Ophiorrhiza xinchengensis (Rubiaceae), a new species from Guangxi, China

Ophiorrhiza xinchengensis (Rubiaceae), a new species from the middle part of Guangxi, China, is described and illustrated on the basis of morphological evidence. This new species resembles Ophiorrhiza longanensis in its densely pubescent stems, linear stipules, terminal or upper axillary inflorescences, but it can be distinguished by its elliptic or oblanceolate leaf blade, base attenuate (vs. oval, ovate to broadly ovate, base cuneate), its 2–3 mm long stipules (vs. 3.8–6.5 mm long), its 3–5 mm long bracteoles (vs. 6–10 mm long) its 10–12 mm long corolla tubes (vs. 2–3 mm long) and its filaments adnate at the middle of corolla tube, styles 12–15 mm long (vs. adnate to the base of corolla tube and styles ca. 3 mm long). The new species is currently known from a single population with approximately 60–100 mature individuals. Following IUCN Criteria, it is provisionally assessed as Critically Endangered. Photographs, an illustration and a distribution map are also provided.