We determined the complete mitogenome of Pyrrhocoris tibialis (Hemiptera: Heteroptera: Pyrrhocoridae) to better understand the diversity and phylogeny within Pentatomomorpha, which is the second largest infra-order of Heteroptera. Gene content, gene arrangement, nucleotide composition, codon usage, ribosomal RNA (rRNA) structures, and sequences of the mitochondrial transcription termination factor were well conserved in Pyrrhocoroidea. Different protein-coding genes have been subject to different evolutionary rates correlated with the G + C content. The size of control regions (CRs) was highly variable among mitogenomes of three sequenced Pyrrhocoroidea species, with the P. tibialis CR being the largest. All the transfer RNA genes found in Pyrrhocoroidea had the typical clover leaf secondary structure, except for trnS1 (AGN), which lacked the dihydrouridine arm and possessed an unusual anticodon stem (9 bp vs. the normal 5 bp). A total of three different phylogenetic relationships among the five super-families of Pentatomomorpha were obtained using three analytical methods (MrBayes and RAxML under site-homogeneous models and PhyloBayes under a site-heterogeneous CAT + GTR model) and two mitogenomic datasets (nucleotides and amino acids). The tree topology test using seven methods statistically supported a phylogeny of (Aradoidea + (Pentatomoidea + (Lygaeoidea + (Pyrrhocoroidea + Coreoidea)))) as the best topology, as recognized by both RAxML and MrBayes based on the two datasets.

Tenebrionidae is widely recognized owing to its species diversity and economic importance. Here, we determined the mitochondrial genomes (mitogenomes) of three Tenebrionidae species (Melanesthes exilidentata, Anatolica potanini, and Myladina unguiculina) and performed a comparative mitogenomic analysis to characterize the evolutionary characteristics of the family. The tenebrionid mitogenomes were highly conserved with respect to genome size, gene arrangement, base composition, and codon usage. All protein-coding genes evolved under purifying selection. The largest non-coding region (i.e., control region) showed several unusual features, including several conserved repetitive fragments (e.g., A+T-rich regions, G+C-rich regions, Poly-T tracts, TATA repeat units, and longer repetitive fragments) and tRNA-like structures. These tRNA-like structures can bind to the appropriate anticodon to form a cloverleaf structure, although base-pairing is not complete. We summarized the quantity, types, and conservation of tRNA-like sequences and performed functional and evolutionary analyses of tRNA-like sequences with various anticodons. Phylogenetic analyses based on three mitogenomic datasets and two tree inference methods largely supported the monophyly of each of the three subfamilies (Stenochiinae, Pimeliinae, and Lagriinae), whereas both Tenebrioninae and Diaperinae were consistently recovered as polyphyletic. We obtained a tenebrionid mitogenomic phylogeny: (Lagriinae, (Pimeliinae, ((Tenebrioninae + Diaperinae), Stenochiinae))). Our results provide insights into the evolution and function of tRNA-like sequences in tenebrionid mitogenomes and contribute to our general understanding of the evolution of Tenebrionidae.