Temporal range: Late Miocene–Recent
Octodontidae is a family of rodents, restricted to southwestern South America. Thirteen species of octodontid are recognised, arranged in nine genera. The best known species is the degu, Octodon degus.
Octodontids are medium-sized rodents, ranging from 12 to 20 cm (4.7 to 7.9 in) in body length. They have long, silky, fur, which is typically brownish in color, and often paler on the underside. The name 'octodont' derives from the wear pattern of their teeth, which resembles a figure 8. Most are nocturnal, social, burrowing animals, though the degu is largely diurnal. They are herbivorous, eating tubers, bulbs, and cactuses.
Some authors have suggested that the octodontids should be reclassified in the order Lagomorpha, but this has not been supported by further analyses (e.g. Opazo, 2005). Older literature includes the tuco-tucos in the family, as the subfamily Ctenomyinae, but these animals are normally now treated as a separate family, Ctenomyidae. Two of the genera now included in this family, Salinoctomys and Pipanacoctomys, have only recently been described. There is some evidence that evolution within the family may have resulted from polyploidy. The red viscacha rat, Tympanoctomys barrerae, is tetraploid, with 102 chromosomes, and the recently described golden viscacha rat Pipanacoctomys aureus has 92.
Members of the genus Aconaemys are referred to as rock rats, and members of genus Octodon are all called degus, though the name degu on its own implies O. degu. The single member of Spalacopus, S. cyanus, is called the coruro. Members of the other genera are called viscacha rats: note, however, that viscachas are not octodontids - they are members of the chinchilla family Chinchillidae.
List of species
Genus Aconaemys Ameghino, 1891 (Andean rock rats).
- Species Aconaemys fuscus (Waterhouse, 1842) (Chilean rock rat). Andes of Chile and Argentina.
- Species Aconaemys porteri Thomas, 1917. (Porter's rock rat) Andes of Chile and Argentina.
- Species Aconaemys sagei (Pearson, 1984) (Sage's rock rat). Andes of Chile and Argentina.
Genus Octodon Bennett, 1832 (Degus).
- Species Octodon bridgesi Waterhouse, 1844 (Bridges' degu). Andes of Chile and Argentina.
- Species Octodon degus (Molina, 1782) (Degu). Western Chile.
- Species Octodon lunatus Osgood, 1943 (Moon-toothed degu). Western Chile.
- Species Octodon pacificus Hutterer, 1994 (Isla Mocha degu). Isla Mocha, off western Chile.
Genus Octodontomys Palmer, 1903.
- Species Octodontomys gliroides Gervais & D'Orbigny, 1844. (Mountain degu) Andes of northwestern Argentina, extreme northeastern Chile and western Bolivia.
Genus Octomys Thomas, 1920.
- Species Octomys mimax Thomas, 1920 (Mountain viscacha rat). Andes of Argentina.
Genus Pipanacoctomys Mares et al., 2000.
- Species P. aureus Mares et al., 2000 (Golden viscacha rat). Catamarca Prov., Argentina.
Genus Salinoctomys Mares et al., 2000.
- Species Salinoctomys loschalchalerosorum Mares et al., 2000 (Chalchalero viscacha rat). La Rioja Prov., Argentina.
Genus Spalacopus Wagler, 1832.
- Species Spalacopus cyanus (Molina, 1782) (Coruro). Western Chile.
Genus Tympanoctomys Yepes, 1942.
- Species Tympanoctomys barrerae (Lawrence, 1941) (Plains Viscacha Rat or Red viscacha rat). Scattered localities in western Argentina.
- Gallardo, M. H. et al.. (2004). Whole-genome duplications in South American desert rodents (Octodontidae). Biological Journal of the Linnean Society, 82, 443-451.
- Opazo, J. C. (2005). A molecular timescale for caviomorph rodents (Mammalia, Hystricognathi). Molecular Phylogenetics and Evolution, 37, 932-937.
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