A new species of from Japan (Crustacea, Amphipoda, Melitidae).

A new brackish-water species of melitid amphipod, , from the Choshigawa River, Mie Prefecture, Japan, is named and described. is distinguished from the most similar (Uéno, 1940) by having an elongate and weakly arched male uropod 3, and a deep and strongly hooked anterior lobe of the coxa on the female's pereopod 6. Nucleotide sequences of the mitochondrial cytochrome oxidase subunit I (COI) of and support divergence at the species level.

DNA markers indicate low genetic diversity and high genetic divergence in the landlocked freshwater goby, Rhinogobius sp. YB, in the Ryukyu Archipelago, Japan.

Genetic diversity and genetic divergence were investigated in the landlocked goby Rhinogobius sp. YB by analysis of seven microsatellite DNA loci and the mtDNA control region sequence, and were compared with those of the closely related amphidromous species Rhinogobius sp. DA.