Didymodon sicculus sp. nov. is described and illustrated from southeastern Spain where it occurs on saline and gypsiferous soils. The new species is similar in habit to D. luridus Spreng., but differs in having leaves with smaller upper cells, rectangular basal cells, margins recurved from near the apex to the base, and quite papillose laminal cells. For the last several years, we have been studying the bryophyte flora and vegetation of southeastern Spain, and many samples of a taxon macroscopi- cally similar to Didymodon luridus Spreng. were collected in the provinces of Alicante and Almeria. We have concluded that these samples correspond to an undescribed taxon. DIDYMODON SICCULUS Cano, Ros, Garcia-Zamora, & J. Guerra sp. nov. (FIG. 1-20) Species dignoscenda phyllidiis papillosis, quorum api- cales cellulae sunt 6-14 ipm latae, parietibus incrassatae atque nonumquam bistratae, cellulae autem basilares, longe rectangulae.