Abstract: Isometrum wanshanense S. Z. He, a new species of the Gesneriaceae from Wanshan County, Guizhou, China, is described and illustrated. This species is related to I. villosum K. Y. Pan in having peduncle and pedicel subglabrous to brown villous, corolla thinly cylindric, purple, not contracted at the throat, adaxial lip longer than abaxial one, and stamens and pistil glabrous, but differs by having leaves petiolate, petiole 0.4-1.4 cm long, leaf blade oblanceolate, 1.5-4×0.5-1.6 cm, cymes 1-4-flowered, calyx segments glabrous outside or sparsely brown villous near the apex, and thecae confluent. The genus is endemic to China, and is recorded in Guizhou Province for the first time.

Key words: Isometrum, Isometrum wanshanense S. Z. He, Gesneriaceae, new species, Guizhou, China