Systematics ofVignasubgenusLasiospron(Leguminosae: Papilionoideae: Phaseolinae)

Abstract

Abstract—A taxonomic treatment is herein provided for the six primarily Neotropical species ofVignasubg.Lasiospron. This subgenus is distinguished, in part, by its close relationship with Old WorldVignaspecies, but rather than having an Old WorldVignafloral asymmetry where distal floral parts can have a right-hand curvature (from a face-view perspective), distal parts ofVignasubg.Lasiospronflowers, like those of American Phaseolinae, curve to the left. Our proposed taxonomy reflects published phylogenetic analyses that resolve theVignasubg.Lasiospronspecies in a subclade of the primarily Old World clade of species ofVignasensu stricto.Vignasubg.Lasiospronis therefore distinctive in having a primarily neotropical distribution. Three of the sixVignasubg.Lasiospronspecies have an amphi-Atlantic distribution, which we suggest was achieved naturally by the ability of these species to disperse and colonize coastal habitats. Nomenclatural and taxonomic synonyms are reported, along with species descriptions and the biogeographical, genetic, and morphological evidence that argues for each of the sixVignasubg.Lasiospronspecies fitting a unified species concept.