First record of the family Calliopiidae (Crustacea, Malacostraca, Amphipoda) from Korean waters, with description of new species Calliopiusulleungensis sp. nov

A new species of the family Calliopiidae was collected from the East Sea of Korea. Calliopiusulleungensis sp. nov. is similar to C.columbianus Bousfield & Hendrycks, 1997 in having numerous calceoli on the posteromedial margins of antennae and a weakly carinate body. However, the new species can be distinguished from C.columbianus by the shorter process on peduncular article 3 of antenna 1, subrectangular eyes, and fewer articles in the antenna flagellum. This species, along with C.ezoensisShimoji et al. 2020, occurs in the Western Pacific. The females of the two species are morphologically very similar, but the males of C.ezoensis are easily distinguishable, as the gnathopod 1 is larger than gnathopod 2. The new species is fully illustrated and extensively compared with related species. In this paper, both Calliopius and Calliopiidae are reported from Korea for the first time. A key to species of Calliopius is also provided.