Copepods (Siphonostomatoida) from a deep-sea hydrothermal vent at the Mariana Back-Arc Basin in the Pacific, including a new genus and species

Abstract

Three siphonostomatoid copepods belonging to the family Dirivultidae were found in washings of tubes of a paralvinellid polychaete, Paralvinella hessleri Desbruyères and Laubier, found in a depth of approximately 3,600 m at the Marine Back-Arc Basin (18°12·6′N, 144°42·4′E and 18°12·8′N, 144°42·4′E). Chasmatopontius thescalus gen. nov., sp. nov., differs primarily from other dirivultids in the urosome being 4-segmented in the female and 5-segmented in the male, in the inner seta on the coxa of leg 1 being enlarged, and the endopod of leg 4 being armed as 0–0; 0–3. Stygiopontius stabilitus sp. nov. resembles in many ways S. mucroniferus Humes, 1987, but differs notably in its much smaller size. Stygiopontius pectinatus Humes, 1987, previously known only from the Mid-Atlantic Ridge, occurred at the same site.