Evolutionary changes in geographic distribution and larval host plants may promote the rapid diversification of montane insects, but this scenario has been rarely investigated. We studied rapid radiation of the butterfly genus Colias, which has diversified in mountain ecosystems in Eurasia, Africa, and the Americas. Based on a dataset of 150 nuclear protein-coding genetic loci and mitochondrial genomes, we constructed a time-calibrated phylogenetic tree of Colias species with broad taxon sampling. We then inferred their ancestral geographic ranges, historical diversification rates, and the evolution of host use. We found that the most recent common ancestor of Colias was likely geographically widespread and originated ~3.5 Ma. The group subsequently diversified in different regions across the world, often in tandem with geographic expansion events. No aspect of elevation was found to have a direct effect on diversification. The genus underwent a burst of diversification soon after the divergence of the Neotropical lineage, followed by an exponential decline in diversification rate toward the present. The ancestral host repertoire included the legume genera Astragalus and Trifolium but later expanded to include a wide range of Fabaceae genera and plants in more distantly related families, punctuated with periods of host range expansion and contraction. We suggest that the widespread distribution of the ancestor of all extant Colias lineages set the stage for diversification by isolation of populations that locally adapted to the various different environments they encountered, including different host plants. In this scenario, elevation is not the main driver but might have accelerated diversification by isolating populations.

A new genus, Cyclomacula Qiao & Wang, gen. nov., is established to accommodate a new species and three new combinations from China: C. medogensis Qiao & Wang, sp. nov., C. glaucinoptera (Collenette, 1934), comb. nov., C. dudgeoni (Swinhoe, 1907), comb. nov. and C. flavimacula (Moore, 1865), comb. nov. Images of adults and genitalia of all currently recognized Cyclomacula species are provided, with illustrations of wing venation of the type species in the new genus. A key to species of the genus is presented, along with DNA barcode data.

A new species, Daplasa medoga sp. nov., is described from Tibet, China. The new species can be distinguished morphologically from all other known Daplasa species by its male genitalia with a sagittate uncus and distally broadly crotched valvae. The validity of new species is well supported by the molecular phylogenetic analyses of one mitochondrial gene (COI) and two nuclear genes (EF-1α & RPS5), with a total length of 2,324 bp.