Abstract
The genus Themus Motschulsky, 1858 is one of the largest genera of beetle family Cantharidae, however, no complete mitochondrial genome is available in the public database so far. Here, we sequenced and analyzed the first complete mitochondrial genome of Themus, with T. foveicollis as the representative species. The mitochondrial genome was 16,469 bp in size with 37 genes including 13 protein-coding genes (PCGs), 22 transfer RNA genes, and two ribosomal RNA genes, as well as a non-coding region, which are arranged in the same way as the hypothetical ancestral insect. It exhibited a typical high A + T bias and a higher proportion of bases A and C than T and G (A: 41.1%, T: 37.5%, G: 8.6%, C: 12.9%). The phylogenetic trees of Elateroidea were reconstructed based on 13 PCGs sequences using the Bayesian inference (BI) and maximum-likelihood (ML) analyses to investigate its phylogenetic position. The results showed that Themus was consistently grouped with the remaining genera of Cantharidae and placed in a monophyletic clade of Cantharinae in high supporting values, which are congruent with the morphological classification. The newly sequenced mitochondrial genome in this study constitutes important reference data for reconstructing phylogeny of the family Cantharidae or the superfamily Elateroidea.