Based on morphological and molecular evidence, a new combination, Syntrichia kingii, is proposed for Tortula kingii, an Andean taxon previously treated as conspecific with S. percarnosa. Tortula nigra is also synonymized with S. kingii. Maximum parsimony and Bayesian analyses of chloroplast DNA sequences (trnL-trnF and trnG regions) were undertaken to assess the affinities between these cucullate-leaved species. Syntrichia kingii is described, illustrated, and its distribution mapped. The known range of this species is extended in the Neotropics to Guatemala, Mexico, and Venezuela. Diagnostic characters, microphotographs, and a morphological comparison with S. percarnosa are provided. Syntrichia percarnosa is excluded from the Mexican moss flora.