Phylogeny of Pleiochiton (Melastomataceae, Miconieae): total evidence




The genus Pleiochiton, as traditionally circumscribed, comprises nine species of epiphytic shrubs endemic to the Atlantic Rain Forest in eastern Brazil. We present here the results of the phylogenetic analysis of four plastid DNA regions (accD-psa1, psbK-psbL, ndhF, atpF-atpH), another of nuclear DNA (internal transcribed spacer, ITS) and a third with morphological characters. The datasets were analysed separately and also combined (all plastid regions, ITS + plastid, morphology and all molecular + morphology). These analyses were made in order to access the phylogenetic relationships between the species of Pleiochiton and related species in other genera, and to establish the circumscription of the genus and understand character evolution within the clade. The genus is monophyletic and supported by high jackknife values in all analyses, which showed some resolution if Clidemia blepharodes and C. parasitica were included. The clade comprises the epiphytic species with succulent roots. Most species have a hypodermis with more than one layer of cells, and also glandular trichomes, bracteoles 2.1–5.0 mm long, calyx teeth and hypanthium ratio ranging from 0.4 to 1.2, oval–oblong petals longer than 4.3 mm, and oval–oblong seeds, with a transition zone between the raphal region and testa made up of differentiated cells. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162, 423–434.