The complete mitochondrial genomes (mitogenomes) of the tribes Coomaniellini and Dicercini were sequenced and described in this study, including Coomaniella copipes (16,196 bp), Coomaniella dentata (16,179 bp), and Dicerca corrugata (16,276 bp). These complete mitogenomes are very similar in length and encoded 37 typical mitochondrial genes, including 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs) and 13 protein-coding genes (PCGs). Most of PCGs had typical ATN start codons and terminated with TAR. Among these mitogenomes, Leu2 (L2), Ile (I), Ser2 (S2), and Phe (F) were the four most frequently encoded amino acids. Moreover, phylogenetic analyses were performed based on three kinds of nucleotide matrixes (13 PCGs, 2 rRNAs, and 13 PCGs + 2 rRNAs) among the available sequenced species of the family Buprestidae using Bayesian inference and Maximum-likelihood methods. The results showed that a Chrysochroninae species interspersed in Buprestinae, and Coomaniellini is more closely related to Dicercini than Melanophilini. Moreover, the clade of Buprestidae was well separated from outgroups and the monophyly of Agrilinae is confirmed again. Our whole mitogenome phylogenetic results support that the genus Dicerca can be transferred from Chrysochroinae to Buprestinae; whether Dicercini can be completely transferred remains to be further verified after enriching samples. Our results have produced new complete mitogenomic data, which will provide information for future phylogenetic and taxonomic research.

Background: The family Buprestidae is one of the largest families in Coleoptera; however, the number of reported mitochondrial genomes for this family is limited. Methods: In this study, mitogenomes of Chrysobothris violacea, C. shirakii, Buprestis fairmairei, and Phaenops yin were sequenced, assembled, and annotated. The mitogenomes of Chrysobothris, Phaenops, and Buprestis are reported for the first time. Results: The mitogenomes of Chrysobothris violacea, C. shirakii, and Phaenops yin are complete, while the mitogenome of Buprestis fairmairei is partial, lacking trnV and 12S genes. The AT-skew of these four mitogenomes is positive (0.02–0.09). Among the protein-coding genes, the Ka/Ks ratio for cox1 is the lowest (0.05), and the nucleotide diversity for nd6 is the highest. Conclusions: The phylogenetic trees based on mitogenome sequences suggest that the target genus Chrysobothris is sister to Phaenops, and the target genus Buprestis is sister to (Melanophila + (Chrysobothris + Phaenops)) clade. The results of this study will provide mitogenomic data for further research on the mitogenome and phylogeny of Buprestidae.

Three mitochondrial genomes of Chrysochroinae (Buprestidae) were sequenced and analyzed. The mitogenomes of the genera Catoxantha and Nipponobuprestis are first reportedand Chrysochroa opulenta is a first record for China. The complete mitogenomes of Catoxantha luodiana, Nipponobuprestis guangxiensis and Chrysochroa opulenta exhibit striking similarities in their lengths and composition. Specifically, their lengths are 15,594 bp, 15,775 bp and 15,587 bp, respectively. Each of these genomes encodes 37 typical mitochondrial genes. The overwhelming majority of protein-coding genes (PCGs) have the typical ATN (ATT, ATA, ATG or ATC) as the start codon and terminate with TAR (TAA or TAG) as the stop codon or an incomplete stop codon T-. Among the three mitogenomes, Leu2, Ser2 and Phe were the most frequently encoded amino acids. In the PCGs, the Ka/Ks ratio of cox1 is the lowest, whereas atp6 has the highest value. This suggests that cox1 can be used as a molecular barcode for species delimitation and phylogeny in Chrysochroinae. The phylogenetic results showed that C. luodiana and two Chrysochroa species formed a clade. Based on the topology of the phylogenetic tree, the genus Catoxantha should be reassigned as a subgenus of Chrysochroa.

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.

The number of known mitochondrial genomes in Buprestidae is limited, especially in Chrysochroinae, which seriously hinders the phylogenetic study of this family. The mitogenomes of Capnodis miliaris, Lamprodila cupreosplendens, Sphenoptera insidiosa and Philocteanus rubroaureus were sequenced, assembled and annotated in this study. The mitogenomes of these four species are typical circular double-stranded DNA molecules, containing 13 protein-coding genes (PCGS), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs), and a control region (CR). The total lengths of these four mitogenomes are moderate, ranging from 15,778 bp to 16,230 bp. Additionally, their A + T content ranges from 68.76% to 73.47%, showing positive AT-skew values ranging from 0.098 to 0.181. Relative Synonymous Codon Usage (RSCU) analysis indicated that TTT (Phe), ATT (Ile), TCT (Ser2), and TTA (Leu2) are the most frequently used codons. The gene arrangement of four mitogenomes is consistent with the previously reported Buprestidae mitogenomes. Most of the PCGs use ATN as the start codon, with TAA as the stop codon or an incomplete stop codon T-. Phylogenetic trees were constructed based on the PCGs and rRNAs using both maximum-likelihood and Bayesian inference methods. The phylogenetic results showed that Julodinae, Polycestinae, Buprestinae and Agrilinae are monophyletic groups, and Chrysochroinae is a paraphyletic group. As the number of Buprestidae mitogenomes used for polyogenetic analysis increases, the topology of phylogenetic tree shows differences compared to previous studies.