Spiny rats of the genus Clyomys Thomas, 1916, include 2 recognized species both described on the basis of a small number of specimens, C. laticeps (Thomas, 1909) comprised of the nominotypical form and subspecies C. laticeps whartoni Moojen, 1952, and C. bishopi Avila-Pires and Wutke, 1981. Univariate and multivariate analyses of craniodental measurements obtained from 78 adult specimens from 8 pooled geographic samples representative of the distributional range of Clyomys structured the samples morphometrically into 2 geographic groups, which do not correspond to the taxonomic units postulated in previous studies. These morphometric groups were checked against data on qualitative skull morphology and pelage coloration from 128 specimens in a search for patterns supporting the taxonomic recognition of the morphometric groups revealed. The morphometric and qualitative analyses do not corroborate the current taxonomic framework of the genus Clyomys, and indicate that C. bishopi is a junior synonym of C. laticeps.