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  1. Fulltext Two new species of Begonia, B. moneta and B. peridoticola (Begoniaceae) from Sabah, Malaysia
    Peng CI, Lin CW, Repin R, Kono Y, Leong WC, Chung KF
    Bot Stud, 2015 Dec;56(1):7.
    PMID: 28510816 DOI: 10.1186/s40529-015-0087-5
    BACKGROUND: Mount Kinabalu, reknowned for its high biodiversity and endemism, is a National Park in the State of Sabah on the northern end of the island of Borneo. Every year many visit the higher part of the Kinabalu National Park, while most lowland forests in the Park are under-explored. Two unknown species of Begonia were collected from a peridotic (ultramafic) cliff in the Kinabalu National Park at ca. 400 m elevation.

    RESULTS: The two species are named B. moneta C.-I Peng, Rimi & C. W. Lin and B. peridoticola Rimi, C.-I Peng & C. W. Lin. Begonia moneta (sect. Baryandra) is similar to B. gueritziana Gibbs, a widespread species of the same section in Borneo, differing in the peltate (vs. basifixed) leaves and the smaller flower parts. Also, their chromosome numbers are different (B. moneta, 2n = 30; B. gueritziana, 2n = 28). The peltate and succulent foliage of B. moneta is also reminiscent of B. burttii Kiew & S. Julia and B. payung S. Julia & Kiew, both of sect. Reichenheimia, from Sarawak. Begonia moneta is distinct from the two species in having branched (vs. entire) placental lamellae. Additionally, B. moneta differs from B. burttii in having 4 (vs. 5) tepals in pistillate flowers and markedly unequal (vs. equal) fruit wings. Begonia moneta differs from B. payung in the smaller leaves and conspicuously winged (vs. wingless) capsules. Begonia peridoticola (sect. Petermannia) resembles B. punchak Kiew & S. Julia from limestone areas in Kuching Division, Sarawak, differing in the entire leaf margin (vs. distantly dentate), much larger capsular wings (8-11 mm vs. 2-3 mm wide) and yellow, spiral (vs. crimson, U-shaped) styles.

    CONCLUSION: A careful study of the herbarium materials and literature supports the recognition of the two new species. Detailed descriptions, line drawings, color plates, chromsome data, foliar SEM observations and comparisons with phenetically similar species are provided to aid in identification.

  2. Fulltext Phylogenetic analyses of Begonia sect. Coelocentrum and allied limestone species of China shed light on the evolution of Sino-Vietnamese karst flora
    Chung KF, Leong WC, Rubite RR, Repin R, Kiew R, Liu Y, et al.
    Bot Stud, 2014 Dec;55(1):1.
    PMID: 28510906 DOI: 10.1186/1999-3110-55-1
    BACKGROUND: The picturesque limestone karsts across the Sino-Vietnamese border are renowned biodiversity hotspot, distinguished for extremely high endemism of calciphilous plants restricted to caves and cave-like microhabitats that have functioned as biological refugia on the otherwise harsh habitats. To understand evolutionary mechanisms underlying the splendid limestone flora, dated phylogeny is reconstructed for Asian Begonia, a species-rich genus on limestone substrates represented by no less than 60 species in southern China, using DNA sequences of nrITS and chloroplast rpL16 intron. The sampling includes 94 Begonia species encompassing most major Asian clades with a special emphasized on Chinese species.

    RESULTS: Except for two tuberous deciduous species and a species with upright stems, a majority of Sino-Vietnamese limestone Begonia (SVLB), including sect. Coelocentrum (19 species sampled) and five species of sect. Diploclinium, Leprosae, and Petermannia, are rhizomatous and grouped in a strongly supported and yet internally poorly resolved clade (Clade SVLB), suggesting a single evolutionary origin of the adaptation to limestone substrates by rhizomatous species, subsequent species radiation, and a strong tendency to retain their ancestral niche. Divergence-time estimates indicate a late Miocene diversification of Clade SVLB, coinciding with the onset of the East Asian monsoon and the period of extensive karstification in the area.

    CONCLUSIONS: Based on our phylogenetic study, Begonia sect. Coelocentrum is recircumscribed and expanded to include other members of the Clade SVLB (sect. Diploclinium: B. cavaleriei, B. pulvinifera, and B. wangii; sect. Leprosae: B. cylindrica and B. leprosa; sect. Petermannia: B. sinofloribunda). Because species of Clade SVLB have strong niche conservatism to retain in their ancestral habitats in cave-like microhabitats and Begonia are generally poor dispersers prone to diversify allopatrically, we propose that extensive and continuous karstification of the Sino-Vietnamese limestone region facilitated by the onset of East Asian monsoon since the late Miocene has been the major driving force for species accumulation via geographic isolation in Clade SVLB. Morphologically species of Clade SVLB differ mainly in vegetative traits without apparent adaptive value, suggesting that limestone Begonia radiation is better characterized as non-adaptive, an underappreciated speciation mode crucial for rapid species accumulations in organisms of low vagility and strong niche conservatism.

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