323.

Peruvian Cotton Rat

Sigmodon peruanus

French: Sigmodon du Pérou / German: Peru-Baumwollratte / Spanish: Rata de algodén de Peru

Taxonomy. Sigmodon peruanus J. A. Allen, 1897, Trujillo, Libertad, Peru.

This species is monotypic.

Distribution. Pacific coastal plain and adjacent Andean foothills of W Ecuador and NW Peru.

Descriptive notes. Head-body 120-172 mm, tail 79-116 mm, ear 16-20 mm, hindfoot 28-34 mm; weight 72 g. The Peruvian Cotton Rat is relatively large-bodied, with proportionately short tail and hindfeet. Dorsal pelage is short (14 mm long); back is pale ashy gray to dark brown, grizzled with black and yellow; sides of head and forelimbs are pale buffy; hindlimbs are pale buffy gray; ears are colored as the surrounding body; lower parts are pale yellowish gray, but hairs are gray at their bases; and tail is unicolored, pale yellowish graybrown, quite hairy with hairs concealing annual scales. Cranially, the Peruvian Cotton Rat can be distinguished from all other congeners by its complete, primitive stapedial circulation. It can be distinguished from other South American Sigmodon by long nasal bones; unconstricted interorbital region; short incisive foramina (rarely extending to molar alveoli); very narrow, short, and grooved palatal bridge with deep postero-lateral sulci; posterior palatal foramina always bordered by maxillary and palatal bones; large auditory bullae; broad, strongly opisthodont, ungrooved upper incisors; upper molars with alternate, acutely angled cusps; and first mandibular molars usually with only three well-developed roots. Chromosomal complement is 2n = 52, FNa = 50.

Habitat. Xeric, semiarid, and often deforested landscapes, including riverine habitats in primary and secondary dry forests, wet natural grasslands, and agricultural fields from sea level to elevations of ¢.1600 m. Nests are usually constructed under logs and rocks or in dense clumps of grass.

Food and Feeding. The Peruvian Cotton Rat eats green plant material, fungi, and some seeds; insects are eaten, probably opportunistically.

Breeding. No information.

Activity patterns. The Peruvian Cotton Rat is terrestrial and is active during the day and night.

Movements, Home range and Social organization. The Peruvian Cotton Rat constructs runways through grass or other low herbaceous vegetation.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Although the Peruvian Cotton Rat is considered uncommon, populations are considered stable, with no major threats, and it occurs in several protected areas in Ecuador and Peru. Introduced murid rats pose a potential problem that requires further attention.

Bibliography. Allen (1897c, 1901a, 1903a, 1913a), Brito, Orellana-Vasquez et al. (2015), Swier et al. (2009), Thomas (1921e), Tirira (2007), Voss (1992, 20151), Zeballos, Vivar & Tirira (2016).