The taxonomy and zoogeography of the genus Ophiocten (Echinodermata: Ophiuroidea) in the North Atlantic Ocean Gordon L. J. Paterson Department of Zoology, British Museum (Natural History), London SW7 5BD Paul A. Tyler Department of Oceanography, University College of Swansea, Swansea SA2 8PP John D. Gage Dunstaffnage Marine Research Laboratory, Scottish Marine Biological Association, P.O. Box 3, Oban, Argyll PA34 4 AD Introduction Since the late nineteenth century a large number of samples containing species of the genus Ophiocten have been recovered by many expeditions to the North Atlantic Ocean. These were described by various authors under several names. Mortensen (1927), attempting the first revision of the North Atlantic Ophiocten species, recognised four species in British waters: O. sericeum (Forbes), O. scutatum Koehler, O. latens Koehler and O. hastatum Lyman. Subsequently Mortensen (1933<z) tried to clarify the confusion surrounding Ophiocten sericeum by referring Ophioglypha signata Verrill, 1882, Ophioglypha gracilis G. O. Sars, 1871, Ophiocten le danteci Koehler, 1897, Ophiocten amitinum var. boreale Hertz, 1927, and Ophiocten abyssicolum (Forbes, 1843), to the synonymy of O. sericeum. He recog-nised two varieties of O. sericeum, one in the 'warm water' area and one in the 'cold water' area of the North Atlantic Ocean. Semenova, Mileikovsky and Nesis (1964) treated these varieties as subspecies; Ophiocten sericeum gracilis (G. O. Sars) from the warm water region and O. sericeum sericeum (Forbes), the cold water subspecies. The Scottish Marine Biological Association's deep sea sampling programme has collected many specimens of Ophiocten from bathyal depths on the Wyville Thomson Ridge, within the Rockall Trough and along the continental slope to the south west of Ireland. Close examination of these samples has thrown light on the controversy surrounding the taxonomy of Ophiocten sericeum. The present study also examines the affinities between the abyssal Ophiocten hastatum Lyman and the other deep water species outside the Atlantic Ocean, and a new abyssal species from the Bay of Biscay is described. Systematic description Genus OPHIOCTEN Liitken, 1855 Ophiocten: Lutken, 1855:97; 1858:51-52; Lyman, 1865:53; Ljungman, 1865:360; 1867:307; Lyman, 1882 : 78; Bell, 1892 : 1 13; Clark, 1915 : 328; Matsumoto, 1915. Ophiura (pt): Guille, in press. TYPE SPECIES. Ophiocten kroyeri Lutken, 1855, by monotypy, later considered by Ljungman (1865) to be conspecific with Ophiura sericea Forbes, 1852 which he referred to Ophiocten. A genus of the subfamily Ophiurinae, family Ophiuridae, with a flat disk covered with small plates amongst which the primary plates are usually distinct; margin of the disk generally Bull. Br. Mus. nat. Hist. (Zool.) 43 (3) : 109-128 Issued 30 September 1982
BioStor
