Higher-level phylogeny and evolutionary history of nonditrysians (Lepidoptera) inferred from mitochondrial genome sequences

As one of the largest single-radiation sources of phytophagous insects, the higher level phylogeny of lepidopteran lineages has been debated for decades, especially the early divergences of nonditrysia. Here, we use 74 mitochondrial genomes representing seven nonditrysian superfamilies, including the newly sequenced mitochondrial genomes of eight families and 30 species. Four datasets were constructed and used for a phylogenetic analysis based on maximum likelihood (ML) and Bayesian inference (BI) methods. The results reveal that (1) nonditrysian lineages presented typically nested relationships with the family Micropterigidae as the sister-group to the remaining Lepidoptera, (2) monophyly of major clades in Lepidoptera, including Glossata, Heteroneura, Eulepidoptera and Ditrysia, was strongly supported, and (3) Neopseustoidea formed the sister of the remaining Glossata. Divergence-time analysis estimated that Lepidoptera originated c. 222 Mya during the Middle Triassic and that most superfamilies/families of nonditrysia originated from the Early Cretaceous to the Early Palaeogene, which largely coincided with the radiation of angiosperms. Additionally, three novel gene rearrangements in the gene cluster 'MIQ' and 'TP' were found in nonditrysian groups. Further mitochondrial genome data will help us to better understand the evolution of early nonditrysian lineages.