Didymodon edentulus J.A.Jimenez & M.J.Cano, is described and illustrated as a new Andean species from the Cordillera Occidental in north-central Peruvian departments of Ancash, La Libertad and Lima. It is characterized mainly by its appressed leaves when dry, plane margins above midleaf, smooth laminal cells, oblate and transversely thick-walled marginal basal cells, differentiated perichaetial leaves and gymnostomous capsules. Its distinction from, and relationships with some closely related species within the genus are discussed.