Halecium sp.

Calder, Dale R. & Faucci, Anuschka, 2021, Shallow water hydroids (Cnidaria, Hydrozoa) from the 2002 NOWRAMP cruise to the Northwestern Hawaiian Islands, Zootaxa 5085 (1), pp. 1-73 : 21-22

Halecium sp.

Fig. 6a, b

Voucher material. Pearl & Hermes Atoll , on calcareous rubble, 28.ix.2002, two colonies or colony fragments, to 4 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5421 .— Nihoa, on calcareous rubble, 06.x.2002, one colony, 9 mm high, without gonothecae, coll. A. Faucci, ROMIZ B5422 .

Remarks. In overall colony form, hydroids examined here resemble those identified as Halecium sp. 2 from Fiji by Gibbons & Ryland (1989). Their colonies, collected from both the Suva barrier reef and the Great Astrolabe reef, were rarely more than 5 mm high. Ours were also small, attaining a maximum height of 9 mm. Likewise of similar morphology are hydroids identified as Halecium lankesterii ( Bourne, 1890) from locations including the tropical west coast of Africa ( Vervoort 1959) and South Africa ( Millard 1975). However, hydranths of that species may contain zooxanthellae ( Schuchert 2005), unlike those examined here. Moreover, that species, originally described from Plymouth, UK, seems unlikely to occur in the tropical central Pacific. Another allied species is H. plicatum Galea , in Galea & Ferry, 2015 from Martinique in the Caribbean Sea. Unlike in that species, no internal pegs of perisarc were present in the hydrorhiza. Nemalecium lighti ( Hargitt, 1924) , common in Hawaii, was discounted as a possibility because both nematodactyls and large pseudostenotele nematocysts were absent. Given the absence of gonophores, and especially those of the female, these hydroids could not be positively identified.

Reported Distribution. Hawaiian archipelago. First record.

Elsewhere.? Fiji ( Gibbons & Ryland 1989, as Halecium sp. 2 ).

Genus Nemalecium Bouillon, 1986

Figures

FIGURE 6. Haleciidae. a, Halecium sp., part of colony with two hydrothecae, Pearl & Hermes Atoll, ROMIZ B5421. Scale equals 0.1 mm. b, Halecium sp., part of colony with five hydrothecae, Pearl & Hermes Atoll, ROMIZ B5421. Scale equals 0.1 mm. c, Nemalecium lighti (Hargitt, 1924), part of hydrocaulus, with four hydrothecae, Kure Atoll, ROMIZ B5424. Scale equals 0.1 mm.