Begonia bamaensis (sect. Coelocentrum, Begoniaceae), a new species from limestone areas in Guangxi, China

Begonia bamaensis Yan Liu & C.-I Peng, a new species of sect. Coelocentrum from Guangxi Zhuangzu Autonomous Region, China, is described and illustrated. Its somatic chromosome number (2n = 30) is here reported. Begonia bamaensis is somewhat similar to B. cirrosa L.B. Smith & D.C. Wasshausen, differing in the leaves adaxially densely setulose or hispidulous and adorned with white bands or white patches between major veins; stipules abaxially glabrous or with few hairs along midrib; peduncle pilose or sparsely so; staminate flower with outer tepals 7-14.5 x 7-13.5 mm; ovary whitish or reddish pilose; capsule 7-12 mm long, and abaxial wing of capsule distinctly curved on one side. SEM micrographs of leaves of B. bamaensis revealed prominently elevated stomata complex, which is unique for the genus Begonia. Like many congeners in sect. Coelocentrum, B. bamaensis is a handsome species with variegated leaves. It has a restricted distribution, currently known only from two nearby karst eaves in western Guangxi.