Complete mitochondrial genome of a blue-tailed skinkPlestiodon capito(Reptilia, Squamata, Scincidae) and comparison with other Scincidae lizards

Vertebrate mitochondrial genomes (mitogenomes) are valuable for studying phylogeny, evolutionary genetics and genomics. To date, however, compared to other vertebrate groups, our knowledge about the mitogenomes of skinks (the family Scincidae), even of reptile, has been relatively limited. In the present study, we determined the complete mitogenome of a blue-tailed skinkPlestiodon capitofor the first time, and compared it with other skinks available in GenBank. The circular genome is 17,344 bp long, showing a typical vertebrate pattern with 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes and one control region (CR). The gene organization, nucleotide composition, and codon usage are similar to those from skinks previously published. Twelve out of 13 PCGs initiates with canonical start codon (ATG), while COX1 starts with GTG. The codon usage analysis revealed a preferential use of the Leu(CUN)(Leu1), Pro, and Thr codons with the A/U ending. All tRNAs inP. capitowere predicted to fold into typical clover-leaf secondary structure, except tRNA-Ser(AGY). The secondary structures of 12S rRNA and 16S rRNA comprises 34 helices and 56 helices, respectively. The alignment of thePlesitodonspecies CRs exhibited high genetic variability and rich A + T content. Besides, variable types and numbers of tandem repeat units were also identified in the CR ofPlestiodon. Phylogenetic analyses recoveredP. capitoas the sister species toP. tunganus; monophyly of the Scincidae is well supported. Our results will help to better understand structure and evolution of the mitochondrial DNA control region in reptiles as well as the evolutionary status ofP. capito, and to lay foundation for further phylogenetic study of skinks in a mitogenomic framework.