Exploring the mitogenomes of Batracomorphus (Hemiptera: Cicadellidae: Iassinae): new insights from structural diversity and phylogenomic analyses

Abstract

Comparisons of mitogenomes are widely used for species identification and to explore the phylogenetic relationship among insect taxa. Batracomorphus is the third most diverse and widely distributed genus in the Cicadellidae (Hemiptera). However, there have been no analyses of genome structure and phylogenetic relationships within the genus. To compensate for the paucity of genomic information in this genus, we sequenced novel complete mitochondrial genomes of 11 Batracomorphus species and combined these with 23 previously sequenced mitochondrial genomes to perform structural comparisons and phylogenomic studies. Our results reveal generally conserved mitogenome organization, with one case of tRNA gene rearrangement, with trnI-trnQ reversed to trnQ-trnI when compared with the ancestral arrangement. Analysis of the ratio of nonsynonymous (Ka) to synonymous substitutions (Ks) showed ATP8 is the fastest and COI is the slowest evolving gene. ND2 and ND6 have highly variable nucleotide diversity, whereas COI and ND1 exhibit the lowest diversity. Phylogenetic analysis of nucleotide sequences grouped Batracomorphus species into a clade within the subfamily Iassinae. Within Batracomorphus, 3 clades were reconstructed consistent with the observed gene rearrangement, indicating that such rearrangements can serve as reliable molecular markers supporting phylogenetic hypotheses. These clades also correspond to clusters of species recovered by morphometric analysis of aedeagal shape, suggesting that characters of the male genitalia traditionally used for species delimitation are phylogenetically informative. Molecular divergence time estimates indicate that most speciation events within Batracomorphus occurred between the Paleogene and Neogene. This study provides insight into the population genetics, molecular biology, phylogeny, and morphological evolution of the leafhopper subfamily Iassinae and its largest genus, Batracomorphus.