2009 年 14 巻 3 号 p. 157-164
Specimens of an undescribed species of Dasyatis stingray (D. sp.) were collected from Nagasaki and Kagoshima Prefectures, Japan. These specimens are more similar to D. akajei (Muller and Henle, 1841), D. laevigata Chu, 1960, and D. izuensis Nishida and Nakaya, 1988 than they are to other congeners obtained from the western North Pacific Ocean. The genetic differences among D. sp., D. akajei, D. laevigata, D. izuensis, and two other congeneric species, D. matsubarai Miyosi, 1939 and D. kuhlii (Muller and Henle, 1841), were investigated on the basis of partial sequences (621 bp) of the mitochondrial cytochrome oxidase subunit I (COI) gene. All three specimens of D. sp. that were analyzed showed identical haplotypes and formed a well-diverged clade in the phylogenetic analysis. The pairwise sequence differences between D. sp. and the five other species of Dasyatis ranged from 7.09% to 15.30%. These values almost equalled, or exceeded, the interspecific differences among the latter five species [range, 5.82% (D. akajei vs D. izuensis) to 16.43% (D. kuhlii vs D. izuensis, and D. kuhlii vs D. laevigata)]. Our findings indicate that D. sp. is a reproductively isolated and distinct species.