A new species of Cavia Pallas, 1766 (mammalia - Caviidae) is described on the basis of 20 skulls and 9 skins from an island of Moleques do Sul Archipelago (Santa Catarina State, southern Brazil), 14 km from the mainland. This species has size and coloration intermediates between C. aperea and C. magna. Cranially, it differs from the other Brazilian species of Cavia by demonstrating a flat sagittal crest, large ...