Three new species of free-living marine nematodes (Nematoda: Enoplida) from the clarion-Clipperton Fracture Zone (CCFZ), North Pacific

Three new species of free-living marine nematodes, Phanodermopsis dordi sp. nov., Halalaimus shinkai sp. nov., and Oxystomina hakureiae sp. nov. are described from the abyssal sediments of the Clarion-Clipperton Fracture Zone, North Pacific. Phanodermopsis dordi sp. nov. differs from the congeners by having papilliform anterior sensilla and a long conical tail with an acute tip. Halalaimus shinkai sp. nov., belonging to Keppner's group 2 based on the presence of caudal alae and the absence of precloacal sensillum or pore, can be distinguished from all of the members of this group by the presence of lateral pieces of gubernacula. Oxystomina hakureiae sp. nov. differs from the congeners by the short setiform anterior sensilla, the amphid located posterior to cephalic sensilla, the conico-cylindrical tail in both sexes, the spicules with a velum and a capitulum, the presence of the gubernacula and the precloacal setae, and the diorchic and monodelphic reproductive systems. The amended dichotomous keys to the species of Phanodermopsis, Halalaimus group 2, and Oxystomina are provided. A new combination Nemanema arenaria (Bussau, 1990) comb. nov. transferred from Oxystomina is also provided.