Complete sequence determination and analysis of mitochondrial genome of Epiverta chelonia(Mader, 1933) (Coleoptera: Coccinellidae)

【Objective】 The purpose of the study was to clarify the structural characteristics of the mitochondrial genome of Epiverta chelonia(Mader, 1933) and analyze its phylogenetic relationship, so as to provide data support for the study of the origin, differentiation and genetic diversity of E. chelonia.【Method】 The mitochondrial genome of E. chelonia was sequenced by using Illumina next-generation sequencing technology, and the genome sequence was annotated and analyzed. Maximum likelihood and Bayesian methods were used to construct the phylogenetic evolutionary tree based on the 13 protein-coding genes(PCGs) of mitochondrial genomes of 11 species of insects from 3 subfamilies of Coccinellidae(Epilachninae, Coccinellinae and Scymninae).【Result】 The mitochondrial genome of E. chelonia was 17347 bp in length, including 37 genes(13 PCGs, 22 tRNA genes, 2 rRNA genes) and one non-coding region, 11 gene overlapping regions and 9 gene spacer regions. The genome had the typical gene organization and sequence of mitochondrial genome from Coleoptera insects, with the AT content of 75.77%, showing obvious AT skew. Among the 13 PCGs, all genes used ATN as the start codon, except for cox1 gene, which used TTG as the start codon. Eleven genes used TAA as the termination codon, only nad1 and nad3 genes used TAG as the termination codon. Except for trnS1 gene, the secondary structures of the remaining 21 tRNAs were the typical clover-leaf structure, with a small number of mismatches of G-U base in the secondary structure. Phylogenetic analysis showed that E. chelonia and Subcoccinella vigintiquatuorpunctata were on the same branch.【Conclusion】 The mitochondrial genome of E. chelonia conforms to the general characteristics of Coccinellidae mitochondrial genome. E. chelonia is closely related to S. vigintiquatuorpunctata, which is in accordance with the traditional morphological classification.