Family Ctenomyidae Lesson, 1842 . Nouv. Tabi. Règne Animal., Mamm., p. 105.

COMMENTS: This assemblage of 56 named species is in need of revision. The species are variable in chromosome number, but fairly uniform in morphology, suggesting that the major radiation of species was in the Pleistocene (Roig and Reig, 1969:666; Reig et al. (19906:89). Ctenomys is most closely allied to the octodontid Octodontomys . Whether the group should be recognized as a subfamily (Ctenomyinae, Reig, 1958), or as a family is debated. Although the designation of subfamily within the Octodontidae best reflects the evolutionary history of the group, it is more common to treat the group as a distinct family specialized for fossorial life. Glanz and Anderson (1990) gave a cladogram and list of synapomorphies for the Ctenomyidae . Here 39 species are recognized. Reig (1986:408) stated that his analysis indicated there may be 44 valid species. See Reig et al. (19906) for an overview of ctenomyid taxonomy, and Cook et al. (1990:22-24) for a discussion of the possible significance of the extensive chromosomal variation in Ctenomys and octodontids (2n=10-102), which is nearly as great as the known variation for all mammals.