Two Species of Paracalliopiidae from the Ryukyu Archipelago in Japan, with the Description of a New Species (Crustacea: Amphipoda)

Abstract

Two species of the paracalliopiid Amphipoda are recorded from the Ryukyu Archipelago in Japan, one of which is Mucrocalliope ryukyuensis sp. nov., the second species of the genus. This new species is very similar to the type species, M. shimantoensis Ariyama and Azuma, 2011 from the Shimanto estuary, western Japan; however, M. ryukyuensis can be distinguished from M. shimantoensis by the longer peduncular article 4 of the male antenna 2 and the basis of the male pereopod 5 with a posteromedial plumose seta. The other species is Paracalliope dichotomus Morino, 1991; its morphology in female and the coloration are firstly described.