In a survey of mammals from Paraguay, 3 species, Artibeus lituratus, the great fruit-eating bat, Tolypeutes matacus, the southern 3-banded armadillo, and a Tolypeutes sp. were found to be infected with oligacanthorhynchid acanthocephalans. Artibeus lituratus harbored Neoncicola artibei n. sp., which differs from its congeners in the number and morphology of the hooks of the proboscis armature. The generic diagnosis of Neoncicola has been emended accordingly. Oligacanthorhynchus carinii Travassos, 1916 was found in T. matacus and an oligacanthorhynchid cystacanth in Tolypeutes sp. Previous arguments that the concept of Oligacanthorhynchus should be restricted to species from bird hosts and the concept of Hammaniella be reinstated for species infecting mammals could not be addressed using the data presently available.