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 primitive setal formula of the swimming legs. The northwest European Laophonte faroensis T. Scott, currently considered as species incerta in the family (Lang, 1948), is removed from its doubtful status and transferred to Bathylaophonte. The genus Paronychocamptus Lang 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 (Boeck) and P. nanus (Sars), and two North American species, P. huntsmani (Willey) and P. wilsoni Coull. The other species P. exiguus (Sars), P. leuke Por, P. proprius Lang, P. connexus Pallares and P. anomalus Ranga Reddy are reallocated to Onychocamptus Daday and three new genera. Paronychocamptu 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 Jakobi from Brazil and O. vitiospinulosa (Shen & Tai) from China are removed from the synonymy of O. mohammed (Blanchard & Richard) and reinstated as valid species. The primitive position of the genus and its relationship with Folioquinpes Fiers & Rutledge are discussed.. P. proprius from California, is placed in a new genus Psammoplatypus together with Klieonychocamptus discipes Noodt which occupied an isolated position in the genus Klieonychocamptus Noodt. Psammoplatypus is placed in the genus group comprising Coullia Hamond, Phycolaophonte Pallares, Hemilaophonte Jakubisiak and Robustunguis Fiers. The exiguus-group of Paronychocamptus, including P. exiguus from the Chatham Islands and P. connexus from Tierra del Fuego, is upgraded to generic level as Heteronychocamptus gen. nov. It is considered as most closely related to Pilifera Noodt, Pseudonychocamptus Lang and Weddellaophonte Willen 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 Sars. 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 Philippi.. 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.