Abrocoma bennettii, Waterhouse, 1837

Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Abrocomidae, Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona: Lynx Edicions, pp. 488-497 : 496

4.

Bennett's Chinchilla Rat

Abrocoma bennettii

French: Abrocome de Bennett / German: Chile-Chinchillaratte / Spanish: Rata chinchilla de Bennett

Other common names: Chilean Chinchilla Rat

Taxonomy. Abrocoma bennettii Waterhouse, 1837 ,

“ Chile.” Modified by G. R. Water house in 1839 based on C. Darwin’s restriction of “near old village of Aconcagua [= Plaza Vieja, ca. 5 km W Los Andes], Valparaiso, Chile.”

Two subspecies are recognized.

Subspecies and Distribution.

A.b.bennettiiWaterhouse,1837—CChile(Valparaiso,Santiago,andO'Higgins).

A. b. murrayi Wolffsohn, 1916 — N Chile (Antofagasta, Atacama, and Coquimbo).

Descriptive notes. Head—body 170-233 mm,tail 130-178 mm, ear 28-35 mm, hindfoot 31-40 mm; weight 150-307 g. Bennett's Chinchilla Ratis the largest species of Abrocoma . It is dark grayish brown above, with paler sides; venter is dark overall, with dark gray hairs washed with pale gray. Tail is covered with short hairs, not tufted at tip; it is dark brown above and below or with its basal one-halfslightly paler; and it is relatively long for the family (74-88% of head-body length). Feet are gray above and have blackish soles. Condylo-basal length of skull is 42-48 mm. Bennett's Chinchilla Rat has 17 pairs of ribs, more than found in other rodent species. All species of Abrocoma have small claws on forefeet and hindfeet. The subspecies murrayi is paler, with longer fur and a longertail than those of the nominate bennett.

Habitat. Sandy soils in densely vegetated Matorral (Mediterranean climate) scrub and arid thornscrub, with deciduous and evergreen shrubs and understory herbs in western Chilean lowlands, and rocky cactus shrublands with bromeliads and Euphorbia lactiflua ( Euphorbiaceae ) in arid coastal Chile. Habitat has been characterized by the Porlieria chilensis— Proustia pungens— Adesmia bedwellii association. Bennett's Chinchilla Rats have the largest elevational range of any species of Abrocomidae : from sea level to 2000 m in coastal canyons of the Andes. It is the only lowland species in the family, and the only species on the western side of the Andes. Unlike some other members of Abrocoma , Bennett's Chinchilla Rat is not an obligate of rocky outcrops.

Food and Feeding. Bennett's Chinchilla Rat is apparently a specialized herbivore that feeds chiefly on leaves and stems of one or a few plant taxa at a time, including Chenopodium petiolare ( Chenopodiaceae ), Acacia caven ( Fabaceae ), grasses, forbs, and seeds. It is scansorial and climbsto feed on foliage. One population fed on grasses and forbs in wet months (July-November) and chiefly on foliage of A. caven and Lithraea caustica ( Anacardiaceae ), supplemented by grasses and forbs, during drier months. Charles Darwin collected the holotype and elsewhere saw two Bennett's Chinchilla Rats climbing an Acacia tree, so he rightly surmised that it was semi-arboreal.

Breeding. Litter size of Bennett's Chinchilla Rat is 1-6 young. Populations can vary from c.15 ind/ha in El Nino years to less than 1 ind/ha in post-El Nino years. Within years, populations are small in austral winter and largest in summer. Pregnancy occurs in June-July. In August, a female was observed with two young. Sex ratio does not differ from 1:1.

Activity patterns. There is no specific information available for this species, but Bennett’s Chinchilla Rat is probably nocturnal, with some early morning activity.

Movements, Home range and Social organization. More than one Bennett's Chinchilla Rat will use the same burrow system, so they might be colonial. It shares its habitat with the Degu ( Octodon degus). They will simultaneously use the same burrow system, and lactating females and young of both species were found in a single system, with young even sharing the same nests. No specific data are available on movements, home range, or social behavior.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Bennett's Chinchilla Rat is protected in the 10,000ha Bosque FrayJorge National Park, and several other parks are within its geographical distribution. It frequently occurs in degraded, overgrazed grassland, whereit feeds on invasive plants avoided by cattle, so itis probably not threatened by human disturbance.

Bibliography. Fulk (1976), Guzman & Sielfeld (2011), Iriarte et al. (1989), Meserve (1981), Meserve, Martin & Rodriguez (1983), Meserve, Milstead et al. (1999), Valladares & Campos (2012), Waterhouse (1839a).

Figures

1. Ashaninka Inca Rat (Cuscomys ashaninka), 2. Machu Picchu Inca Rat (Cuscomys oblativus), 3. Bolivian Chinchilla Rat (Abrocoma boliviensis), 4. Bennett's Chinchilla Rat (Abrocoma bennettn), 5. Ashy Chinchilla Rat (Abrocoma cinerea), 6. Budin’s Chinchilla Rat (Abrocoma budini), 7. Famatina Chinchilla Rat (Abrocoma famatina), 8. Sierra del Tontal Chinchilla Rat (Abrocoma schistacea), 9. Uspallata Chinchilla Rat (Abrocoma uspallata), 10. Mendozan Chinchilla Rat (Abrocoma vaccarum)

Subspecies and Distribution. A.b.bennettiiWaterhouse,1837—CChile(Valparaiso,Santiago,andO'Higgins). A. b. murrayi Wolffsohn, 1916 — N Chile (Antofagasta, Atacama, and Coquimbo).