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

Two new species of laophontid harpacticoids are described from deep-sea hydrothermal 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 account of the complex dorsal reticulation pattern on the cephalothorax and free body somites, the distinctive sexual dimorphism on both rami of P2-P4, and the relatively pl primitive setal formula of the swimming legs. The northwest European Laophonte faroensis, currently considered as species incerta in the family (Lang, 1948), is removed from its doubtful status and transferred to Bathylaophonte. The genus Paronychocamptus is identified as a polyphyletic taxon, comprising five lineages. Under the revised concept the genus is exclusively boreal. including only two European species, P. curticaudatus and P. nanus, and two North American species, P, huntsmani and P. wilsoni. The other species P. exiguus, P. leuke, P. proprius, P. connexus and P. anomalus are reallocated to Onychocamptus Daday and three new genera. Paronychocamptus is tentatively regarded as the most likely sistergroup of Bathylaophonte. The brackish water species P. anomalus from Andhra Pradesh (India) is transferred to the genus Onychocamptus. O. besnardi from Brazil and O. vitiospinulosa from China are removed from the synonymy of O. mohammed and reinstated as valid species. The primitive position of the genus and its relationship with Folioquinpes are discussed. P. proprius from California, is placed in a new genus Psammoplatypus together with Klieonychocamptus discipes which occupied an isolated position in the genus Klieonychocamptus. Psammoplatypus is placed in the genus group comprising Coullia, Phycolaophonte, Hemilaophonte and Robustunguis. The exiguus-group of Paronychocamptus, including P. exiguus from the Chatham Islands and P. connexus ls from Tierra del Fuego, is upgraded to generic level as Heteronychocamptus gen. nov. It is considered as most closely related 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 described by Griga (1963) as Laophonte brevifurca. Both species (the latter renamed 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 Bathylaophonte gen. nov. The radiation of the family Laophontidae into deepwater habitats is reviewed. Re-examination of previous reports of 8-segmented antennules in female Laophontidae has proven these to be incorrect.