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Revisiting the classification of Melastomataceae: implications for habit and fruit evolution

2019; Oxford University Press; Volume: 190; Issue: 1 Linguagem: Inglês

10.1093/botlinnean/boz006

1095-8339

Lucas F. Bacci, Fabián A. Michelangeli, Renato Goldenberg,

Plant and animal studies

Bertolonieae (Melastomataceae) have traditionally comprised > 100 Neotropical species in Bertolonia, Boyania, Macrocentrum, Monolena, Salpinga and Triolena and another six species in the monospecific genera Diolena, Diplarpea, Maguireanthus, Opisthocentra, Tateanthus and Tryssophyton. The position of the tribe inside or outside Sonerileae has been discussed since the first classifications of Melastomataceae. These tribes were always considered closely related because of overall similar morphology, mainly herbaceous habit and angular fruits. Previous phylogenetic analyses have shown that Bertolonieae as traditionally circumscribed are not monophyletic and require re-evaluation. These previous results also led to questions on why such herbaceous plants from shaded, moist habitats and with angular fruits had evolved so many times in different and geographically/phylogenetically distant groups of Melastomataceae. We conducted molecular phylogenetic analyses in order to evaluate tribal and generic limits, reconstruct morphological patterns and identify clades in the tribe. To infer the monophyly of Bertolonieae and the genera that were traditionally included in the tribe we analysed three plastid (ndhF, rbcL and rpl16) and two ribosomal (nrETS and nrITS) DNA markers, using maximum likelihood and Bayesian inference in individual and variously combined data sets comprising up to 6646 characters and 445 terminals. Bertolonieae as traditionally recognized were recovered in four major lineages across the tree. Bertolonieae are recircumscribed here to include only Bertolonia. A new tribe, Trioleneae, with the genera Monolena and Triolena is described on the basis of molecular, geographical and morphological evidence. Our study also shows that the combination of herbaceous habit and angular capsules has evolved several times in Melastomataceae. Besides the taxonomic changes proposed here, the molecular corroboration that Bertolonieae s.l. are not monophyletic and the geographical and morphological congruence found in these lineages, the convergence of morphological characters historically used to identify Bertolonieae s.l. might be explained by the occupation of similar habitats in different places across the world, i.e. in mostly shaded and moist herbaceous layers under the rainforest canopy. The dependence on water for seed dispersal and the limited dispersability could also explain the restriction of the taxa to a limited area or vegetation type.