Integrative Taxonomy Improves Species Delimitation in the Neotropical Papilionoid Legume Genus <i>Platypodium</i>

Abstract— The neotropical papilionoid legume genus Platypodium comprises trees widely distributed across savannas, seasonal dry tropical forests (SDTF), and rain forests, from the northern boundary of Panama to the south of Brazil. The genus is mainly recognized by the combination of leaves up to 20-foliolate, mucronate leaflets, truly papilionate flowers that are clearly differentiated into an upper standard, lateral wing petals, and lower keel petals, 10 diadelphous stamens (4 + 4 and two free filaments), and an unusual samara-like fruit where the seed chamber is apical and the wing basal. Platypodium has been phylogenetically placed in the Pterocarpus clade of the tribe Dalbergieae sensu lato. Since the description of Platypodium in 1837, many names of species and infraspecific taxa were proposed, which gave rise to an intricate taxonomy. Despite Platypodium being the focus of recent studies, there are still doubts as to the morphological variation of populations that make its taxonomic delimitation difficult, especially in the size and shape of leaves, flowers, and fruits. An integrative taxonomy approach involving statistical morphometric analysis of morphological and ecological data has enabled us to produce a more sound delimitation of the species traditionally classified in the genus. The analyses revealed clear breaks in geographic and bioclimatic spaces, which might also be indicative of reproductive isolation. We recognize three species of Platypodium , one of which is newly described. We also present descriptions for the genus and species, as well as comments and illustrations for all species.