Characterization of the Complete Mitochondrial Genome of Salassa thespis (Lepidoptera: Saturniidae) and Comparison with Other Lepidoptera Species

Abstract

There are many species of Lepidoptera, but few complete mitochondrial genomes of Lepidoptera have been included in databases. Here, the complete mitochondrial genome sequence of Salassa thespis was isolated and characterized. It was 15,302 bp in length and contained 13 protein-coding genes (PCGs), two rRNA genes, 22 tRNA genes and an A + T-rich region. Among the 13 PCGs, the initiation codon of cytochrome c oxidase subunit 1 (cox1) was CGA, and the rest were ATN. The cox1 and cox2 genes had an incomplete stop codon T, while the rest terminated with TAA. Codon usage analysis showed that Phe, Ile, Leu and Asn were the most frequent amino acids, while Trp was the least. Like other Lepidopterans, some conserved motifs were found in the A + T-rich region, including a 17 bp poly-T guided by ATAGA, the AT-rich area and a poly-A element. Bayesian inference and maximum likelihood phylogenetic tree analysis based on 13 PCGs of S. thespis confirmed that it belonged to the Saturniidae family and showed the following relationship: (S. thespis + (Rhodinia fugax + Samia canningi)). The enrichment of mitochondrial DNA provides reference information for the study of the evolution and diversity of Lepidoptera insects.