We analyzed phenotypic variation in white-eared Didelphis and its relevance to the current taxonomy of these opossums. On the basis of morphologic and morphometric data we show that the white-eared Didelphis can be split into 3 groups of populations referred to as albiventris, pernigra, and imperfecta. Morphologically, pernigra possesses a large, peg-like 3rd upper premolar (P3), whereas albiventris and imperfecta possess a small, non–peg-like P3. Also, albiventris has 88% of its specimens in the gray dorsal color phase, whereas the other 2 groups show similar percentages of specimens in the gray and black color phases. Morphometrically, pernigra is significantly larger (P < 0.05; analysis of variance) than the other 2 groups in most traits. Squared Mahalanobis distances among the 3 groups were found to be high, and discriminant analysis was successful in separating groups (99% of cases correctly classified). The congruence in variation of independent traits indicates genetic differentiation among populations. In addition, the sharp discontinuity observed between the parapatric albiventris and pernigra in Bolivia suggests that limited or no gene flow occurs between them. We conclude that the 3 groups analyzed here merit taxonomic recognition at the species level.