Plastome and nuclear data unveils the evolutionary history and a new infrageneric classification of the pantropical papilionoid legume genus Macropsychanthus

Abstract With 58 species, the pantropical papilionoid legume genus Macropsychanthus (Leguminosae: Diocleae) has long posed taxonomic challenges. In this study, we reconstructed its evolutionary history and revised its infrageneric classification using a comprehensive phylogenetic framework based on our newly produced plastome and nuclear DNA data from 59 taxa, including 51 species of Macropsychanthus. Our analyses confirm the monophyly of the genus and its division into the subgenera Macropsychanthus and Platylobium, each characterized by both molecular and morphological traits. Within subg. Macropsychanthus, we identify six well-supported clades, here proposed as sections, each supported by synapomorphies and biogeographic patterns. Divergence dating places the origin of the genus in the Amazon during the Miocene (∼12 Mya), followed by rapid diversification and subsequent long-distance dispersals into South-east Asia and Africa, representing rare cases of amphi-Pacific rainforest disjunctions. Overall, this study resolves long-standing taxonomic uncertainties, establishes a stable infrageneric classification, and provides novel insights into the timing, geography, and drivers of diversification in Macropsychanthus. The genus emerges as a valuable model for investigating biome shifts, long-distance dispersal, and morphological convergence in tropical lianas.