A new species in Begonia sect. Diploclinium (Begoniaceae) from Guangxi, South China.

Although Guangxi represents one of the distribution centres of begonias in China, the sect. Diploclinium (Wright) A. DC is not well documented herein. In this article, we illustrate a new species belonging to this section, Begoniafangchengensis Y.N.Huang, X.X. Feng & R.K.Li, which has been discovered in southern Guangxi. Begoniafangchengensis mostly resembles B.rotundilimba in elliptic leaf blade, palmate veins, dichasial cyme, three styles, axile placentation, and unequally 3-winged capsule. On the other hand, B.fangchengensis is characterized by creeping rhizome, pilose stipule, red and densely pilose petiole, pubescent leaf blade and pilose inflorescence bract, sparsely pilose ovary and the zygomorphic androecium, differing from the erect stem at anthesis, the green and densely villous petiole, the glabrous stipule, leaf blade, inflorescence bract, ovary and actinomorphic androecium in B.rotundilimba. Considering its small population size and narrow distribution, its conservation status is categorized as 'Endangered (D)' according to the IUCN Red List Categories and Criteria.