New Nicothoid copepods (Copepoda: Siphonostomatoida) from an amphipod and from deep-sea isopods Geoffrey A. Boxshall & Keith Harrison Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Summary One new genus, Cephalorhiza, and eight new species of parasitic copepods of the family Nicothoidae are described. One new species, Sphaeronella australis, is parasitic in the brood pouch of a lyssianasoid amphipod from southern Australia. All the other new taxa are parasites of deep-sea asellote isopods, from the North Atlantic and Indian Oceans. Two new species belong to the genus Rhizorhina, 4 belong to Diexanthema and one, Cephalorhiza flaccida, to the new genus. Introduction The family Nicothoidae contains eighteen genera of small, highly transformed copepods, all of which are parasitic on other crustaceans. Several of these genera are known either from amphi-pods (Stenothocheres Hansen) or from isopods (Diexanthema Ritchie, Choniorhiza Boxshall & Lincoln, Nicorhiza Lincoln & Boxshall), or from both amphipods and isopods (Rhizorhina Hansen, Sphaeronella Salensky). The present account describes a new species of Sphaeronella found in the marsupium of an amphipod from Australia and several new taxa from deep-sea asellote isopods collected in the North Atlantic and Indian Oceans. During an ecological study of the asellotes of the Rockall Trough, off the west coast of Scotland, about 15,500 asellote isopods were examined. Only four specimens harboured nicothoid parasites, which were found to represent four new species. Examination of additional material from the Porcupine Seabight and from the collections of the Centre National de Tri d'Oceanographie Biologique (CENTOB, Brest) made off the island of Reunion in the Indian Ocean, revealed another three new species, one belonging in a new genus. Descriptions Family NICOTHOIDAE Rhizorhina hystrix sp. n. POSTMETAMORPHOSIS FEMALE. Body highly transformed, simplified to a globular, almost spherical, trunk portion (Fig. IB) and an intricate branching holdfast (Fig. 1 A). Maximum width of globular trunk 859 urn, maximum length 788 um; trunk featureless except for raised gonopores located about 353 um apart on posterior surface. Small anterior swelling tapers towards branching holdfast. Holdfast 4-branched at origin, processes branching irregularly along length. Maximum extent of holdfast within host about 680 um from origin. Arrangement of holdfast branches more or less 2-dimensional within host. MATERIAL EXAMINED. Holotype ?, parasitic on a preparatory female of Eurycope complanata Bonnier (sensu Wilson, 1982). Locality: Discovery Stn 50602 # 2 in the Porcupine Seabight (511-0'N 137-2'W), depth 1955-1980 m, 07.vii.1979. Parasite located on arthrodial membrane between tergites of pereon segments 3 and 4. Holotype stored in BM(NH), Reg. No. 1987.435. Bull. Br. Mus. nat. Hist. (Zool.) 54(6): 285 299 Issued 24 November 1988
BioStor
