Abstract: Cyclorrhapha represents the most extensive adaptive radiation group within the Brachycera suborder of Diptera of Insecta, encompassing approximately 43% of the overall species diversity within this order. This group exhibits cosmopolitan distribution and enormously diverse living habits, and plays an important role in ecosystems. Cyclorrhapha is not only hotspots in multiple fields, including vector organisms, pollinators, forensic medicine insects and natural enemy insects, but also serves as a critical group for understanding the systematic evolution of Brachycera and its adaptive radiation, but its classification system is chaotic, and its phylogenetic relationship is far from clear. To reconstruct the phylogenetic relationships within the Cyclorrhapha, numerous dipterists have conducted investigations across various taxonomic levels employing diverse data types and methods. Cyclorrhapha is robustly supported as a monophyletic group, and it is further categorized into paraphyletic Aschiza and monophyletic Schizophora. There are about 103 families of 15 superfamilies in Cyclorrhapha. However, the systematic position of the member families of Platypezoidea and Syrphoidea, at the base of Cyclorrhapha remains contentious. The monophyly of Syrphoidea is inconsistent with morphological and molecular evidence, and the taxonomic status of several families within Schizophora, including Acartophthalmidae, Megamerinidae, Fergusoninidae, Mormotomyiidae, Marginidae, Sepsidae, Lonchaeidae and so on, is still ambiguous. Additionally, the elevation of certain subfamilies, such as Sciadoceridae, Tethinidae, Stenomicridae, Campichoetidae and Heteromyzidae, to family status is also debated. While significant advancements have been made in the phylogenetic research of Calyptratae, other groups within Cyclorrhapha are hindered by limited sampling coverage, uneven molecular data coverage, and a lack of fossil evidence, leaving many aspects of their phylogenetic relationships and evolutionary history unresolved. In this article, we systematically reviewed the historical changes of the classification systems of Cyclorrhapha, and comprehensively reviewed the current research progress of its phylogeny, summarized the existing phylogenetic controversy and the present status of genome data, and put forward relevant research suggestions, providing theoretical guidance for future explorations of the phylogenetic relationship and evolution history based on phylogenomics.

Key words: Diptera, Cyclorrhapha, taxonomy, phylogenetic, genome, evolution