Abstract

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, Begonia fangchengensis Y.N.Huang, X.X. Feng & R.K.Li, which has been discovered in southern Guangxi. Begonia fangchengensis 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.

Key words: Limestone karst, morphology, new taxon, south China, taxonomy

Begonia fangchengensis  A habitat B stipule C, D bracts of inflorescences E, F front and back view of staminate flower G androecium H stamens I, J pistillate flower with 3 or 5 tepals K styles L styles and ovary M–Q ovary section from upper to lower positions. Drawn by Yunxiao Liu

Habitat and morphology of Begonia fangchengensis A habitat B flowering plant C creeping rhizome D stipules E leaf blade (adaxial) F, G leaf blade (abaxial) H juvenile leaf I inflorescence J bracts K, L front and side views of staminate flower M, N front and side views of androecium O stamens P pistillate flower with 3 tepals Q, R, S pistillate flower with 5 tepals T stigmas and ovary U ovary sections from upper to lower positions V capsule (Photos by Z.X. Liu).