Papers from the Echinoderm Conference. 5. A new genus and species of ophiacanthid brittlestar (Echinodermata: Ophiuroidea) from the Kerguelen Islands, with new taxonomic, biogeographic and quantitative data on the echinoderm fauna
Forty-two species have been sampled on the continental shelf of Kerguelen islands during MD04/Benthos cruise of M.S. "Marion-Dufresne" (March 1975). Among the species, the taxonomic position of a few animals is still uncertain. Four ophiuroids however, allow interesting taxonomic and biogeographical comments: a new genus and new species in the family Ophiacanthidae, Ophioparva blochi, is described; Ophiomisidium speciosum Koehler was known previously only from the tropical deep Atlantic; Ophiocten hastatum Lyman and Ophiocten amitinum Lyman are placed in the genus Ophiura. The fauna has a generally wide antarctic and sub-antarctic distribution, but a few species are endemic to the Kerguelen province. Ophiura hastata and the newly recorded Ophiomisidium speciosum are also known from the deeper parts of the sub-tropical Atlantic.
On the continental shelf, the average density of echinoderm individuals is 52.8 m2 at depths between 10 and 180 metres. In fjords, the density of individuals is high but the number of species is low. On the contrary, outside of the fjords in open sea, the density of individuals is low but the specific diversity is high. Around the Kerguelen islands, the specific and quantitative composition of the echinoderm fauna is correlated with hydrological conditions, in particular with the west wind drift.