APHOTOPONTIUS-ACANTHINUS, NEW SPECIES (COPEPODA, SIPHONOSTOMATOIDA), FROM DEEP-SEA HYDROTHERMAL VENTS ON THE EAST PACIFIC RISE

A new species of siphonostomatoid, Aphotopontius acanthinus, is described from deep-sea vents at the East Pacific Rise. Although close to Aphotopontius mammillatus Humes, 1987, the female of A. acanthinus is distinguished by the genital double-somite being wider than long, not indented laterally, and possessing a pair of anterior lateral spiniform processes; the male by the elongated extension on the fifth segment of the antennule having a tripartite tip plus a spiniform seta and a much smaller seta. It is hypothesized that the large population of Aphotopontius acanthinus is sustained by the high production of chemosynthetic bacteria at the vents. Video photographs show the copepod living on the carapaces of brachyuran crabs, on limpets, and on bacteria-covered inorganic and organic surfaces.