Notes on Begonia (sect. Coelocentrum, Begoniaceae) from Guangxi, China, with the report of two new species

Begonia curvicarpa and B. luochengensis, two new species of sect. Coelocentrum from the karst area in northern Guangxi Zhuangzu Autonomous Region, China are described and illustrated. Their somatic chromosome numbers, both 2n = 30, are reported. Begonia curvicarpa resembles B. porteri, from which it differs in having longer (1.5-5.5 cm vs. 0.8-1.7 cm) internodes on the rhizome, fewer hairs on upper leaf surface, and remarkably curved capsules. Begonia luochengensis is similar to B. luzhaiensis, but differs from the latter in having ovate (vs. orbicular to broadly ovate) leaves with a characteristic white band along midrib. Begonia yishanensis is treated as a synonym of B. porteri, and B. zhangii is treated as a synonym of B. daxinensis.