Comparison of the mitochondrial genomes of East Asian Pseudolabrus fishes

We determined the complete mitochondrial genomes of Pseudolabrus sieboldi and P. eoethinus, and analyzed the genome organization, codon usage, and transition/transversion mutation ratio of the mitochondrial genome. The mitochondrial genomes of P. sieboldi and P. eoethinus are 16,507 and 16,508 bp in length, respectively, and consisted of 37 genes (13 protein-coding genes, two ribosomal RNAs, and 22 transfer RNAs), which is typical for vertebrate mitochondrial DNA. All protein-coding genes of two species used the initiation codon ATG except the cytochrome c oxidase subunit (CO) 1, which began with GTG as an initiation codon. However, the termination codon for the NADH dehydrogenase subunit (ND) 6 gene encoded with TAA in P. sieboldi, and TAG in P. eoethinus. The 12S and 16S rRNA genes were 949 and 1694 bp, respectively, in P sieboldi, and were 948 and 1693 bp in P. eoethinus. The A+T content of the two rRNA genes were 52.9% in P. sieboldi and 52.5% in P. eoethinus, which is slightly lower than that of other labrid species. The identity of the 13 protein-coding genes ranged between 67% (ND6) and 94% (CO2 and ATP8). The G+C contents of all of the protein-coding genes of P. sieboldi were slightly higher than those of P. eoethinus. Our data contribute to the identification, and further our understanding, of the comparative genetics of Pseudolabrus species distributed in East Asia.