Phylogenetic relationships and distribution of N ew W orld M elastomeae ( M elastomataceae)

In this study we present a phylogenetic analysis of M elastomeae, focusing on the N eotropical members of the tribe, a group of c . 70 species in 30 genera. In total, 236 species, including outgroups ( M iconieae and Merianieae) and representatives of the Microlicieae and Rhexieae, were sequenced for the nuclear ribosomal internal transcribed spacer ( nrITS) , and the plastid spacers accD ‐psaI and psbK‐psbL . Melastomeae are not resolved as monophyletic because a group of mostly herbs and small trees with mostly tetramerous flowers ( A canthella , A ciotis , A cisanthera , A ppendicularia , C omolia , E rnestia , F ritzschia , M arcetia , M acairea , N epsera , S andemania and S iphanthera ) is nested between R hexieae and M icrolicieae. The remaining N ew W orld M elastomeae are not resolved as monophyletic, because a group of O ld W orld genera ( O sbeckia , M elastoma , T ristemma and allied genera) are nested in the tribe. The large genus T ibouchina is not monophyletic because B rachyotum , B ucquetia , C astratella , C entradenia , C haetolepis , H eterocentron , I tatiaia , M icrolepis , M onochaetum , P ilocosta , Svitramia , and T ibouchinopsis are nested in it, even although all of these genera are recovered as monophyletic. Each major clade has remarkable habitat and geographical integrity. The clade formed by T ibouchina and allies appears to have arisen in savannas in lowland S outh A merica and later expanded to forest, campo and high A ndean biomes. At least two groups have radiated in eastern B razil, and two other groups in the A ndes and mountains of C entral A merica. Niche conservatism and colonization of adjacent environments seem to have driven speciation in N eotropical M elastomeae. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society , 2012, ●● , ●●–●●.