Coast ( Redier 1965, 1971). Its bathymetric distribution extends from the littoral zone down to 1387 m ( Boero & Fresi 1986; Gil & Ramil 2017a).

Our material was collected at depths between 20–306 m.