Spiradiclis liboensis L. Wu & W. J. Liu, a new species in tribe Ophiorrhizeae of Rubiaceae from limestone mountain areas of Guizhou, south-western China, is described and illustrated. It is similar to S. guangdongensis and S. jingxiensis, but differs from the latter two by the following traits: stipule triangular, inflorescence sessile or with peduncle up to 0.5 mm long, pedicel 0.8-2.2 mm long, corolla white, salverform, corolla tube 1.6-2.2 cm long, corolla tube of long-styled morph inside with a villous ring and stigmas positioned at the throat of the corolla tube. The conservation status is assessed as "Vulnerable" (VU) according to the IUCN Red List Categories and Criteria. [ABSTRACT FROM AUTHOR]