Isotrema haimingii, a new species of Aristolochiaceae from Dayaoshan Mountain of Guangxi, China

Isotrema haimingii Y.S. Huang & Yan Liu, a new species from Dayaoshan Mountain of Guangxi, China, is described and illustrated. It is morphologically most similar to I. championii and I. yachangense in the shape of leaf blade, lanceolate-ovate bracteoles, oblong anthers, 3-lobed gynostemium and ellipsoid capsules, but can be easily distinguished from them by length of the basal perianth tube, colour of calyx limb and the outside of perianth tube, surface texture of calyx limb and throat. Photos of this new species, as well as a table to distinguish it from other morphologically similar Isotrema species, are provided. The threatened status of the new species is also assessed.