Scarus obishime is a rare parrotfish endemic to the Ogasawara Islands, located in the northwestern Pacific Ocean roughly 1,000 km south of the main Japanese archipelago. It was described as a new species in 1993. Since then it has been speculated to be closely related to Scarus ovifrons occurring on southern coasts of the main Japanese archipelago, but this has never been formally tested. To identify the closest relative of this rare parrotfish, we determined one nuclear (S7 ribosomal protein gene intron 1 [S7I1], ca. 600 bp) and two mitochondrial (control region [CR], ca. 400 bp and 16S rRNA, ca. 600 bp) partial DNA sequences for two specimens of the species and conducted molecular phylogenetic analyses using recently published sequences from 45 of the 52 described species of the genus and 16 of the 18 described species of Chlorurus. Nuclear and mitochondrial sequences were analyzed separately based on results of Basic Local Alignment Search Tool (BLAST) searches using the newly obtained sequences of S. obishime as queries. Phylogenies resulting from two single-region analyses (S7I1 and 16S rRNA) and the concatenation of the two mitochondrial regions (CR + 16S rRNA) supported a close phylogenetic affinity between S. obishime and S. ovifrons. In addition, nuclear (S7I1) analyses demonstrated that the two “East Asian” species formed a robust monophyletic group with the Arabian species Scarus arabicus, whereas mitochondrial data sets significantly rejected monophyly of the three species. This result seems to indicate a partially shared evolutionary history between the “East Asian” and Arabian lineages.
Molecular Phylogenetic Affinities of 
