Corydendrium parasiticum ( Linnaeus, 1767 )

Calder, Dale R., 2010, Some anthoathecate hydroids and limnopolyps (Cnidaria, Hydrozoa) from the Hawaiian archipelago 2590, Zootaxa 2590 (1), pp. 1-91 : 11-13

Corydendrium parasiticum ( Linnaeus, 1767)

Fig. 3

Sertularia parasitica Linnaeus, 1767: 1315 .

Type locality. “ Habitat in Oceano …” ( Linnaeus 1767) .

Material examined. Oahu: Pearl Harbor, on boat in drydock, 5.iv.1950, three colony fragments, to 6.2 cm high, without gonophores, BPBM D308 .

Description. Hydroid colonies erect, straggly, up to 6.2 cm high, arising from a creeping, non-encrusting hydrorhiza. Hydrocaulus and main branches rather crooked, polysiphonic except at distalmost extremities, with stout individual tubes (~0.5 mm in diameter); branching irregular, mostly in one plane; branches adnate to hydrocaulus or to larger branches basally, gradually curving way from supporting stem and becoming free; distalmost branches and branchlets supporting hydranths, tending to be alternate; ultimate branchlets (pedicels) of varied length. Perisarc mostly smooth, mostly of moderate thickness, becoming thin and terminating at end of a tubular ultimate branchlet protecting hydranths, sometimes with striations or wrinkles on branchlets, not annulated, yellowish in older parts of colony, becoming almost clear in younger distal parts, occasionally with adhering silt and detritus. Hydranths clavate to almost cylindrical, about 2 mm long, constricted basally, retractable into perisarcal sheath of varying length; tentacles numerous, filiform, scattered over distal half or more of hydranth, distal ones longer and thicker than those those proximally; hypostome conical, elongate.

FIGURE 2. Corydendrium corrugatum : part of hydrocaulus of lectotype colony, with a hydranth, USNM 22150. Scale equals 0.5 mm.

FIGURE 3. Corydendrium parasiticum : part of hydrocaulus, hydranths lacking, BPBM D308. Scale equals 1 mm.

FIGURE 4. Rhizogeton sp. : hydranth, ROMIZ B3833. Scale equals 0.5 mm.

FIGURE 5. Turritopsis minor : part of hydrocaulus of lectotype colony, with hydrocladium, hydranth, and gonophores, USNM 22184. Scale equals 0.5 mm.

FIGURE 6. Turritopsis cf. nutricula : part of colony with a hydranth, ROMIZ B3298. Scale equals 0.25 mm.

FIGURE 7. Cordylophora caspia : part of hydrocaulus, with hydranths and gonophores (after Cooke 1977). Scale equals 0.5 mm.

FIGURE 8. Bimeria vestita : hydrocaulus with hydranths, ROMIZ B3821. Scale equals 0.5 mm.

FIGURE 9. Bougainvillia muscus : part of hydrocaulus with hydranths and medusa buds, ROMIZ B3823. Scale equals 0.5 mm.

FIGURE 10. Bougainvillia muscus : newly liberated medusa, ROMIZ B3823. Scale equals 0.5 mm.

Gonophores not seen.

Remarks. The biology and distribution of Corydendrium parasiticum ( Linnaeus, 1767) has been reviewed by Schuchert (2004), and its synonymy by Calder (1988), Hirohito (1988), and Schuchert (2004). The species is thought to be circumglobal in shallow tropical and subtropical waters, and is widespread in warm regions of the Pacific Ocean ( Vervoort 1941; Calder et al. 2003; Kirkendale & Calder 2003). The nematocyst complement has been described and illustrated in material from Bermuda by Calder (1988) and from Brazil by Migotto (1996). Lindquist et al. (2000) and Stachowicz & Lindquist (2000) identified bioactive secondary metabolites in C. parasiticum that acted as deterrents to potential predators.

Reported distribution. Hawaii. Oahu: Pearl Harbor, reported herein.

Worldwide. Circumglobal in warm waters; about 1–90 m ( Schuchert 2004).