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

Begonia pulvinifera, a new species of sect. Diploclinium from limestone areas in southwestern Guangxi Zhuangzu Autonomous Region, China, is described and illustrated. This new species is unique in having pulvinate petioles, a feature not known in any other species of Begonia in China. Begonia pulvinifera is similar to B. wangii T. T. Yu, differing in the lower surface of the leaf being pale green; petiole with a reddish brown swollen base; tepals obtuse; tepals of staminate flowers 4; tepals of carpellate flowers 3 and ovary with axile placentation throughout. Begonia pulvinifera also resembles B. cavaleriei Lev., but is distinguishable by the narrower leaf, pulvinate petiole; stipules triangular with apex acuminate or cuspidate; and ovate bracts with apex acute or acuminate. Begonia pulvinifera is rare, currently known only from one population near the border of China and Vietnam.