Mitochondrial Phylogeny and Historical Biogeography of Japanese Lotic-Breeding Salamanders Hynobius kimurae and H. fossigenus (Amphibia, Caudata)

The genetic structure of Hynobius kimurae and H. fossigenus, lotic-breeding salamanders widespread throughout montane regions of central and western Honshu of Japan, was surveyed. A mitochondrial DNA analysis to explore intraspecific genetic variation and infer the evolutionary population history of the two species was performed. Complete gene sequences of cytochrome b (Cyt b, 1141 bp) and cytochrome c oxidase subunit I (CO1, 1551 bp) were studied for 58 samples from 31 localities of H. kimurae and 22 samples from 12 localities of H. fossigenus, both encompassing the known range of the species. The two species proved to be monophyletic and H. kimurae included six clades grouped in four major clades (Clades West-1 from Northern Kinki, West-2 and West-3 from Hokuriku and Northern Chubu, West-5 and West-6 from Southwestern Kinki to Chugoku, and West-4 from Chubu to Kinki). Hynobius fossigenus consisted of two clades. In addition to East-1 from Kanto to easternmost Aichi, East-2 from eastern Aichi was herein first identified. Hynobius fossigenus occurs in the northernmost region among the lotic-breeding Hynobius species, whose range does not extend to the Tohoku District of northeast Japan. Our estimates indicate that H. fossigenus could not enter the region because of the presence of Paleo–Tokyo Bay and also of the hindrance through the ecological niche occupation by H. lichenatus, originally a lentic breeder but actually utilizing lotic water for breeding.