Mitochondrial genomes of the stoneflies Mesonemoura metafiligera and Mesonemoura tritaenia (Plecoptera, Nemouridae), with a phylogenetic analysis of Nemouroidea

In this study, two new mitochondrial genomes (mitogenomes) of Mesonemoura metafiligera and Mesonemoura tritaenia from the family Nemouridae (Insecta: Plecoptera) were sequenced. The Mesonemoura metafiligera mitogenome was a 15,739 bp circular DNA molecule, which was smaller than that of M. tritaenia (15,778 bp) due to differences in the size of the A+T-rich region. Results show that gene content, gene arrangement, base composition, and codon usage were highly conserved in two species. Ka/Ks ratios analyses of protein-coding genes revealed that the highest and lowest rates were found in ND6 and COI and that all these genes were evolving under purifying selection. All tRNA genes in nemourid mitogenomes had a typical cloverleaf secondary structure, except for tRNA(Ser(AGN)) which appeared to lack the dihydrouridine arm. The multiple alignments of nemourid lrRNA and srRNA genes showed that sequences of three species were highly conserved. All the A+T-rich region included tandem repeats regions and stem-loop structures. The phylogenetic analyses using Bayesian inference (BI) and maximum likelihood methods (ML) generated identical results. Amphinemurinae and Nemourinae were sister-groups and the family Nemouridae was placed as sister to Capniidae and Taeniopterygidae.