Scapteromys is a genus of South American rodents in the tribe Akodontini of family Cricetidae. Three species are known, found in northern Argentina, southern Brazil, Paraguay and Uruguay. They are as follows: \n* Argentine swamp rat (Scapteromys aquaticus) \n* Plateau swamp rat (Scapteromys meridionalis) \n* Waterhouse's swamp rat (Scapteromys tumidus) The three species differ in karyotype, with aquaticus having 2n = 32, tumidus 2n = 24 and meridionalis 2n = 34/36.