Abstract
Genetic differences between two widely sympatric and morphologically similar labrid species from the southern coasts of Japan, Pseudolabrus eoethinus (Richardson, 1846) and P. sieboldi Mabuchi and Nakabo, 1997, were investigated by examination of partial sequences of the mitochondrially-encoded 16S rRNA gene. For each species, 15 individuals representing three populations were sequenced. Among the individuals of P. eoethinus, only one showed evidence of a sequence difference, whereas nine haplotypes were found for P. sieboldi. Phylogenetic analyses using maximum parsimony and neighbor-joining methods, with a haplotype of Notolabrus gymnogenis (Gunther, 1862) as an outgroup, showed that the haplotypes of the two species of Pseudolabrus are reciprocally monophyletic. Sequence differences between the haplotypes of the two species ranged from 2.9% to 4.2% (3.3% on average), such being comparable to those among the three congeneric species Pseudolabrus guentheri Bleeker, 1862, P. miles (Bloch and Schneider, 1801), and P. biserialis (Klunzinger, 1879) (2.9-3.6%); furthermore, these differences corroborate the specific status of both of the species from Japan.
