Characterization of the complete mitochondrial genome of the longhorn beetle, Batocera horsfieldi (Coleoptera, Cerambycidae) and its phylogenetic analysis with suitable longhorn beetles

Mitochondrial genome analysis is an important tool for studying insect phylogenet-ics. The longhorn beetle, Batocera horsfieldi, is a significant pest in timber, economic and protection forests. This study determined the mitochondrial genome of B. hors-fieldi and compared it with the mitochondrial genomes of other Cerambycidae with the aim of exploring the phylogenetic status of the pest and the evolutionary rela-tionships among some Cerambycidae subgroups. The complete mitochondrial ge-nome of B. horsfieldi was sequenced by the Illumina HiSeq platform. The mitochon-drial genome was aligned and compared with the existing mitochondrial genomes of Batocera lineolata and B. rubus in GenBank (MF521888, MW629558, OM161963, respectively). The secondary structure of transfer RNA (tRNA) was predicted using tRNAScan-SE server v.1.21 and MITOS WebSever. Thirteen protein-coding genes (PCGs) and two ribosomal RNA gene sequences of 21 longhorn beetles, including B. horsfieldi, plus two outgroups, Dryops ernesti (Dryopidae) and Heterocerus paral- lelus (Heteroceridae), were analyzed. The phylogenetic tree was constructed using maximum likelihood and Bayesian inference methods. In this study, we success-fully obtained the complete mitochondrial genome of B. horsfieldi for the first time, which is 15 425 bp in length. It contains 37 genes and an A + T-rich region, arranged in the same order as the recognized ancestor of longhorn beetles. The genome of B. horsfieldi is composed of 33.12% A bases, 41.64% T bases, 12.08% C bases, and 13.16% G bases. The structure, nucleotide composition, and codon usage of the new mitochondrial genome are not significantly different from other longhorn mi- tochondrial genomes. Phylogenetic analyses revealed that Cerambycidae formed a highly supported single clade, and Vesperidae was either clustered with Cerambyci-dae or formed a separate clade. Interestingly, B. horsfieldi, B. rubus and B. lineolata were clustered with Monochamus and Anoplophora species in both analyses, with high node support. Additionally, the Vesperidae Spiniphilus spinicornis and Vesperus sanzi and the 19 Cerambycidae species formed a sister clade in the Bayesian analy-sis. Our results have produced new complete mitogenomic data, which will provide information for future phylogenetic and taxonomic research, and provide a founda-tion for future relevant research.