A comprehensive phylogeny and revised taxonomy illuminate the origin and diversification of the global radiation of Papilio (Lepidoptera: Papilionidae).

The swallowtail genus Papilio (Lepidoptera: Papilionidae) is species rich, distributed worldwide, and has broad morphological habits and ecological niches. Because of its elevated species richness, it has been historically difficult to reconstruct a densely sampled phylogeny for this clade. Here we provide a taxonomic working list for the genus, resulting in 235 Papilio species, and assemble a molecular dataset of seven gene fragments representing ca. 80% of the currently described diversity. Phylogenetic analyses reconstructed a robust tree with highly supported relationships within subgenera, although a few nodes in the early history of the Old World Papilio remain unresolved. Contrasting with previous results, we found that Papilio alexanor is sister to all Old World Papilio and that the subgenus Eleppone is no longer monotypic. The latter includes the recently described Fijian Papilio natewa with the Australian Papilio anactus and is sister to subgenus Araminta (formerly included in subgenus Menelaides) occurring in Southeast Asia. Our phylogeny also includes rarely studied (P. antimachus, P. benguetana) or endangered species (P. buddha, P. chikae). Taxonomic changes resulting from this study are elucidated. Molecular dating and biogeographic analyses indicate that Papilio originated ca. 30 million years ago (Oligocene), in a northern region centered on Beringia. A rapid early Miocene radiation in the Paleotropics is revealed within Old World Papilio, potentially explaining their low early branch support. Most subgenera originated in the early to middle Miocene followed by synchronous southward biogeographic dispersals and repeated local extirpations in northern latitudes. This study provides a comprehensive phylogenetic framework for Papilio with clarification of subgeneric systematics and species taxonomic changes enumerated, which will facilitate further studies to address questions on their ecology and evolutionary biology using this model clade.