A new deep-sea genus and species of the family Ecbathyriontidae (Copepoda: Siphonostomatoida) from the Gorda Ridge (North Pacific Ocean)

Adult females of Bathygordion cliffus new gen. and new sp. belonging to the family Ecbathyriontidae Humes, 1987 are described from the Gorda Ridge of the North Pacific Ocean. The copepods were found at depth of 2701 m on the margin of a hydrothermal vent field (Sea Cliff, GR-14) among invertebrates colonizing wood blocks deployed for 2 years. The new genus differs from the only monotypic genus Ecbathyrion Humes, 1987 reported from hydrothermal vents of the Galapagos Rift and the East Pacific Rise in a number of morphological features (such as three articulating abdominal somites, mandible with 1 palp bearing setae, base of leg 1 with inner seta, distal exopodal segment of leg 4 with four inner setae, leg 5 2-segmented), suggesting long evolutionary history of the deep-sea family endemic to hydrothermal vents of the East Pacific. The derived feature of the new genus is the presence of one terminal spine on the distal endopodal segment of leg 3 (instead of bearing two terminal setae in Ecbathyrion). The diagnosis of the family Ecbathyriontidae is emended.