Phylogenetic relationships, character evolution and biogeographical analysis of the core Millettieae (Fabaceae, Papilionoideae)

The core Millettieae is an informal legume group with approximately 1000 woody species that are important components of pantropical floras. However, the generic relationships, character evolution, and biogeographic history of this group have remained challenging to resolve. In this study, we reconstruct comprehensive phylogenetic relationships based on nuclear and plastid sequences, covering all known genera and 35.7% of species diversity within the core Millettieae. Under this phylogenetic framework, we investigate the evolutionary patterns of 40 important characters and infer the biogeographic history of the core Millettieae. Results from phylogenetic analyses reveal 23 well‐supported clades distributed across two main groups within the core Millettieae. For the taxonomically complicated Millettia , six distinct African clades are recognized in both nuclear and plastid phylogenies. Results from character analyses highlight the taxonomic significance of flower‐related traits in the generic delimitation. Based on these findings, we propose reclassifying the African Millettia into five genera: two new genera ( Afropongamia , Cochlostylis ), two resurrected genera ( Berrebera , Fornasinia ), and one broadened genus ( Pongamiopsis ). A key to the 34 genera recognized here in the core Millettieae is provided. Additionally, results from molecular dating and biogeographic analyses suggest that the core Millettieae likely originated in Africa during the early Eocene and dispersed into Asia during the middle Eocene and into the Americas during the late Oligocene. The boreotropical migration likely accounts for early intercontinental disjunctions in the core Millettieae, while long‐distance dispersal might explain the later disjunctions. These findings provide novel insights into the taxonomy, phylogeny, and biogeography of the core Millettieae.