Mitogenomic phylogeny of Tetrigoidea (Insecta, Orthoptera), with a focus on the genus Zhengitettix

The mitochondrial genome (mitogenome) has been widely used to infer the phylogeny, origin and evolution of Orthopteran insects. Although several mitogenomic data have been used to study the phylogenetic relationships of Tetrigoidea (Orthoptera), the phylogenetic status of several subfamilies and tribes was still unclear due to the limited sampling of taxon. To further analyze the mitogenomic features and phylogeny of Tetrigoidea, five mitogenomes (Zhengitettix curvispinus, Z. hainanensis, Scelimena melli, Eucriotettix oculatus and Thoradonta yunnana) were sequenced and analyzed in this study, with Z. hainanensis being the newly published mitogenome and Z. curvispinus and S. melli being the complete mitogenomes. Nucleotide composition showed that more A and T bases than C and G bases were found in the sampled mitogenomes, with A- and C-skew. A large intergenic region containing tandem repeats was identified between trnS(ucn) and nad1 in the Z. curvispinus mitogenome. The protein-coding genes (PCGs) used ATG and TAA as the most common initiation and termination codons, respectively. The tRNAs showed a typical clover secondary structure in the Z. curvispinus. The A+T-rich region contained tandem repeats in Z. curvispinus. Phylogenetic analyses of Tetrigoidea based on the maximum likelihood (ML) and Bayesian inference (BI) method supported several non-monophyly subfamilies and tribes, such as Scelimeninae and Thoradontini. Divergence time results showed that Tetrigoidea is one of the basal branch of Orthoptera, with Batrachideinae splitting first, followed by Tripetalocerinae. The genera diverged over a relatively long period, expanding from the Jurassic to the Neogene. These results provide useful data for the study of the mitogenome characteristic of the Tetrigoidea and even the whole Orthoptera, and were basic resources for their phylogeny and evolution study.