Abstract
Didymodon hengduanensis is described as a new species from the Hengduan Mountains in the provinces of Sichuan and Yunnan, China. It is characterized mainly by its lanceolate to ovate-lanceolate and appressed-incurved leaves when dry, acute leaf apices, recurved to revolute margins, the yellowish color in KOH, percurrent to subpercurrent costa, and marginal basal cells forming a distinctly differentiated area of smooth and transversely thick-walled cells. Drawings and light microscope photographs of the new species are provided. The principal characters that separate it from the most similar species are discussed.