Three new species of subterranean amphipods (Pseudocrangonyctidae: Pseudocrangonyx) from limestone caves in South Korea

Pseudocrangonyx Akatsuka & Komai, 1922 is the most diverse group of subterranean amphipods in the groundwater communities of Far East Asia. In Korea, the diversity of the group has been underestimated due to the records of morphological variants of Pseudocrangonyx asiaticus Uéno, 1934. To estimate the species diversity, we analyzed the morphological characteristics and conducted molecular analyses of specimens collected from Korean caves that we treated as morphological variants of P. asiaticus. We described three new subterranean pseudocrangonyctid amphipod species, P. deureunensis sp. nov., P. kwangcheonseonensis sp. nov., and P. hwanseonensis sp. nov., from the groundwater of limestone caves in South Korea. Additionally, we determined sequences of the nuclear large subunit ribosomal RNA and the mitochondrial cytochrome c oxidase subunit I gene of the new species for molecular analyses. Molecular phylogenetic analyses revealed that the three new species formed a monophylum together with P. joolaei Lee et al., 2020 and P. wonkimi Lee, Tomikawa & Min, 2020, which are species that are endemic to Korean caves.