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Onychodactylus koreanus, a hynobiid salamander species endemic to the Korean Peninsula, can be regarded as a strict ecological specialist, probably vulnerable to anthropogenic environmental modifications and climate change. We used mitochondrial cytochrome b gene to analyze the genetic diversity and phylogenetic structure of O. koreanus from 19 populations collected in an attempt to cover its major distribution within South Korea. A total of 76 haplotypes of O. koreanus obtained in our analyses could be subdivided into three phylogenetic clades, KR, NE and SE. Clade KR haplotypes occur in most of the regions throughout the Korean Peninsula with four distinct subclades (KR I-IV). Clade NE and SE haplotypes were only observed in two populations YY and YS, respectively. Haplotype sharing was scarce even among populations in geographical proximity, and most of the populations were represented by a single clade or subclade, indicating the low level of gene flow among populations. O. koreanus likely originated from the historical southward dispersal of its ancestral lineages following divergence from Chinese O. zhaoermii that was recovered as the sister of O. koreanus in our phylogenetic analysis. Our results have critical implications for the taxonomic status of O. koreanus and its long-term management plan.

Korean salamanders of the genus Hynobius are currently classified into 3 species, H. leechii, H. quelpaertensis, and H. yangi. To investigate the phylogenetic relationship of these species, we analyzed the partial sequence of mitochondrial cytochrome b gene (907 bp) of 197 specimens from 43 regions in South Korea. Of these specimens, 93 were additionally examined with 12S rRNA (799 bp). Based on the partial sequence of the mitochondrial cytochrome b gene and 12S rRNA, 89 and 36 haplotypes were defined, respectively, consisting of six subclades (H. leechii, H. quelpaertensis, H. yangi, HC1, HC2, and HC3). Among these subclades, the three subclades (HC1, HC2, and HC3) were clearly separated from the 3 previously reported species in the genus Hynobius. Pairwise sequence divergence between the six subclades ranged from 6.3 to 11.2% in cytochrome b gene and 2.0 to 4.3% in 12S rRNA. These results indicate there may be more divergent populations than the three currently described. Moreover, the estimation of divergence time revealed that the Hynobius species in South Korea diverged during the Miocene epoch, approximately 9 - 5 MYA. In addition, we confirmed the distribution of the three known species (H. leechii, H. quelpaertensis, and H. yangi) and determined the distributions of new, distinct groups (or subclades; HC1, HC1, and HC3). To more accurately establish the taxonomic status and population structure, further genetic, morphological, and ecological studies will be needed.