Abstract A new species of Oligancanthorhynchidae (Acanthocephala) Prosthenochis cerdocyonys n. sp. is described from 17 specimens collected from the small intestine of the crab-eating fox Cerdocyon thous Linnaeus, 1766 (Canidae: Carnivora) found in the Brazilian Pantanal Wetlands. The new species were studied using light and scanning electron microscopy. Characteristic features distinguishing the new species from others already described were presented, such as size of the body, the position of lemnisci, size of the eggs, host, and geographical distribution. Therefore, details of the body surface obtained by scanning electron microscopy, such as the presence of 2 lateral papillae in the proximal region of the proboscis, the presence of barbs in hooks, a robust and festooned collar, helped to identify the species. Until now, specimens of the genus Prosthenorchis were reported to parasitize Cerdocyon thous but had not been identified. Furthermore, the new species is the first to be recorded in C. thous found in the Pantanal Wetlands.