Two mitochondrial genomes and the phylogenetic relationships of Silpha (Coleoptera: Staphylinidae: Silphinae)

Abstract

Silpha carinata (Herbst, 1783), and Silpha perforata (Gebler, 1832) (Coleoptera: Staphylinidae) belong to the tribe Silphini, which holds forensic significance due to its species’ rapid colonization of cadavers and relatively long developmental duration. In this study, we reported the complete mitochondrial genomes of S. carinata and S. perforata, representing the first fully sequenced mitochondrial genomes for the genus Silpha. These genomes were acquired via next-generation sequencing and then thoroughly characterized. We examined their sequence structure, base composition, codon usage bias, and the secondary structures of tRNA genes. Phylogenetic trees were generated using Bayesian inference (BI) and maximum likelihood (ML) methods. The results revealed that the mitochondrial genomes (mtDNA) of the two species are 16,322 bp (S. carinata) and 15,469 bp (S. perforata) in length, respectively, containing 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, and two ribosomal RNA (rRNA) genes. Their gene arrangement is highly conserved compared to other Coleoptera species. The mtDNA exhibit a significant AT bias, with A+T contents of 74.6% (S. carinata) and 74.4% (S. perforata). Among the 22 tRNA gene secondary structures, the tRNA-Phe and tRNA-His genes of both S. carinata and S. perforata lack the TψC arm. In contrast, all other tRNA genes can fold into the canonical cloverleaf secondary structure. Phylogenetic analyses support the monophyly of the genus Silpha, with S. carinata and S. perforata showing close evolutionary relationships. This research enhances our understanding of mitochondrial genomics and the evolutionary relationships within Silphinae.