Viscacha rat

Other species may be referred to as a viscacha rat. See Octodontidae for a list of other rodents with a similar name.

Viscacha rat
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Octodontidae
Genus:	Octomys Thomas, 1920
Species:	O. mimax
Binomial name
Octomys mimax Thomas, 1920

The viscacha rat (Octomys mimax), or mountain viscacha rat, is a species of rodent in the family Octodontidae.^[2] It is endemic to Chile^{[citation needed]} and Argentina.

It is the only living species within the genus Octomys.^[3] This diploid genus (2n = 56) may be ancestral to the two unusual tetraploid species Tympanoctomys barrerae and Pipanacoctomys aureus.^[4]

Description

The viscacha rat is a rat-like animal with a head-body length of 11 to 18 centimetres (4.3 to 7.1 in) and weighing from 85 to 121 grams (3.0 to 4.3 oz). The feet are relatively long, while the tail measures 12 to 16 centimetres (4.7 to 6.3 in). It has light brown fur with white underparts and a bushy tail.^[3]

Unusual features of the viscacha rat include greatly enlarged auditory bullae, and the presence of numerous whiskers on the roof of the mouth behind the incisor teeth. The exact function of the whiskers is unclear, but they may enable the animal to sense the position of food inside the mouth.^[5]

Distribution and habitat

Viscacha rats are found only in the Monte Desert region of northwestern Argentina,^[1] specifically in the provinces of Catamarca, La Rioja, San Luis, San Juan, and possibly Mendoza. They inhabit rocky desert and semidesert environments up to 800 metres (2,600 ft) above sea level.^[3]

Behaviour

Viscacha rats are nocturnal and solitary, spending the day sheltering in rock crevices. Although it does not construct burrows, it may place pieces of cactus close to crevice entrances to help protect against predators.^[3] Individuals occupy large home ranges of around 12,300 square metres (3.0 acres), often overlapping with those of their neighbours.^[6] They are herbivorous, feeding on the leaves and seeds of shrubland vegetation. During the dry season, their diet consists largely of the leaves of Prosopis trees, supplemented by caperbushes and alkaliweeds. During the wet season, they eat more seeds and fruit, including those from plants such as Maytenus and boxthorn shrubs.^[3]

References

1. ^ ^{a b} Lessa, E., Ojeda, R. & Bidau, C. (2008). Octomys mimax. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 5 January 2009.
2. ^ Woods, Charles A.; Kilpatrick, C. William (16 November 2005). "Infraorder Hystricognathi (pp. 1538-1600)". In Wilson, Don E., and Reeder, DeeAnn M., eds. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Baltimore: Johns Hopkins University Press, 2 vols. (2142 pp.). pp. 1572. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=13400379. 
3. ^ ^{a b c d e} Sobrero, R., et al. (2010). "Octomys mimax (Rodentia: Octodontidae)". Mammalian Species 42 (1): 49–57. doi:10.1644/853.1. http://www.asmjournals.org/doi/full/10.1644/853.1. 
4. ^ Gallardo, M.H. (2006). "Molecular cytogenetics and allotetraploidy in the red vizcacha rat, Tympanoctomys barrerae (Rodentia, Octodontidae)"]. Genomics 88 (2): 214–221. doi:10.1016/j.ygeno.2006.02.010. PMID 16580173. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WG1-4JKYTJP-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a18e9e7ecd4f6082c8579d751043661d. 
5. ^ Berman, S.L. (2003). "A desert octodontid rodent, Tympanoctomys barrerae, uses modified hairs for stripping epidermal tissue from leaves of halophytic plants". Journal of Morphology 257 (1): 53–61. doi:10.1002/jmor.10115. 
6. ^ Ebensperger, L.A. et al. (2008). "Activity, range areas, and nesting patterns in the viscacha rat, Octomys mimax". Journal of Arid Environments 72 (7): 1174–1183. doi:10.1016/j.jaridenv.2008.02.003. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WH9-4S4J6MJ-1&_user=10&_coverDate=07%2F31%2F2008&_rdoc=5&_fmt=high&_orig=browse&_origin=browse&_zone=rslt_list_item&_srch=doc-info(%23toc%236845%232008%23999279992%23690558%23FLA%23display%23Volume)&_cdi=6845&_sort=d&_docanchor=&_ct=23&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=ce0cea5dec0f87dcba01b803dbd37b09&searchtype=a. 

• Gallardo, M.H.; Kausel, G.; Jiménez, A.; Bacquet, C.; González, C.; Figueroa, J.; Köhler, N.; Ojeda, R. (2004), "Whole-genome duplications in South American desert rodents (Octodontidae)", Biological Journal of the Linnean Society 82: 443–451, doi:10.1111/j.1095-8312.2004.00331.x. 
• Mares, M. A.; Braun, J. K.; Barquez, R. M.; Díaz, M. M. 2000. Two new genera and species of halophytic desert mammals from isolated salt flats in Argentina. Occasional Papers, Museum of Texas Tech University 203:i+1-27.

External links

• Data related to Octomys mimax at Wikispecies