Deep-sea Rhachotropis (Crustacea: Amphipoda: Eusiridae) from New Zealand and the Ross Sea with key to the Pacific, Indian Ocean and Antarctic species

摘要

The amphipod genus Rhachotropis has a worldwide distribution. Four species new to science are described, increasing the total number of Rhachotropis species to 59. Only one species was previously known from New Zealand and none from the Ross Sea. Twospecies Rhachotropis chathamensis sp. nov. and R. delicata sp. nov. were collected at the same station in 420 m depth off eastern New Zealand; R. rossi sp. nov. and R. abyssalis sp. nov. were collected below 3000 m depth in the Ross Sea, Antarctica. Investigation of,recently collected material as well as historic material from the NIWA Invertebrate collection revealed several specimens of Rhachotropis antarctica K.H. Barnard, 1932 sampled in the Ross Sea. Four damaged Rhachotropis specimens, recently collected from 5170 m in the Kermadec Trench, north of New Zealand, are reported. Epibionts have been discovered on the mouthparts of several specimens from New Zealand as well as the Ross Sea. Preliminary molecular investigations of the phylogeney of Rhachotropis are briefly discussed. A key to Pacific, Indian Ocean and Antarctic species of Rhachotropis is provided.