抄録
Allozyme studies demonstrated that wild medaka consist of four genetically distinct groups: the Northern Population from the Sea of Japan coast of eastern Japan, the Southern Population from the Pacific coast of eastern Japan and from western Japan, the East Korean Population from eastern and southern Korea, and the China-West Korean Population from China and western Korea. The boundaries separating the geographic distributions of these four groups are clear, and major divergences among groups were observed. Nucleotide sequences of the complete cytochrome b gene clarified the phylogenetic relationships among four groups. The phylogenetic tree based on cytochrome b nucleotide sequences indicated Japanese three major clades（A, B and C） . The geographic distribution of mitotypes in clades A and B was fully concordant with the Northern and Southern Populations defined by allozymes, while mitotypes in clade C were found only in the Kanto district. For Korean and Chinese medaka, phylogenetic trees indicated two major clades, D and E, which were different from the Japanese clades（A, B and C）. The geographic distribution of the mitotypes in clades D and E was consistent with the China-West Korean Population and the East Korean Population, respectively, as defined by allozymic analyses. Subsequently, the China-West Korean Population was described as a new subspecies O. latipes sinensis by morphological differences in 1989, and recently, the Northern Population as a new species O. sakaizumii. Here I propose “O. latipes complex”, a species complex including four distinct species, O. latipes（Southern Population） , O. sakaizumii（Northern Population） , O. sinensis（China-West Korean Population）, and Oryzias sp.（East Korean Population）, as the name corresponding to traditional “O. latipes”（the medaka or Japanese medaka）
