THE DEEP-WATER PYCNOGONIDS (ARTHROPODA, PYCNOGONIDA) OF THE NORTHEASTERN ATLANTIC-OCEAN

Over 2000 specimens of pycnogonid from deep-sea collections made in th e northeastern Atlantic Ocean by IOS and SMBA between 1971 and 1994 ha ve been analysed. Thirty-five species were identified, two being new t o science, viz Nymphon akanthockoeros and an unnamed Anoplodactylus sp ecies. The deep-sea Pycnogonida of the northeastern Atlantic are revie wed using these data and records from the literature. Keys are present ed for the six families represented by more than one species. The pycn ogonid fauna of this area is characterized particularly by Paranymphon spinosum and Colossendeis clavata, with other dominant species includ ing Colossendeis species, notably C. macerrima and Nymphon laterospinu m, Anoplodactylus typhlops and A. arnaudae. Of the 54 species recorded below 200 m in the northeastern Atlantic, available evidence suggests that nine are 'endemic'. Relative distributions of the other species are discussed. A distinct change in the pycnogonid fauna with depth wa s found at around 1400 m. There is latitudinal separation of species g roupings, shown most conspicuously by the shallower water species. (C) 1995 The Linnean Society of London