Eudendrium carneum Clarke, 1882

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 40-42

Eudendrium carneum Clarke, 1882

Figs. 26, 27

Eudendrium carneum Clarke, 1882: 137 , pl. 7, figs. 10–17.

Type locality. USA: Virginia, Hampton Roads, Fort Wool ( Clarke 1882) .

Material examined. Oahu, Pearl Harbor, on boat in dry dock, 5.iv.1950, 16 colony fragments in fair to poor condition, up to 10 cm high, eight with female gonophores, five with male gonophores, three without gonophores, BPBM D307.–Oahu, Pearl Harbor, Alpha Docks, 25.vii.1976, ~ 5 m, on Schizoporella , five colony fragments, to 7 cm high, with female gonophores, coll. P.Z. Langford, BPBM (without collection number).–Oahu: Honolulu Harbor, Pier 20, 16.ix.1997, one colony, 9 cm high, with male gonophores, coll. R. DeFelice and S. Coles, BPBM D1083.

Description. Colonies erect, up to 10 cm high, arising from a hydrorhizal mat or broken off near base, straggly in form; branching in some parts occasionally regular and alternate but predominantly irregular. Hydrocaulus polysiphonic basally, monosiphonic distally; main branches long, most of them monosiphonic, typically quite straight, resembling hydrocaulus. Perisarc in older parts of colony thick, dark brown, becoming thinner and golden-coloured in younger parts, terminating at perisarc groove on base of hydranths, mostly smooth but with annulations at bases of branches and pedicels, a few annulations elsewhere on hydrocaulus, branches and pedicels. Hydranths urn-shaped, in preserved material up to about 0.6 mm long from base to hypostome, 0.3 mm wide; base ringed by perisarcal groove and band of heterotrichous anisorhizas; hypostome large, knob-shaped to flared. Tentacles solid, filiform, in one whorl, about 25 in number.

Gonophores fixed sporosacs, borne on atrophied blastostyles. Female gonophores with bifid spadix curving over egg; each spadix secreting a perisarcal capsule around embryo before being shed; clusters of embryos in perisarcal capsules scattered along ultimate branchlets; perisarc of these branchlets becoming wrinkled proximally. Male gonophores comprising a linear series of up to five chambers; each distal chamber armed with heterotrichous anisorhizas; blastostyles with as many as 10 strings of gonophores.

Nematocysts. Heterotrichous microbasic euryteles (abundant on tentacles; present on hydranths and male gonophores)

Heterotrichous anisorhizas (occurring in a ring around hydranth base; also present on hypostome and at tips of male gonophores)

Remarks. Eudendrium carneum Clarke, 1882 is widespread and well-known. Detailed accounts of its taxonomy and natural history are given by authors including Millard (1975), Watson (1985), Calder (1988), Marques, Mergner et al. (2000); Marques, Peña Cantero et al. (2000), and Schuchert (2008b), and need not be repeated here. Its occurrence in many areas has been attributed to shipping ( Watson 1985), and discovery of E. carneum in collections from the ports of Pearl Harbor and Honolulu Harbor in Hawaii accord with this hypothesis.

Although reported here for the first time from Hawaii, Eudendrium carneum has been established in waters of the state for more than 50 years based on previously unidentified material examined here (BPBM D307).

FIGURE 25. Eudendrium capillare : nematocysts, ROMIZ B3826. a–b, heterotrichous microbasic euryteles (undischarged). c, heterotrichous microbasic eurytele (discharged).

FIGURE 26. Eudendrium carneum : part of colony with hydranth and male gonophores, BPBM D1083. Scale equals 0.5 mm.

FIGURE 27. Eudendrium carneum : part of female colony with encapsulated embryos, BPBM D307. Scale equals 0.25 mm.

The cnidome of this species is as described earlier ( Calder 1988).

Reported distribution. Hawaii. New record.

Worldwide. Circumtropical; 0–137 m, but usually in the upper 20 m ( Fraser 1946; Watson 1985; Marques, Mergner et al., 2000; Marques, Peña Cantero et al. 2000; Schuchert 2008b).