Two new species of Bulbamphiascus (Copepoda: Harpacticoida: Diosaccidae) and a related new genus, from the Bohai Sea, China.

Bulbamphiascus plumosus sp.nov. and B. spinulosus sp. nov. are described from the Bohai Sea, China, provisionally placed in the genus Bulbamphiascus, and compared with specimens of the type species, B. imus, from near the type locality (off the Northumberland coast, U.K.). Both B. plumosus and B. spinulosus can be distinguished from B. imus by the spinulation patterns on the urosome, the form of the setae on the P5 exopod, and by the lack of sexual dimorphism on the basis of the male P2. B. plumosus can be distinguished from B. spinulosus by the lack of the ventral spinule row on the preanal somite, by the presence of a large plumose seta VI on the female caudal ramus (cf, short and smooth), by segment 4 of the female antennule being only 1.5 times longer than broad (cf. 2.5 times) and by the lack of spinules on the anterior face of the male P2 endopod (cf. pronounced spinule patches). The relationship of the two new species to others in the genus is discussed. Bulbamphiascus imus is briefly redescribed and a neotype established. The flexible spine-like structure on the male P2 endopod is described for the first time and its homology discussed. It is shown that, as presently constituted, B. imus is a complex of species, and probably is not cosmopolitan in distribution, as previously postulated. Sinamphiascus gen. nov. is established, to accommodate S. dominatus sp. nov., the most common sublittoral diosaccid in the Bohai Sea. The setation of the swimming legs identifies it as a Bulbamphiascus but the form of the P1 endopod (non-prehensile, segments almost equal in length), the antennule, the antenna, the female genital field, the spinulation of the urosome and caudal ramus, and sexually dimorphic characters on the male P1 basis and P2 endopod, all suggest a closer relationship with Haloschizopera.