The family Xystodesmidae in the Korean Peninsula (Diplopoda: Polydesmida)

The polydesmidan family Xystodesmidae is reviewed with respect to the millipede fauna of the Korean Peninsula. It encompasses eight species in four genera: Xystodesmus Cook, 1895; Riukiaria Attems, 1898; Levizonus Attems, 1898; and Parafontaria Verhoeff, 1936. We redescribe five species of Xystodesmus including Xystodesmus pallidus (Verhoeff, 1937) and Xystodesmus amoenus (Takakuwa, 1942). Xystodesmus shirozui (Takakuwa, 1942) is new to the fauna of Korea. The enigmatic Pachydesmus bazanensis Takakuwa, 1942 is transferred to Xystodesmus as X. bazanensis comb. nov. A new species is described, X. bifurcus sp. nov. Of the other three genera, only one species of each is known from Korea, and they are as follows: Riukiaria koreana sp. nov. (from R. semicircularis (Takakuwa, 1941)), Levizonus circularis (Takakuwa, 1942) and Parafontaria koreana (Paik, 1963). Their validity and taxonomic position, based partly on new material, is discussed. Our maximum likelihood phylogeny, estimated based on concatenated sequences of mitochondrial COI and nuclear EF1-α, supported the monophyly of these four genera. Furthermore, the presence of subclades within these clades suggests potential genetic differentiation at the population level.