DEEP-SEA NEMATODES (NEMATA, PROCHAETOSOMATINAE) - NEW TAXA FROM HYDROTHERMAL VENTS AND A POLYMETALLIC NODULE FORMATION OF THE PACIFIC (EASTRISE NORTH FIJI AND LAU BASINS CLARION-CLIPPERTON FRACTURE-ZONE)

Dinetia nycterobia gen, et sp. n. (Draconematidae, Prochaetosomatinae) is described from a hydrothermal site of the East Pacific Rise. The n ew genus is characterized by body annulation reaching lip region and i ncluding spiral amphids, cuticle not thickened in head region, cephali c adhesion tubes without expanded base located in cervical region, pha rynx with terminal bulb provided with a thick cuticularized lumen wall , and posterior adhesion tubes with bell-shaped end. Dinetia nycterobi a, the type species, is characterized by the number of cephalic adhesi on tubes (19 in male, 15 in female) and of the 4 rows of posterior adh esion tubes (5 tubes lateral, 14-19 subventral in male, 10-15 lateral, 13-20 subventral in female) and the shape and size of the spicules. C ephalochaetosoma pacificum notium subsp. n. from the Fiji deep-sea clo sely resemble C. pacificum pacificum from Philippines deep-sea but dif fers in male by the number of sublateral posterior adhesion tubes, the shape and size of the spicules, the number of cloacal setae, the stru cture of the testis and in both sexes by the spiny cuticular ornamenta tion, the shorter labial setae and morphometric data. A new genus and new species of Draconematidae is provisionally described, based on the observation of juvenile specimens from the polymetallic nodule format ion.