Bathylaophonte gen. nov from deep-sea hydrothermal vents and the polyphylyof Paronychocamptus (Copepoda : Harpacticoida)

Two new species of laophontid harpacticoids are described from deep-sea hyd rothermal vents near the Azores in the Atlantic and north of Easter Island in the Pacific. Both species are placed in a new genus Bathylaophonte on ac count of the complex dorsal reticulation pattern on the cephalothorax and f ree body somites, the distinctive sexual dimorphism on both rami of P2-P4, and the relatively pl primitive setal formula of the swimming legs. The nor thwest European Laophonte faroensis, currently considered as species incert a in the family (Lang, 1948), is removed from its doubtful status and trans ferred to Bathylaophonte. The genus Paronychocamptus is identified as a polyphyletic taxon, comprisin g five lineages. Under the revised concept the genus is exclusively boreal. including only two European species, P. curticaudatus and P. nanus, and tw o North American species, P, huntsmani and P. wilsoni. The other species P. exiguus, P. leuke, P. proprius, P. connexus and P. anomalus are reallocate d to Onychocamptus Daday and three new genera. Paronychocamptus is tentativ ely regarded as the most likely sistergroup of Bathylaophonte. The brackish water species P. anomalus from Andhra Pradesh (India) is trans ferred to the genus Onychocamptus. O. besnardi from Brazil and O. vitiospin ulosa from China are removed from the synonymy of O. mohammed and reinstate d as valid species. The primitive position of the genus and its relationshi p with Folioquinpes are discussed. P. proprius from California, is placed in a new genus Psammoplatypus togeth er with Klieonychocamptus discipes which occupied an isolated position in t he genus Klieonychocamptus. Psammoplatypus is placed in the genus group com prising Coullia, Phycolaophonte, Hemilaophonte and Robustunguis. The exiguus-group of Paronychocamptus, including P. exiguus from the Chatha m Islands and P. connexus ls from Tierra del Fuego, is upgraded to generic level as Heteronychocamptus gen. nov. It is considered as most closely rela ted to Pilifera, Pseudonychocamptus and Weddellaophonte on the basis of the sexually dimorphic setation of P3-P4 enp-1. There is an undeniable relationship between P. leuke and the species descri bed by Griga (1963) as Laophonte brevifurca. Both species (the latter renam ed P. grigae sp. nov.) are placed in a new genus Pontophonte which is most closely related to the newly defined nordgaardi-group of Laophonte. Species keys are given for Paronychocamptus, Onychocamptus and Bathylaophon te gen. nov. The radiation of the family Laophontidae into deepwater habita ts is reviewed. Re-examination of previous reports of 8-segmented antennule s in female Laophontidae has proven these to be incorrect.