he phylogenetic position of Cladiucha within Tenthredinidae based on comprehensive mitochondrial phylogenomics and the evidence from comparative analyses of rRNA secondary structure

Two mitogenomes of Cladiucha were newly reported and shown typical pattern of gene arrangement. The phylogenetic position of Cladiucha was obtained from tree reconstruction using various data treatment methods and substitution models. Significant heterogeneity in the nucleotide composition and mutational biases was found in the mitochondrial protein-coding genes, and the third codon position exhibited high levels of saturation. Therefore, 14 datasets were conducted under both site-homogeneous and site-heterogeneous models. The following conclusions were drawn from the phylogenetic analyses: (i) the monophyly of Tenthredinidae was confirmed, (ii) the monophyly of Allantinae + Tenthredininae + Megabelesinae was approved, and (iii) within the family, ((((Tenthredininae + Fenusinae) + Allantinae) + Megabelesinae) + Nematinae) is probably the most acceptable cladogram for the phylogeny of Tenthredinidae, which is also supported by the morphological analysis and a comparative study on the rRNA secondary structure. Divergence time estimation analyses indicated that diversification of the major superfamilies of the suborder Symphyta occurred around 232.9 Ma, and the splits of Tenthredinidae were dated to 146 Ma, which corresponding to the origin of the earliest lineages of flowering plants and major diversifications of core angiosperms, respectively. The Cladiucha arose in the Mid-Miocene; at that time, magnoliids are rapidly undergoing genus-species differentiation. "