Paraspidodera uncinata (Rudolphi, 1819) (Nematoda, Aspidoderidae), a parasite of Neotropical caviids and octodontids, is redescribed based on specimens from the caecum and large intestine of the subterranean rodent Ctenomys talarum Thomas, 1898 (Octodontidae). During 2002, a total of 3,899 nematodes was recovered from eighty one specimens of C. talarum (prevalence 93.8%, mean abundance 51.3) from Mar de Cobo, Buenos Aires Province, Argentina (37°58´S, 57°34´W). In spite of the long list of records of P. uncinata published since its original description in 1819, descriptions available in the literature are scattered and incomplete. Therefore, a number of diagnostic morphological and morphometric features that were omitted in previous descriptions of this species, are given. These are: variability in number and position of caudal papillae in males, presence of caudal papillae in females, as well as descriptions and measurements of corpus, bulb, pharynx, lateral alae, deirids, nerve ring, vagina and uterus. Location of labial papillae and the vulva as well as the length of the left and right spicules are also provided.