Pseudorchomene boreoplebs, a new lysianassid amphipod from Korean waters (Crustacea, Amphipoda, Lysianassoidea)

Until now, the genus Pseudorchomene Schellenberg, 1926 has been recorded exclusively in Antarctic or sub-Antarctic regions. Pseudorchomene boreoplebs sp. n., described from Korean waters, is the first record from the Northern Hemisphere as well as from temperate regions. This new species is very similar to Pseudorchomene plebs (Hurley, 1965), but can be readily distinguished by its wider basis of gnathopod 1, elongate carpus and angulate anterodistal corner of the propodus on gnathopod 2, having slender setae only on the posterior margin of the carpus on pereopod 5, and lacking posterior lobations of the carpus on pereopods 5–7.