Tympanoctomys kirchnerorum, Teta, Pardiñas, Sauthier & Gallardo, 2014

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Octodontidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 536-541 : 538

2.

Kirchners’ Viscacha Rat

Tympanoctomys kirchnerorum

French: Octodon des Kirchner / German: KirchnerViscacharatte / Spanish: Rata vizcacha de Patagonia

Taxonomy. Tympanoctomys kirchnerorum Teta et al, 2014 ,

“ Argentina, Province of Chubut, department of Gastre, 18 km NNE by road of Los Adobes , conjunction between Ruta Provincial 58 and Zanjon El Colorado (43°13'51.6", 68°38'49.1", 517m).”

This species is monotypic.

Distribution. S Argentina, known distribution limited to the type locality and surrounding areas in Chubut Province.

Descriptive notes. Head-body 111-136 mm, tail 111-120 mm, ear 14-15 mm, hindfoot 29-35 mm; weight 50-80 g. Kirchners’ Viscacha Rat is slightly smaller than the Red Viscacha Rat ( T. barrerae ). Its skull is more bowed in dorsal profile than the Red Viscacha Rat. Color of Kirchners’ Viscacha Rat is pale brown dorsally and whitish to white ventrally. Tail is relatively long (43-50% of head-body length), with a medium terminal brush. Short, thick, and whitish hairs cover forefeet and hindfeet. Oral bristle bundles are well developed. Kirchners’ Viscacha Rat has 2n = 102, similar to that of Red Viscacha Rat. Karyotype has 32 pairs of metacentric to submetecentric chromosomes and 18 pairs of subtelocentric chromosomes. Sex chromosomes could not be discriminated but probably resembled those of the Red Viscacha Rat. Sperm morphology of Kirchners’ Viscacha Rat is smaller in size but similar in shape to that of the Red Viscacha Rat.

Habitat. Sandy terrain in a general badland landscape within the Chuquiraga avellanedae ( Asteraceae ) steppe of the Patagonian Ecoregion at an elevation of 500 m. Burrows of Kirchners’ Viscacha Rat have typical semicircular entrances c.10 cm high, are well curved above and flat below, and are usually placed under Atriplex (Amaranthaceae) bushes. Plant cover near burrows is sparse, consisting mostly of low shrubs, such as Atriplex , C. avellanedae, Prosopis sp. and Prosopidastrum sp. (both Fabaceae ), and Schinus johnstonii ( Anacardiaceae ).

Food and Feeding. There is no specific information for this species, but Kirchners’ Viscacha Rat probably feeds mainly on halophytic vegetation (e.g. Atriplex ).

Breeding. There is no information available for this species.

Activity patterns. There is no specific information available for this species, but Kirchners’ Viscacha Rat is apparently nocturnal.

Movements, Home range and Social organization. There is no specific information available for this species, but Kirchners’ Viscacha Rat is probably solitary.

Status and Conservation. As a newly described species, Kirchners’ Viscacha Rat has not been assessed on The IUCN Red List. No information is available aboutits conservation status, but its very limited distribution (restricted to the type locality) together with its recent extirpation (Late Holocene) from the Chubut River Valley and potential impact of mining in central Patagonia suggest that Kirchners’ Viscacha Rat has a high risk of extinction in the short term.

Bibliography. Gallardo et al. (2009), Leon et al. (1998), Ojeda et al. (2007), Pardinas et al. (2012), Sauthier et al. (2009), Teta et al. (2014).

Figures

On following pages: 4. Chalchalero Viscacha Rat (Salinoctomys loschalchalerosorum); 5. Common Viscacha Rat (Octomys mimax); 6. Mountain Degu (Octodontomys gliroides); 7. Bridges's Degu (Octodon bridgesii); 8. Pacific Degu (Octodon pacificus); 9. Coastal Degu (Octodon lunatus); 10. Common Degu (Octodon degus); 11. Porter's Rock Rat (Aconaemys porteri); 12. Chilean Rock Rat (Aconaemys fuscus); 13. Sage’s Rock Rat (Aconaemys sage), 14. Coruro (Spalacopus cyanus).

Distribution. S Argentina, known distribution limited to the type locality and surrounding areas in Chubut Province.