A new species of the genus Elasmopus (Crustacea: Amphipoda: Maeridae), from Honshu, Japan

A new species of maerid amphipod, Elasmopus projectus sp. nov., is described from shallow subtidal zones along the temperate coast of Honshu, Japan. The new species is distinguished from its congeners by long slender setae on the posterior margin of the male gnathopod 2 propodus, a well-developed mid-palmar process on the male gnathopod 2 propodus, and a smooth posterior margin on the basis of pereopods 5–7. Additionally, the nucleotide sequence of the mitochondrial cytochrome c oxidase subunit I was determined from the holotype.

A key to the species of Elasmopus found in Japan is provided.