Phylogenetic analysis of Microlicieae (Melastomataceae), with emphasis on the re-circumscription of the large genusMicrolicia

Abstract

Microlicieae are a monophyletic tribe comprising seven genera: Chaetostoma, Lavoisiera, Microlicia s.s., Poteranthera, Rhynchanthera, Stenodon and Trembleya. Microlicia s.s. includes 172 species predominantly distributed in the campo rupestre of Brazil. Its delimitation is complex because the generic boundaries, mostly with Lavoisiera and Trembleya, are unclear. Here we present a phylogenetic analysis for Microlicieae focusing on Microlicia s.s., with the specific goals: (1) to test the monophyly of Microlicia s.s.; (2) to investigate morphological characters that could help in circumscribing clades and/or genera in the tribe and (3) to provide an appropriate classification for Microlicia s.s. and related genera. This study was based on plastid (atpF-atpH, trnS-trnG), nuclear ribosomal (nrITS, nrETS) and nuclear low-copy (waxy) DNA sequences, through maximum likelihood and Bayesian inference analyses. The history of 12 morphological characters was estimated based on ancestral state reconstruction analyses. Our analysis shows Microlicia s.s. to be paraphyletic with Chaetostoma, Lavoisiera, Stenodon and Trembleya nested in it. Most characters traditionally used to diagnose these genera are homoplastic. We propose the inclusion of these four genera in a broadly circumscribed Microlicia s.l., and provide new combinations and names for their species. As here defined, Microlicieae has three genera, Rhynchanthera, Poteranthera and Microlicia s.l., Microlicia s.l. being the fourth richest genus in Melastomataceae with c. 245 species.