Atriotaenia sanmarci n. sp. (Cestoda: Anoplocephalidae) is described as a parasite of the Andean hog-nosed skunk, Conepatus chinga (Carnivora: Mephitidae), from Cusco, Per. The new species is primarily distinguished from related species by the distribution, and greater number, of testes, i.e., 194223 versus 4060 in Atriotaenia sandgroundi (Sandground, 1926) Baer, 1935, 4773 in Atriotaenia procyonis (Chandler, 1942) Spasskii, 1951, and 2184 in Atriotaenia incisa Railliet, 1899. Also, there are differences with respect to the larger dimensions of suckers (300371 m vs. 140 in A. sandgroundi, 83134 in A. procyonis, 70140 in A. incisa, and 155192 in Atriotaenia hastati Vaucher, 1982) and in the cirrus pouch length (204732 m vs. 90 in A. sandgroundi, 200220 in A. procyonis, 100180 in A. incisa, and 150205 in A. hastati). The new species differs from A. sandgroundi and A. hastati in having a larger body size (122133 mm vs. 10.6 and 10, respectively). This cestode is the fifth species of Atriotaenia Sandground, 1926. © 2012 American Society of Parasitologists.