Sonerileae/Dissochaeteae (Melastomataceae) comprises ca. 50 genera, two thirds of which occur in Southeast Asia. Phylogenetic relationships within this clade remain largely unclear, which hampers our understanding of its origin, evolution, and biogeography. Here, we explored the use of chloroplast genomes in phylogenetic reconstruction of Sonerileae/Dissochaeteae, by sampling 138 species and 23 genera in this clade. A total of 151 complete plastid genomes were assembled for this study. Plastid genomic data provided better support for the backbone of the Sonerileae/Dissochaeteae phylogeny, and also for relationships among most closely related species, but failed to resolve the short internodes likely resulted from rapid radiation. Trees inferred from plastid genome and nrITS sequences were largely congruent regarding the major lineages of Sonerileae/Dissochaeteae. The present analyses recovered 15 major lineages well recognized in both nrITS and plastid phylogeny. Molecular dating and biogeographical analyses indicated a South American origin for Sonerileae/Dissochaeteae during late Eocene (stem age: 34.78 Mya). Two dispersal events from South America to the Old World were detected in late Eocene (33.96 Mya) and Mid Oligocene (28.33 Mya) respectively. The core Asian clade began to diversify around early Miocene in Indo-Burma and dispersed subsequently to Malesia and Sino-Japanese regions, possibly promoted by global temperature changes and East Asian monsoon activity. Our analyses supported previous hypothesis that Medinilla reached Madagascar by transoceanic dispersal in Miocene. In addition, generic limits of some genera concerned were discussed.

Phyllagathis Blume and Bredia Blume (Sonerileae s.l., Melastomataceae) are two closely related Asian genera with similar morphology and overlapping geographical range. Their generic circumscription and phylogenetic relationships are far from fully understood. We present here a molecular phylogenetic investigation for the two genera using nuclear ribosomal internal transcribed spacer and chloroplast (trnV‐trnM) sequence data. Seventeen genera of Sonerileae s.l. were included in the analyses, with Phyllagathis and Bredia densely sampled to cover their geographical range and morphological diversity. We identified 14 well supported species clusters within Sonerileae s.l.–Medinilla. Phylogenetic analyses together with reconstruction of morphological characters clearly indicated the taxonomic mess in generic delimitation of Sonerileae s.l. Many of the characters traditionally used in generic delimitation were highly homoplasious. Bredia and Phyllagathis, as well as Allomorphia, Anerincleistus, Fordiophyton, and Oxyspora, were revealed to be non‐monophyletic. Bredia, as currently defined, contains two groups of species with different phylogenetic affiliations. Bredia should be recircumscribed to exclude the Bredia–Phyllagathis clade I and accommodate the Bredia–Phyllagathis clade II as the type of the genus is included in the latter clade. Most species sampled in Phyllagathis spread across eight well supported clades throughout the phylogenetic tree. The type of Phyllagathis showed no close affiliation with other members of Phyllagathis nor its putative relatives. Phyllagathis, as presently circumscribed, is heterogeneous, encompassing multiple evolutionary lineages. As sequence data of nuclear ribosomal internal transcribed spacer and chloroplast trnV‐trnM failed to resolve the phylogenetic relationships among these lineages, the formal taxonomic adjustment of Phyllagathis is postponed until further evidence can be gathered.

BackgroundSpecies of Begonia are richly represented in limestone karst areas across the Sino-Vietnamese border. More than one hundred species were known, many of which were documented recently.ResultsIn continuation of our systematic studies of Asian Begonia, we report six species of Begonia that are unknown to science, namely B. caobangensis [sect. Platycentrum], B. circularis, B. melanobullata, B. langsonensis, B.locii and B. montaniformis [sect. Coelocentrum] from Northern Vietnam. Diagnostic features that separate them from morphologically allied species are provided. Somatic chromosome numbers were determined, which supports their placement in the respective sections. Foliar SEM microphotographs were taken and described.ConclusionA careful study of the literature, herbarium specimens and living plants, both in the wild and in cultivation in the experimental greenhouse, supports the recognition of the six new species, which are described and illustrated.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-015-0089-3) contains supplementary material, which is available to authorized users.

The Philippine island of Palawan is highly biodiverse. During fieldwork there in 2011 & 2014 we found five unknown species in the large genus Begonia. The species are similar in their rhizomatous stems, four-tepaled flowers, inferior two- or three-locular ovaries with bilamellate placentas, and are assignable to Begonia sect. Baryandra. Our observations support the recognition of these as five new species endemic to Palawan: B. elnidoensis, B. gironellae, B. quinquealata, B. tabonensis and B. tenuibracteata which are described here. The five new species were added to phylogenies based Bayesian analysis of nrDNA (ITS) and chloroplast DNA (ndhA, ndhF-rpl32, rpl32-trnL, trnC-trnD), along with 45 other allied ingroup species. A majority of the species show incongruent positions in the two phylogenies, with evidence of prevalent chloroplast capture. Models show chloroplast capture is more likely in plant populations with high levels of inbreeding following a reduction in selfing rate after hybridisation; we suggest that this is a possible explanation for the massive amount of chloroplast exchange seen in our phylogeny, as Begonia species often exist as small isolated populations and may be prone to inbreeding depression. Our data also indicate a level of nuclear genetic exchange between species. The high prevalence of hybrid events in Begonia is potentially an important factor in driving genomic change and species evolution in this mega-diverse genus.

Bredia (Melastomataceae) is an Asian genus that extends from central and southern mainland China to Taiwan and the Ryukyu islands. Molecular phylogenetic analyses reveal that the type of Bredia is nested in a clade of 20 species, while Tashiroea, a genus previously synonymized in Bredia, falls in another distantly related clade of 10 species. Our morphological survey shows that the two clades can be distinguished by several diagnostic features including leaf indumentum, texture, leaf surface sculpture under SEM, presence/absence of yellowish uniseriate trichomes, and capsule morphology. Based on molecular and morphological evidence, Bredia is recircumscribed and Tashiroea is resurrected. Description and a list of species are provided for the two genera with the description of a new species, T.villosa.