The Complete Mitochondrial Genomes of Penthe kochi (Coleoptera: Tetratomidae) with Its Phylogenetic Implications.

To explore the mitogenome characteristics of Tetratomidae and the phylogenetic position of this family in Tenebrionoidea, the mitogenome of Penthe kochi Mařan, 1940 was sequenced, annotated, and analyzed. The P. kochi mitogenome is consistent with Tenebrionoidea species in gene length, genomic organization, codon usage, and secondary structures of transfer genes (tRNAs). Most protein-coding genes (PCGs) originate with a typical ATN start codon, except nad1 and nad3, which start with TTG. In total, 10 PCGs are terminated with complete stop codon TAA and TAG, while cox1, cox2, and nad 4 contain an incomplete stop codon T-. Among the 13 PCGs, nad2 (Pi = 0.282) has the most diverse nucleotide composition, and cox2 is the most conserved gene with the lowest value (Pi = 0.154). The Ka/Ks ratio of cox1 (0.076) and cox2 (0.124) has a lower value. All the tRNAs can be folded in a typical clover-leaf secondary structure, except trnS1, which lacked a dihydrouridine arm. And phylogenetic analyses were performed based on 13 PCGs using the Bayesian inference (BI) method. The results showed that the clade of Tenebrionoidea was well separated from the outgroups, and Tetratomidae and Mycetophagidae were not well resolved. Phylogenetic analyses with more mitogenome samplings are needed to resolve the phylogeny of Tenebrionoidea.