Sierra del Tontal chinchilla rat explained

The Sierra del Tontal chinchilla rat (Abrocoma shistacea) is a species of chinchilla rat. Found only in Argentina, this species was once thought to be part of Abrocoma cinerea. In 2002, Braun and Mares from the University of Oklahoma confirmed it to be a separate species.^[1]

Description

The Sierra del Tontal chinchilla rat is a smallish, rat-like animal, with a head-body length of about 16cm (06inches), a tail about 10cm (00inches) long, and an average adult body weight of 174g. It has drab greyish fur, which is paler on the underside, and has a faint stripe of darker fur running down the middle of the back and along the upper surface of the tail. The upper surfaces of the feet are covered with white fur, and there is also a distinct patch of white fur on the chest, covering a scent gland.^[2] The lower surfaces of the feet have thick pads with leathery tubercles, which help the animal gain traction on bare rock.^[3]

Distribution and habitat

The species is known only from the Sierra del Tontal, in San Juan Province of north-western Argentina. The region is a rocky desert, dominated by shrubs and cacti, and the animal has been found between elevations of 1100mand2900mm (3,600feetand9,500feetm).^[1] No subspecies are recognised.

Biology and behaviour

The Sierra del Tontal chinchilla rat is thought to be primarily diurnal, being most active in the early morning, and live in groups of three to four individuals. They shelter in rocky crevices on east-facing slopes, and deposit their faeces in large latrines.^[4] They are herbivorous, and feed almost entirely on jarilla bushes, being resistant to the toxic compounds produced by those plants.^[2] Like the related Punta de Vacas chinchilla rat,^[5] the Sierra del Tontal species has a pair of "false teeth" in the mid-line of its palate, which apparently help with food manipulation and are aided by a horny pad on the tongue. These false teeth arise from the epithelium of the mouth, and are not preserved in skeletal remains of the animal.^[2]

Nothing is known of their reproduction, although other chinchilla rats give birth to litters of up to six pups twice a year.^[2]

Notes and References

1. Systematics of the Abrocoma cinerea species complex (Rodentia: Abrocomidae), with a description of a new species of Abrocoma. Braun, Janet K.. Mares, Michael A. . February 2002. Journal of Mammalogy. 83. 1. 1–19. 10.1644/1545-1542(2002)083<0001:SOTACS>2.0.CO;2. free.
2. Taraborelli, P.A. . August 2015 . Abrocoma schistacea (Rodentia: Abrocomidae) . Mammalian Species . 47 . 921 . 45–50 . 10.1093/mspecies/sev004. etal. free . 11336/45542 . free .
3. Mares, M.A. . Lacher, T.E. . Hugh H . Genoways . amp . 1987 . Ecological, morphological and behavioral convergence in rock-dwelling mammals . Current Mammalogy . 1 . 307–348 . 10.1007/978-1-4757-9909-5. 978-1-4757-9911-8 . 44621903 .
4. Taraborelli, P. . June 2011 . New eco-morphological-behavioural approach of the chinchilla rats in the pre-Andean foothills of the Monte Desert (Argentina) . Journal of Natural History . 45 . 27–28 . 1745–1758 . 10.1080/00222933.2011.560725. 85741987 . etal.
5. Braun, J.K. . Mares, M.A. . amp . August 1996 . Unusual Morphological and Behavioral Traits in Abrocoma (Rodentia: Abrocomidae) from Argentina . Journal of Mammalogy . 77 . 3 . 891–897 . 10.2307/1382695. 1382695 . free .