New Hyocrinid Crinoids (Echinodermata) from Submersible Investigations in the Pacific Ocean

A few specimens belonging to the deep-sea family Hyocrinidae (stalked Crinoidea, Echinodermata) collected by submersible in the eastern and western Pacific Ocean are described. Laubierierinus pentagonalis, n. genus, n. sp., from the North Fiji Rise is the first discovery of a hyocrinid crinoid with a pentaradially symmetrical stalk. Hyocrinus biscoitoi, n. sp., from the East Pacific Rise attains large size and has close affinities with H. giganteus from Horizon Seamount. Additional information is given concerning H. foelli found near cold seeps on the Mexican continental margin; H. cyanae, previously collected on New Caledonian slopes; and Calamoerinus diomedae from the Cocos Ridge and Galapagos slopes. For the latter, the first young specimens known document ontogenetic trends in this famous species. HYOCRINIDS ARE stalked crinoids that attach to rocky substrates by their encrusting disk. They live in cold, deep water on continental margins, rises, seamounts, and ferromanganese nodule fields in abyssal plains. Ptiloerinus antareticus excepted (depth range 450-500 m), hyocrinid crinoids inhabit depths in excess of 700 m. Specimen are scarce in dredge and trawl samples, but deep-sea photographs taken via submersible have revealed several cases of abundant stalked crinoid populations including hyocrinids on rocky current-swept substrates (Roux 1980a, 1985). During the last decade our knowledge of hyocrinids has progressed rapidly. In 2002, Roux et al. listed 20 species of living Hyocrinidae, eight of which were known in 1973 (Roux 1980b) and 10 described since 1998 mostly by Mironov and Sorokina (1998). Here, I describe a few specimens including two new species and a new genus from material collected by sub1 This paper is a contribution of UMR 5561, Biogeosciences, CNRS. Manuscript accepted 19 November