
A new species in Rubiaceae, Ophiorrhiza xishuiensis, is described from China. The new species is endemic to the Danxia landform at the juncture of Guizhou Province, Sichuan Province, and Chongqing City. It is a herb with a 1–7 cm long rooting stem, 3–11 nodes, and most leaves arranged in markedly unequal pairs. It has a somewhat inequilateral leaf blade base, a congested-cymose inflorescence, and well-developed bracteoles. We investigated two populations in Guizhou, China. The new taxon has been collected or photographed by others in Sichuan and Chongqing, China, and misidentified as O. japonica, O. umbricola, O. cantonensis, or O. chinensis. An identification key to O. xishuiensis and morphologically similar species is provided.
