New Aegisthidae (Copepoda : Harpacticoida) from western Pacific cold seepsand hydrothermal vents

Hyperbenthic harpacticoid samples from Japanese hydrothermal vents in the O kinawa Trough and cold seep sites in Sagami Bay were examined and resulted in the discovery of four new species belonging to three new genera of Aegis thidae (Copepoda: Harpaeticoida). Females of Nudivorax todai gen. et sp. no v. possess a large area of flexible integument between the cephalosome and the first pedigerous somite which is suggestive of a gorging feeding strate gy. Main diagnostic characters separating the new genus from other. Aegisth idae are provided by the unusually short caudal rami, the complete lack of integumental surface lamellae, and the presence in the male of a linear arr ay of pores along the rostral margin which appears to be sensory in functio n. Scabrantenna yooi gen. et sp. nov. displays several similarities with Ae gisthus aculeatus Giesbrecht, 1891 but is highly distinctive in its male mo rphology which includes extremely atrophied mouthparts and a unique prehens ile antenna. Jamstecia terazakii gen. et sp. nov. is only known from a sing le female caught in the Okinawa Trough. Jamstecia gen. nov. is most closely related to Andromastax Conroy-Dalton & Huys, 1999 but can be distinguished on the basis of the elongate antennules, the antennary morphology, the abs ence of lateral spinous processes on the cephalosome and swimming legs 2-4, and differences in the mandibular palp and armature of the maxilliped. And romastax cephaloceratus sp. nov. differs from the type species A. muricatus Conroy-Dalton & Huys, 1998 primarily in the absence of long spinous proces ses on the cephalosome and the absence of the inner seta on the female P5. (C) 2000 The Linnean Society of London.