Ruth Kiew

Phylogenetic analyses of Begonia sect. Coelocentrum and allied limestone species of China shed light on the evolution of Sino-Vietnamese karst flora

BackgroundThe 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.ResultsExcept 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.ConclusionsBased 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.

Two new Phlegmariurus species (Lycopodiaceae) and one new combination from Peninsular Malaysia

Abstract Two new species, Phlegmariurus iminii Kiew (Lycopodiaceae) from limestone karst and P. monticola Kiew from montane habitats, are described from Peninsular Malaysia and a new combination is made for Phlegmariurus pinifolius (Trevis.) Kiew. Phlegmariurus iminii, known from a single hill threatened by quarrying, is Critically Endangered; while P. monticola and P. pinifolius that are relatively widespread are of Least Concern.

Checklist of vascular plants from Batu Caves, Selangor, Malaysia

The vascular plant flora of Batu Caves, a tower karst limestone formation, includes 269 species; 51 species (19%) are Peninsular Malaysian endemics and 80 species (30%) are calciphiles of which 56 (21%) are obligate calciphiles and 26 species are obligate calciphiles endemic to Peninsular Malaysia. Four taxa are endemic to Batu Caves itself. That Batu Caves harbours a sizeable fraction (21.4%) of Peninsular Malaysia’s limestone flora underlines the need for detailed checklists of each and every limestone hill to enable adequate planning of conservation programmes to support biodiversity. Because botanical collecting began in the 1890s, Batu Caves is important as the type locality of 24 plant species. Land-use pressures have over time eliminated the surrounding native vegetation, leaving the flora vulnerable to aggressive weedy and alien species. Although designated as a Public Recreation Area, its protection status needs to be enforced and the boundaries clearly marked.

Taxonomic status of Begonia promethea (sect. Petermannia, Begoniaceae) in Borneo

The rediscovery of Begonia promethea Ridl. for the first time since its description in 1906 led to the discovery that the later described B. beccarii Warb. is synonymous with it and that it belongs in Begonia sect. Petermannia. It is a rare, endangered species known only from three localities, two locations from the Kuching Division, Sarawak, Malaysia and another one from West Kalimantan, Indonesia. A detailed, illustrated description and a distribution map of Begonia promethea are provided. We suggest an IUCN conservation category of EN B2ab(iii). Lectotypes for both names are designated.

Vatica najibiana (Dipterocarpaceae), a new species from limestone in Peninsular Malaysia

Abstract Vatica najibiana Ummul-Nazrah (Dipterocarpaceae), from the Relai Forest Reserve, Gua Musang, Kelantan and Gua Tanggang, Merapoh, Pahang, is described and illustrated. This species is Endangered and known from small populations restricted to two isolated karst limestone hills. The type locality, Relai Forest Reserve limestone, is currently under threat from encroaching oil palm plantations and ongoing logging, which, if it continues, will threaten the Kelantan population with extinction. The morphology of V. najibiana and the similar V. odorata subsp. odorata and V. harmandiana is compared.

Asplenium merapohense (Aspleniaceae), a new species from the Peninsular Malaysia

Abstract A new species of Asplenium is described from two collections made on limestone hills in Peninsular Malaysia. Conspicuous by its extremely narrow pinnae, it is probably allied to A. salignum but differs in sufficient characters (scale size, size and shape of lamina, venation and sorus length, position and orientation) to be a species in its own right.

The Calcarea group of Begonia (Begoniaceae) from Borneo, including four new species from Sarawak

Four new species, Begonia kanaensis Kiew & C.Y.Ling, Begonia lingiae S.Julia, Begonia rubrotepala S.Julia and Begonia sadirensis Kiew & S.Julia are described from Sarawak, Borneo. Notes on habitat, distribution and additional specimens examined for Begonia calcarea and B. sabahensis are also provided. A key to the species in the ‘calcarea group’ is provided. The status of the ‘calcarea group’ as belonging to Begonia sect. Diploclinium or to a new section is discussed. A provisional conservation status is assigned to each species.