A new sand-burrowing amphipod Grandifoxus donghaensis sp. nov. (Crustacea: Amphipoda: Phoxocephalidae) from the East Sea of South Korea, with population genetic structure of Haustorioides koreanus

To improve our understanding of the diversity of Korean sand-burrowing amphipods, we conducted a taxonomic assessment of an undescribed phoxocephalid species together with a population genetic analysis of the dogielinotid amphipod Haustorioides koreanus . Here, we describe a new sand-burrowing amphipod, Grandifoxus donghaensis sp. nov., from the East Sea of South Korea. This species can be distinguished from its congeners by a combination of morphological characteristics, including a long rostrum, absence of facial spine on the merus of pereopod 6, presence of a row of facial setae on urosomite 1, marginal spines on the inner ramus of uropod 2, and two dorso-lateral spines on each telson lobe. Partial gene sequences of the mitochondrial cytochrome c oxidase subunit I (COI) of the new species were determined and an identification key to the genus is provided. The COI sequences of Haustorioides koreanus populations from the Yellow Sea and the East Sea were analyzed. Comparative analysis of COI haplotypes demonstrated a clear genetic differentiation between the two regions. This genetic break may reflect limited dispersal due to the species’ fossorial behavior or an oceanographic separation between the Yellow Sea and East Sea, possibly linked to the Korea Strait.