[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.

[5] The species is known from Catamarca Province of northwestern Argentina, where specimens are known only from the Salar de Pipanaco, a salt flat.

[6] The genus is named after the locale, with “octo” being a reference to the figure-eight ridge on its cheek tooth.

It is threatened by conversion of its very restricted habitat to agricultural use, for the growing of olives, and its population trend is downwards.