First record of the family Maxillipiidae (Crustacea: Malacostraca: Amphipoda) from Korea, including a new species and a new record species of the genus Maxillipius

This study aims to discover and document amphipods from Korea, contributing to the clarification of Korean amphipod taxonomy. As part of this effort, a new species and a newly recorded species of the family Maxillipiidae were collected from the southern waters of Korea. The new species, Maxillipius koreanus sp. nov., is similar to M. rectitelson in having a broadly developed maxillipedal palp, a similar morphology of gnathopod 1, and an extremely elongated pereopod 6.

However, it can be distinguished from M. rectitelson by differences in the shape of the coxa and propodus of gnathopod 2, the arrangement of setae on the propodus, and the morphology of dorsal projections on pleonites. Additionally, mitochondrial cytochrome c oxidase subunit I (COI) sequences support divergence at the species level. The newly recorded species, M. rectitelson, is previously known from Madagascar, Australia, and China.

It can be compared to M. commensalis, but is clearly distinguished by the shape of gnathopod 1 and coxa 2. Both species are fully illustrated and extensively compared with related species. This study represents the first record of both the genus Maxillipius and the family Maxillipiidae in Korea.

Additionally, a key to the species of Maxillipiidae is provided.