A new species, Cyphostemma dehongense, is described from Dehong, Yunnan, China, and C. auriculatum is newly recorded from Vietnam. These are the first records of the genus Cyphostemma from the two countries, extending both the easternmost and northernmost distribution limit of Cyphostemma. Through field explorations over two years, we discovered four populations of C. dehongense and collected specimens of the species with both flowers and fruits. Cyphostemma dehongense and C. auriculatum are morphologically similar, but differ in ovary size, style length, and fruit size. In addition to morphological comparisons, molecular data were used to determine the phylogenetic position of the new species and the newly recorded taxon. Ten nucleotide variation sites were detected between C. dehongense and C. auriculatum based on five chloroplast loci (atpB-rbcL, rps16, trnC-petN, trnH-psbA, and trnL-F) and the nuclear ribosomal internal transcribed spacer (ITS). An identification key is provided for the three species of Cyphostemma from Asia.
