Ornithological studies undertaken in certain sandy soil habitats of lowland northeastern Peru uncovered a previously undescribed species of Percnostola antbird. Elements of its morphology, vocalizations, and behavior indicate that it should be considered a well-differentiated species, closely related to P. rufifrons. We present a description of the new species; an analysis of how it differs from the four previously described subspecies of P. rufifrons; and a reconsideration of species limits within P. rufifrons, employing measures of morphology, vocalizations, and behavior. Under guidelines developed previously (Isler et al. 1998, 1999), vocal differences among the four subspecies (rufifrons, subcristata, minor, and jensoni) of P. rufifrons were insufficient to support considering them distinct species. However, differences in morphology among most of the four taxa were substantial, and we look forward to genetic studies of Percnostola and related groups. The localized and highly specialized habitat preferences of the new species cause grave concern for its conservation.