Octodontomys gliroides (Gervais & d'Orbigny, 1844)

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 : 539-540

6.

Mountain Degu

Octodontomys gliroides

French: Octodon a longue queue / German: Pinselschwanzratte / Spanish: Degu del Monte

Other common names: Chozchori, Long-tailed Octodon

Taxonomy. Octodon gliroides P. Gervais & d’Orbigny, 1844 ,

“des Andes boliviennes, a Lapaz,” La Paz, Bolivia .

Phylogenetic position of Octodontomys remains uncertain. Most molecular studies support a sister relationship with the Chilean clade ( Octodon [ Aconaemys + Spalacopus ]), while others place it basal to the desert-adapted Argentinean clade ( Octomys [ Tympanoctomys + Pipanacoctomys ]). Monotypic.

Distribution. Andean and sub-Andean zones of SW Bolivia, N Chile, and NW Argentina.

Descriptive notes. Head-body 161-182 mm, tail 100-190 mm; weight 100-200 g. The Mountain Degu is mediumsized to large-sized. Skull is nearly similar to that of species of Octomys . Rostrum is relatively long and narrow. Tympanic bullae are large and well developed, like other desert-adapted octodontids. Pelage is long and silky. Dorsal fur is grayish brown, and venteris white, with gray bases to hairs. Chin and throat are pure white.

Ears are large and covered with short grayish hairs. Tail is long (c.80% of head-body length) and bicolored, with well-developed, brown-ocher brush extending from tip. Chromosome complement is 2n = 38, FN = 64.

Habitat. Open, xeric, and rocky areas of the Puna , dominated by columniform cacti ( Browningia , Cereus, Trichocereus , and Opuntia , Cactaceae ), shrubs, and herbaceous plants, at elevations of 2000-5000 m. The Mountain Degu is a scansorial species, but it can make superficial burrows in patches of columnar and ground-level cacti or shrubs, where they feed on vegetation, hide from predators, and rear offspring. Tail is used for substrate support when climbing.

Food and Feeding. The Mountain Degu is herbivorous and eats on cacti and pods and seeds of acacia ( Acacia , Fabaceae ). Individuals feed on acacia sheaths in winter and cactus fruits in summer; they also eat leaves and bark of resinous shrubs and can use cactus tissues to satisfy water requirements.

Breeding. Gestation of the Mountain Degu is 100-109 days, with litter sizes of 1-3 offspring. Precocial young are born completely furred and with open eyes. Juveniles in various stages of development have been found in November, and pregnant females and young in January and May.

Activity patterns. The Mountain Degu is nocturnal. Its activity is highest after sunset and decreases after sunrise.

Movements, Home range and Social organization. The Mountain Degu is social and communicates with gurgles, twitters, and squeaks in low, mid-, and high frequencies. A recent study of two populations of Mountain Degus identified social groups of 2-3 or 2—4 individuals. Mountain Degus from the same social group always used one burrow system for resting and hiding. Males have larger home ranges than females.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Mountain Degu has no apparent conservation threats, and it can live in areas of high human densities. It has a wide distribution and presumably a large overall population.

Bibliography. Contreras, Torres-Mura, Spotorno & Walker (1994), Contreras, Torres-Mura & Yanez (1987), Diaz, G.B. & Ojeda (2000), Diaz, M.M. (1999), Gallardo (1992), Gallardo & Kirsch (2001), George & Weir (1972b), Honeycutt et al. (2003), Iriarte (2008), Mann (1978), Munoz-Pedreros (2000), Opazo (2005), Pine et al. (1979), Reig (1986), Rivera (2013), Rivera et al. (2014), Rowe etal. (2010), Tirira, Boada, Weksler et al. (2008a), Upham & Patterson (2012), Weir (1974).

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. Andean and sub-Andean zones of SW Bolivia, N Chile, and NW Argentina.