649.

Reddish-backed Oldfield Mouse

Thomasomys pyrrhonotus

French: Thomasomys a dos roux / German: Rotrlicken-Paramomaus / Spanish: Raton de erial de dorso rojizo

Other common names: Reddish-backed Thomasomys, Thomas's Oldfield Mouse

Taxonomy. Hesperomys pyrrhonotus Thomas, 1886, Tambillo, Rio Malleta, Cajamarca, Peru.

This species is monotypic.

Distribution. Andes in NW Peru (Piura and Cajamarca regions).

Descriptive notes. Head-body 137-144 mm, tail 190 mm, ear 19-5-22 mm, hindfoot 30-31 mm. No specific data are available for body weight. Dorsum of the Reddish-backed Oldfield Mouse is rufous, with head lighter and undersurface whitish with small orangish pectoral streak. Pelage above metatarsals is pale orange, and digits are brown. Ears have whitish post-auricular patch. Mystacial vibrissae are blackish, moderately long, and extended slightly or distinctly beyond posterior margin of pinnae when bent. Tail is unicolored and relatively long (c.120% of head-body length), and basal c.1cm part is cover with red-tipped body hair. Hindfoot is moderately long with long hallux, extending to interphalangealjoint of second digit; fifth digit is moderately long or long, extending to base of claw of fourth digit or close.

Habitat. Montane forest and shrubby paramo at elevations of 1200-3100 m. The Reddish-backed Oldfield Mouse has also been collected in tall shrub habitat (Cachil, Cajamarca), secondary montane forests and bamboo montane forests (Monteseco, Cajamarca), and cloud forest (Cutervo, Cajamarca).

Food and Feeding. No information.

Breeding. Breeding season of teh Reddish-backed Oldfield Mouse occurs in wet season; females have 2-3 young.

Activity patterns. The Reddish-backed Oldfield Mouse is nocturnal.

Movements, Home range and Social organization. The Reddish-backed Oldfield Mouse probably lives in trees. Based on limited observations, one individual was an excellent climber, making good use of digits ofits hindfoot to grasp branches and its long tail for balance.

Status and Conservation. Classified as Vulnerable on The IUCN Red List. Populations of the Reddish-backed Oldfield Mouse have probably declined because of habitat fragmentation and destruction and degradation of habitat. This species occurs in a narrow elevational range that limits its ability to disperse.

Bibliography. Musser & Carleton (2005), Pacheco (2015b), Pacheco et al. (2009), Pacheco, Tirira & Boada (2008b), Thomas (1882, 1886b).