Golden viscacha rat

The golden viscacha rat or golden vizcacha rat (Pipanacoctomys aureus) is the single species of the genus Pipanacoctomys of the rodent family Octodontidae.[2] It has 92 chromosomes and has been regarded as tetraploid (4x = 2n).[3] This octodontid and its sister-species, the plains viscacha rat (Tympanoctomys barrerae) (2n = 102), may have arisen from the diploid mountain viscacha rat (Octomys mimax),[3] (2x = 2n = 56) as a result of the doubling and subsequent loss of some chromosomes. However, some genetic studies have rejected any polyploidism in mammals as unlikely, and suggest that amplification and dispersion of repetitive sequences best explain the large genome size.[4]

Golden viscacha rat

Critically Endangered  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Octodontidae
Genus: Pipanacoctomys
Mares, Braun, Barquez, and Díaz, 2000
Species:
P. aureus
Binomial name
Pipanacoctomys aureus
Mares, Braun, Barquez, and Díaz, 2000

Description

The golden viscacha rat grows to a head-and-body length of about 170 millimetres (7 in) with a tufted tail of about 140 millimetres (6 in). The dorsal fur is golden-blond and the underparts are white.[5]

Distribution and habitat

The species is known from Catamarca Province of northwestern Argentina, where specimens are known only from the Salar de Pipanaco, a salt flat. This habitat consists largely of low, salt-loving shrubs, and the soil consists of sand with high levels of salt. It feeds on the halophytic plants growing there.[6] The genus is named after the locale, with “octo” being a reference to the figure-eight ridge on its cheek tooth.

Status

The golden viscacha rat is only found within a very restricted area totalling less than 100 square kilometres (39 sq mi) and it actually occupies only about one tenth of that area. It lives among the salt-loving plants that live between the salt pans and the desert. It is threatened by conversion of its very restricted habitat to agricultural use, for the growing of olives, and its population trend is downwards. The International Union for Conservation of Nature has rated its conservation status as "critically endangered".[1]

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References
  1. Roach, N. (2016). "Tympanoctomys aureus". IUCN Red List of Threatened Species. 2016: e.T136557A78324400. Retrieved 30 January 2020.CS1 maint: ref=harv (link)
  2. Woods, C.A.; Kilpatrick, C.W. (2005). "Infraorder Hystricognathi". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 1572–1573. ISBN 978-0-8018-8221-0. OCLC 62265494.
  3. Gallardo, M. H. et al. (2004). Whole-genome duplications in South American desert rodents (Octodontidae) Archived 2012-04-25 at the Wayback Machine. Biological Journal of the Linnean Society, 82, 443-451.
  4. Svartman, Marta; Stone, Gary; Stanyon, Roscoe (2005). "Molecular cytogenetics discards polyploidy in mammals". Genomics. 85 (4): 425–30. doi:10.1016/j.ygeno.2004.12.004. PMID 15780745.
  5. 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" (PDF). Occasional Papers, Museum of Texas Tech University. 203: 1–27. Archived from the original (PDF) on 2012-02-17. Retrieved 2011-03-29.
  6. Mares, Michael A. (1 November 2003). "Desert dreams: seeking the secret mammals of the salt pans - Naturalist at Large" (PDF). Natural History: 29–34.
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