Admirandus multicavus and Adoncholaimus ussuriensis sp. n. (Nematoda: Enoplida: Oncholaimidae) from the Sea of Japan.

A description of one new, and redescription of one known, species of the subfamily Adoncholaiminae (Nematoda: Oncholaimidae) from Peter the Great Bay (Sea of Japan) are provided. Adoncholaimus ussuriensis sp. n. is characterised by relatively large body size (L = 4.3-5.8 mm in male, 4.4-6.2 mm in female), a pair of terminal pores of the Demanian system opening dorsally at 147-189 µm (2.3-3.0 abd) anterior to the anus, excretory pore located posterior to buccal cavity region, absence of a ventral swelling on tail, long spicules (190-230 µm), presence of a gubernaculum (32-40 µm), presence of a complicated sensory field in the male with a complex supplementary organ and two sets of pilose filaments (5-10 µm long) on the posterior cloacal lobe and four rows of subventral and subdorsal postcloacal sensilla. We provide a redescription of Admirandus multicavus illustrated by light and scanning electron micrographs and propose Adoncholaimus chinensis as a junior synonym of Admirandus multicavus. The diagnoses of both genera are emended. Partial sequences of the mitochondrial gene cytochrome oxidase c subunit I (COI) and D2-D3 region of the 28S rDNA for both species were obtained. A dichotomous key to Adoncholaimus species is provided. [ABSTRACT FROM AUTHOR]