| The Eristalini,a tribe belonging to the family Syrphidae of the order Diptera,is commonly known as the drone flies.They are mostly known for their adult members visiting flowers for nectar,while their larvae are predominantly detritivorous and aquatic in nature,possessing long respiratory tubes at their posterior end,earning them the name "rat-tailed maggots".The tribe Eristalini is known for its remarkable diversity and specificity,with over 1000 species belonging to more than 42 genera worldwide,and over 100 species across 14 genera in China.However,due to the complex morphological variations among the species,the taxonomic placement of the tribe Eristalini within Syrphidae,as well as the classification of some of its subgenera and even subtribes,has been the subject of intense debate.In this study,we reconstructed the species-level phylogenetic tree of the tribe Eristalini tribe by combining data sets from single-copy orthologous genes,mitochondrial genomes,and the cox1 gene.Our analysis provides preliminary insights into the monophyly of tribe Eristalini,the classification of its subtribes,and the taxonomic placement of its constituent genera and species,offering new molecular evidence for the systematic evolution of the tribe Eristalini and its various taxonomic hierarchies.The main results of this study are as follows:(1)Using second-generation genome sequencing platforms,we generated low-coverage genome data for 12 species of the tribe Eristalini tribe.Combined with the four publicly available the tribe Eristalini genome data in the NCBI database,we reconstructed the phylogenetic tree of 16 Eristalini species using 579 single-copy orthologous genes as the dataset,with representative species from closely related Bacchini,Syrphini,and Rhingiini tribes used as outgroups.Subsequently,we expanded the tribe Eristalini phylogenetic tree using 33 mitochondrial genome data(including 12 newly sequenced in this study),based on the phylogenetic tree constructed from the aforementioned single-copy orthologous genes as the backbone.Finally,we reconstructed the species-level phylogenetic tree of the tribe Eristalini,which includes 157 species from 13 genera within two subtribes,based on the cox1 gene using the mitochondrial genome tree as the backbone.(2)We report the completion of mitochondrial genome assembly and annotation of 12 species of aphid parasitoid wasps based on second-generation genome sequencing platforms:(1)Similar to most metazoans,the mitochondrial genomes of the parasitoid wasps are circular double-stranded DNA molecules with a length between 14,429 bp to 16,375 bp.With the exception of a few species,all contain 13 protein-coding genes(PCGs),2 ribosomal RNA genes(r RNAs),22 transfer RNA genes(t RNAs),and 1 control region(D-loop).The arrangement of mitochondrial genome genes is consistent with that of Drosophila yakuba,and no gene rearrangement was detected.(2)The mitochondrial genome of the parasitoid wasps shows a clear AT bias,with slight A and C biases observed in nucleotide usage.(3)The start codons of protein-coding genes in the mitochondrial genome of the parasitoid wasps are mostly standard ATN codons(ATA,ATT,ATC,and ATG),and the stop codons include the typical three codons TAA or TAG,as well as incomplete stop codons(TA or T).(3)This statement supports the monophyly of the tribe Eristalini and the subtribe Eristalina,but does not support the the monophyly of the subtribe Helophilina.(4)The subtribe Eristalina is monophyletic and located at the terminal end of the entire phylogenetic tree,and the genera Senaspis and Eristalis exhibit monophyly.Based on the presence or absence of bands on the face,it is supported to merge the genera Lathyrophthalmus(except for Lathyrophthalmus viridis),Eristalinus,and Eristalodes into one genus.(5)The subtribe Helophilina,located at the base of the entire phylogenetic tree,only shows monophyly in the genera Parhelophilus and Mesembrius.Helophilina can be divided into two major clades.The first clade consists of the basal genera Parhelophilus,Helophilus,and Lejops,which are sister to the remaining genera of the tribe Eristalini.The second clade,located closer to the tip of the tree,comprises the genera Mesembrius,Mallota,Myathropa,and Tigridemyia,and is more closely related to the subtribe Eristalina of traditional morphology-based classification. |
