Out of chaos: Phylogenomics of Asian Sonerileae.

Sonerileae is a diverse Melastomataceae lineage comprising ca. 1000 species in 44 genera, with >70% of genera and species distributed in Asia. Asian Sonerileae are taxonomically intractable with obscure generic circumscriptions. The backbone phylogeny of this group remains poorly resolved, possibly due to complexity caused by rapid species radiation in early and middle Miocene, which hampers further systematic study. Here, we used genome resequencing data to reconstruct the phylogeny of Asian Sonerileae. Three parallel datasets, viz. single-copy ortholog (SCO), genomic SNPs, and whole plastome, were assembled from genome resequencing data of 205 species for this purpose. Based on these genome-scale data, we provided the first well resolved phylogeny of Asian Sonerileae, with 34 major clades identified and 74% of the interclade relationships consistently resolved by both SCO and genomic data. Meanwhile, widespread phylogenetic discordance was detected among SCO gene trees as well as species trees reconstructed using different tree estimation methods (concatenation/site-based coalescent method/summary method) or different datasets (SCO/genomic/plastome). We explored sources of discordance using multiple approaches and found that the observed discordance in Asian Sonerileae was mainly caused by a combination of biased distribution of missing data, random noise from uninformative genes, incomplete lineage sorting, and hybridization/introgression. Exploration of these sources can enable us to generate hypotheses for future testing, which is the first step towards understanding the evolution of Asian Sonerileae. We also detected high levels of homoplasy for some characters traditionally used in taxonomy, which explains current chaotic generic delimitations. The backbone phylogeny of Asian Sonerileae revealed in this study offers a solid basis for future taxonomic revision at the generic level.

A new species of Bredia (Sonerileae, Melastomataceae) from Sichuan, China.

Bredia hispida (Sonerileae, Melastomataceae), a species occurring in southeastern Sichuan, China, is newly described based on morphological and molecular data. The generic placement of B. hispida is well supported by phylogenetic analysis and morphological characters, including basally cordate, hairy leaf blade, cymose inflorescence, basally gibbous anthers and enlarged ovary crown enclosing an inverted frustum-shaped depression. Both molecular and morphological divergence showed that B. hispida is well separated from its close relatives, justifying its recognition as a distinct species. The new species resembles B. repens, B. changii and B. guidongensis in the prostrate habit and isomorphic stamens but differs markedly in the unequal opposed leaves, the 2-4 mm long, stout bristles on the adaxial surface of leaf blade and acuminate leaf apex. Bredia hispida co-occurs with B. esquirolii in the wild. No morphologically putative hybrids between them were observed despite their overlap in flowering season. The isolating mechanism remains unclear, pending further investigation.

Recircumscription of Bredia and resurrection of Tashiroea (Sonerileae, Melastomataceae) with description of a new species T.villosa.

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.

A new species of Fordiophyton (Sonerileae, Melastomataceae) from Yunnan, China.

Fordiophytonjinpingense (Melastomataceae; Sonerileae), a species occurring in south-eastern Yunnan, China, is described as new, based on morphological and molecular data. Phylogenetic analyses, based on nrITS sequence data, showed that, except F.breviscapum, all species sampled in Fordiophyton formed a strongly supported clade in which two geographical lineages were recovered. The generic placement of F.jinpingense is well supported by phylogenetic analyses and a character combination of 4-merous flowers, distinctly dimorphic stamens and the connectives basally not calcarate. Molecular divergence and morphological evidence indicate that F.jinpingense is well separated from other members of the genus, thus justifying its recognition as a distinct species. Fordiophytonjinpingense is phylogenetically closest to F.repens, but differs markedly from the latter in stem morphology (short, obtusely 4-sided vs. long, 4-angular), habit (erect vs. creeping), leaf size (6-16.5 × 4.5-13 cm vs. 4-7.5 × 4-6.5 cm) and flower number per inflorescence (5-13 vs. 3-6).

The specific status of Melastoma kudoi (Melastomataceae, Melastomeae).

BACKGROUND: Melastoma has undergone rapid species radiation during the last one million years, and circumscription of some species in the genus has remained controversial. Melastoma kudoi, an erect species narrowly endemic to central Taiwan was previously treated as a synonym of M. intermedium, a semicreeping hybrid between the erect species M. candidum and the creeping M. dodecandrum, making its identity questionable. We addressed this question based on molecular and morphological data. RESULTS: Phylogenetic analyses based on nrITS sequence data revealed that M. kudoi is most closely related to M. dodecandrum. Further analyses of six nuclear genes (cam, chi, gapC, gbss, tpi and vr) and two chloroplast markers (trnL-trnF and psbA) showed that M. kudoi is well diverged from its close relatives. Morphologically, it is also easily distinguished from related species by its erect habit, center-positioned stigma, and spreading, basally enlarged hairs on the hypanthium. CONCLUSIONS: Both molecular phylogenetic and morphological data suggest that M. kudoi is well separated from M. intermedium, M. dodecandrum, and O. scaberrima, and should be treated as a distinct species. Taxonomic treatment and detailed description of M. kudoi are provided.