New genera and species of the Synchelidium group (Amphipoda: Oedicerotidae) from Asia-North Pacific.

Four new species and two new genera belonging to the family Oedicerotidae are reported from Korea and Vietnam. Two new genera, Orthomanus and Imbachoculodes are described, with three new species, namely Orthomanus koreanus gen. et sp. nov., Imbachoculodes namhaensis gen. et sp. nov. and Imbachoculodes vietnamensis gen. et sp. nov. The monotypic genus Orthomanus is characterized by the very short carpi and transverse palms of gnathopods 1 and 2, the reduced dactyli on pereopods 3–6, and the greatly enlarged distolateral spine-tooth on the outer plate of maxilla 1. Imbachoculodes has slender gnathopods 1 and 2 with elongated carpi, pereopods 3 and 4 with elongated dactyli, and a narrow basis of pereopod 7. The fourth new species, Sinoediceros hwanghaensis sp. nov. has a greatly reduced flagellum on antenna 2, a broadened meri on pereopods 3 and 4, and an elongated maxilliped outer plate. Keys are provided to 1) the North Pacific genera of the Synchelidium group, 2) species of Imbachoculodes, and 3) species of Sinoediceros. [ABSTRACT FROM PUBLISHER]