Abstract Chloropidae, commonly known as grass flies, is a hyper‐diverse family of true flies thriving in terrestrial ecosystems around the world with importance to conservation and economy. However, true grass fly diversity and evolutionary affinities are still largely unknown leading to an obscure classification at varied taxonomic levels. The massive lack of data on grass fly evolution hampers studies ranging from species discovery to diversification and provision of ecological services. To overcome this issue, we provide the first comprehensive phylogeny of worldwide Chloropidae using whole‐genome shotgun sequencing to retrieve mitochondrial genes, ultraconserved elements and single‐copy orthologs. With this, we generated genomic resources from all subfamilies, 95% of the tribes and 48% of the chloropid genera from all biogeographic regions which provides an invaluable resource for biodiversity studies worldwide. Overall, our results provide novel genomic data of over 100 fly species and our data confirm the monophyly of Chloropidae and relationship with Milichiidae, also supporting a reassessment of Chloropidae classification. We implemented dramatic changes in the grass fly classification system that redefine Siphonellopsinae, propose two new tribes, reassign the tribal position of 60 genera, and synonymize six suprageneric taxa. All three subfamilies—Chloropinae, Oscinellinae and Siphonellopsinae—and 19 tribes represent well‐supported clades based on Maximum Likelihood analyses. In addition, we reveal a novel synapomorphy for the family, elucidate grass fly sister‐group, and assess the utility of the mitochondrial genome alone to recover evolutionary relationships of recent lineages of flies. This study is fundamental to mitigate the neglect associated with grass flies through an unprecedented source of genomic data, ultimately providing a novel framework for understanding the rapid evolution of the last and most species‐rich radiation of flies.
Riccardi et al. (2026) studied this question.