Comparative Analysis of Mitogenomes in Leafhopper Tribe Deltocephalini (Hemiptera: Cicadellidae: Deltocephalinae): Structural Conservatism and Phylogeny

Previous studies on the gene order and composition of leafhopper mitochondrial genomes have revealed a high level of conservation in overall genome structure. Some members of Deltocephalinae, the largest subfamily, exhibit tRNA gene rearrangements; however, few mitogenomes have been sequenced in this group and the degree of structural variation within tribes remains unclear. In this study, we sequenced the complete mitogenomes of 14 species belonging to four genera of tribe Deltocephalini from China and compared them with the two previously reported mitogenomes for this tribe. The studied mitogenomes showed a high degree of similarity to most other leafhopper mitogenomes in overall structure, mostly varying in the total length (14,961-15,416 bp) and number of non-coding A + T-rich regions. Gene size, order, arrangement, base composition, codon usage, and secondary structure of tRNAs in the newly sequenced mitogenomes were highly conserved in Deltocephalini, and variations in start/stop codon usage and tRNA secondary structure mostly matched those of other leafhoppers. Phylogenetic analysis of different combinations of protein-coding and ribosomal genes using maximum likelihood and Bayesian inference under different models using either amino acid or nucleotide sequences were generally consistent and agreed with the previous nuclear and partial mitochondrial gene sequence data, indicating that complete mitochondrial genomes are phylogenetically informative at different levels of divergence within Deltocephalini and among different leafhoppers species. In addition to Deltocephalini, Deltocephalinae included members of Athysanini and Opsiini formed monophyletic groups. Maximum likelihood and Bayesian inference analyses consistently grouped <i>Graminella nigrinota</i> with Paralimnini, rendering Deltocephalini polyphyletic. The topology consistently divided Deltocephalini into two major branches, with <i>Alobaldia tobae</i> and <i>Polyamia penistenuis</i> forming a well-supported sister group to the remaining species of the tribe.