| So far,nearly 10,000 species of insects belonging to more than 860 types in 14 families have been described as "Symphyta" in Hymenoptera.Among them,the family Tenthredinidae,with nearly 4,500 species in 357 genera,is the largest family in the Symphyta group.Tenthredinidae belongs to Hymenoptera,which is in the superfamily Tenthredinoidea and the suborder Tenthredinomorpha.Tenthredinidae is generally divided into several subfamilies,including Nematinae,Selandriinae,Megabelesinae,Allantinae,Tenthredininae,Blennocampinae,Fenusinae,and Belesinae.Tenthredinidae is widely distributed group,found in all major animal geographic regions of the world except Antarctica.The Southeast Asian region,including China,is one of the centers of distribution for Tenthredinidae.The origin of Tenthredinidae coincides with the divergence time of early lineages of angiosperms.They have a wide range of host plants,and many species are important pests of agricultural,forestry,and horticultural plants.In-depth research on the systematic of the leafhopper family is of great scientific significance in the fields of insect systematics,evolution,and biological evolution research.However,there are still many problems with the higher-level classification of the Tenthredinidae,based on traditional taxonomic research,more than 20 classification systems have been proposed at the family level,with much controversy over subfamily and tribal classification.There have been relatively few studies based on molecular data,and discerning the phylogenetic relationships within Tenthredinidae based solely on morphological data is quite challenging.Therefore,it is necessary to study the phylogenetic relationships of Tenthredinidae based on mitochondrial genome sequencing and analysis,and to explore the origin and early evolution of Tenthredinidae based on this research.In this study,the mitochondrial genomes of 239 species from 141 genera were sequenced,and comparative analysis of the mitochondrial genomes of all species in each subfamily of Tenthredinidae was performed.Based on this,the phylogenetic relationships of Tenthredinidae were inferred,and the monophyly of each subfamily was investigated.Finally,based on the principle of monophyletic grouping,a new classification system for the higher-level taxa of Tenthredinidae was attempted to be constructed.The main results are as follows:1.The mean length of mitochondrial genomes from Allantinae,Belesinae,Blennocampinae,Caliroinae,Cladiinae,Dolerinae,Eriocampinae,Fenusinae,Heptameliinae,Heterathrinae,Hoplocampinae,Lycaotinae,Megabelesinae,Nematinae,Rocaliinae,Selandriinae,Strongylogasterinae and Tenthredininae is as follows:15348bp,15321 bp,15329bp,15476 bp,15250bp,14979 bp,15450bp,15203 bp,15206bp,15267 bp,15279bp,15911 bp,15797bp,15181 bp,15289bp,15386 bp,14820bp and 15247 bp.The mean A+T content of each subfamily is as follows: 80.5%,80.6%,80.7%,81.0%,80.5%,82.4%,81.1%,80.4%,80.3%,81.2%,79.6%,81.1%,82.5%,80.5%,81.3%,81.9%,81.3%,79.9%,has a significant bias towards AT base pairs.The mitochondrial gene structure and arrangement of each species are very similar to those of the existing Tenthredinidae species,including 13 protein-coding genes,22 t RNAs,two r RNAs,and one A+T rich region.2.The start codons for the 13 protein-coding genes in the 239 Tenthredinidae species use not only the common ATN codons,but also TTG,TTA,and GTG.The main stop codon is TAA,while TAG is an uncommon stop codon that appears in all subfamilies.The nad5 gene of 40 species in the Allantinae and the nad4 gene of all species in the Cladiinae,Heptameliinae,Heterathrinae,Hoplocampinae,Lycaotinae,and Strongylogasterinae have incomplete stop codons-T.The cob,nad4,and nad6 genes in all species of the Dolerinae have incomplete stop codons-T.3.Based on the 13 protein-coding genes and two r RNA genes of 239 Tenthredinidae species,21 species including Xyelidae,Blasticotomidae,Argidae,Pergidae,Athaliidae,Diprionidae,and Cimbicidae were selected as outgroups to construct the phylogenetic tree of Tenthredinidae using Maximum Likelihood(ML)and Bayesian Inference(BI),and a new classification system framework for Tenthredinidae was proposed:(1).Heptameliinae is located at the base of Tenthredinidae and is the sister group of all other groups within Tenthredinidae.Whether to retain its family-level status or merge it with Tenthredinidae is not contradictory to the phylogenetic tree.The paper retained its classification status as a family-level taxon.(2).The Nematinae group,consisting of Hoplocampinae,Nematinae,and Cladiinae,is a monophyletic group.This clade is the sister group of all other groups within Tenthredinidae except Heptameliinae.Based on this phylogenetic relationship,the Nematinae group is restored to family-level status.(3).Eriocampa and Conaspidia are not nested within Tenthredininae or Allantinae,and form a monophyletic group at the base of narrow Tenthredinidae.Based on this,a new subfamily,Eriocampinae,is established.(4).Strongyligasterinae,Selandriinae,Rocaliinae,and Dolerinae form a monophyletic group within Selandriinae.It is proposed to include these four subfamilies in Selandriinae and demote them to tribe rank.(5).Megabelesinae is a monophyletic group that is the sister group of the clade((Tenthredininae + Allantinae)+ Blennocampinae).(6).Tenthredininae and Allantinae form sister groups.The systematic relationships among the various tribes of Tenthredininae are:((Necolochelynini + Sioblini)+(Perineurini +(Macrophyini + Tenthredinini))).The systematic relationships among the tribes of Allantinae are:(Fernini +((Empriini + Allantiini)+((Empriini + Xenapateini)+ Allantiini))).(7).Belesinae,Caliroinae,Fenusinae,Heterathrinae,and Lycaotinae all fall within the Blennocampinae clade and together form a monophyletic group.Based on the internal branching structure of this clade,Blennocampinae is divided into 14 tribes:Lycaotini,Tomostethini,Phymatocerini,Anithoarthrini,Eutomostethini,Monophadnini,Heterathrini,Caliroini,Blennocampini,Pareophorini,Waldheimiini,Eusunoxini,Hemibelesesini,and Belesesini.(8).The systematic position of certain groups such as the Beldonea from the Tenthredininae,the Sinopoppia from Caliroinae,and the Dimorphopteryx from Allantinae cannot be determined at present.The paper compared,analyzed,and discussed the main differences between the new classification system and the original main classification system of Tenthredinidae. |
