Phylogeny and biogeography of Lonchocarpus sensu lato and its allies in the tribe Millettieae (Leguminosae, Papilionoideae)

The phylogenetic relationships between Lonchocarpus s.l. and allies were studied using Bayesian and parsimony independent and combined analyses of nuclear ribosomal DNA (5.8S and flanking internal transcribed spacers ITS1 and 2) and chloroplast DNA (trnL-trnF, matK) sequences. Topologies resulting from ITS and combined datasets were congruent, while the matK analysis resulted in poorly resolved hypotheses probably because of its low substitution rate. Our results support the monophyly of Apurimacia, Deguelia, Philenoptera, Piscidia, and Tephrosia and the polyphyly of Millettia. Lonchocarpus, as traditionally circumscribed, is paraphyletic, and subgenera and sections within it are also paraphyletic or polyphyletic with the exception of sect. Willardia which is monophyletic. In Lonchocarpus s.l., three large subclades can be recognized, here referred to as the Muellera, the Dahlstedtia, and the Lonchocarpus s.str. subclades. We propose recogition of these as three recircumscribed genera (Muellera, Dahlstedtia, Lonchocarpus) supported by morphological traits and major distribution ranges. The genera Bergeronia and Margaritolobium are synonymized with Muellera. Nineteen new combinations in Muellera and ten in Dahlstedtia are proposed, and five lectotypes are presented. Analysis of the molecular data reveals that (1) Lonchocarpus s.str. originated about 8.7 ± 0.05 Ma ago in Central America, in contrast to Dahlstedtia and Muellera that both arose in South America, 6.3 ± 0.05 Ma and 8.0 ± 0.09 Ma ago, respectively; (2) at least three migration events of Lonchocarpus have occurred from Central to South America, and one to Africa, the latter best explained by long distance dispersal across the Atlantic Ocean.