Backbone of synthesis tree is a supertree (Bininda-Emonds et al, 2005, Syst Biol, 54) built from several mitogenome studies: Tong et al. (2022) The first complete mitochondrial genome of Hexagenia rigida Mc Dunnough, 1924 (Ephemeroptera: Ephemeridae) and its phylogeny. Mitochondrial DNA Part B, 7, 1093-1095. Guan et al. (2021) The complete mitochondrial genome of Choroterpes (Euthralus) yixingensis (Ephemeroptera: Leptophlebiidae) and its mitochondrial protein-coding gene expression under imidacloprid stress. Gene, 800, 145833. Wang et al. (2022) The complete mitochondrial genomes of Ephemera serica (Ephemeroptera: Ephemeridae) and phylogenetic analysis. Mitochondrial DNA B Resour., 7, 461-463. Xu et al. (2020) Six complete mitochondrial genomes of mayflies from three genera of Ephemerellidae (Insecta: Ephemeroptera) with inversion and translocation of trnI rearrangement and their phylogenetic relationships. PeerJ, 8, e9740. Xu et al. (2020) The mitochondrial genome of Caenis sp. (Ephemeroptera: Caenidae) from Fujian and the phylogeny of Caenidae within Ephemeroptera. Mitochondrial DNA Part B, 5, 192-193. Li et al. (2021) The First Two Complete Mitochondrial Genomes of Neoephemeridae (Ephemeroptera): Comparative Analysis and Phylogenetic Implication for Furcatergalia. Genes, 12, 1875. Xu et al. (2021) Insight into the Phylogenetic Relationships among Three Subfamilies within Heptageniidae (Insecta: Ephemeroptera) along with Low-Temperature Selection Pressure Analyses Using Mitogenomes. Insects, 12, 656. Synthesis tree constructed (Chesters, 2019, Syst Entom, 45) by adding multigene alignment of COI from BOLD, 16S, 18S, 28S, WG, EF1a from NCBI. 283 species with single outgroup Cordulegaster_boltonii. Known issues: poor intrageneric resolution in several cases, particularly Baetis. * If used in a publication, please cite Chesters, Ferrari, Lin, Orr, Staab, Zhu (2023) Launching insectphylo.org; a new hub facilitating construction and use of synthesis molecular phylogenies of insects. Molecular Ecology Resources 00, 1–18. ** If used in a publication, please cite Ratnasingham and Hebert (2007) BOLD: The Barcode of Life Data System (www.barcodinglife.org). Molecular Ecology Notes 7, 355-364.