459.

Highland Small Rice Rat

Microryzomys altissimus

French: Oryzomys des sommets / German: Hochland-Kleinstreisratte / Spanish: Rata arrocera pequena de tierras altas

Other common names: Paramo Colilargo

Taxonomy. Oryzomys (Microryzomys) minutus altissimus Osgood, 1933, La Quinua, mountains north of Cerro de Pasco, Pasco, Peru.

This species is monotypic.

Distribution. C Andes in Colombia and W & E Andes in Ecuador and N Peru.

Descriptive notes. Head-body 62-99 mm, tail 104-131 mm, ear 12-16 mm, hindfoot 17-25 mm; weight 10-24 g. Dorsal hair of the Highland Small Rice Rat is soft and woolly, tricolored with grayish bases, yellowish in the middle, and blackish tips. Ventral hair is bicolored, with dark gray bases and yellowish graytips. Vibrissae are abundant and long, extending beyond ears when bent. Hindfeet are whitish, with claws covered almost completely by long hairs. Fifth digit extends beyond junction of first phalanx of fourth digit. Tail is thin and ¢.137% of headbody length, bicolored, with short and scattered hairs. Skull is slightly heavier with broader braincase than that of the Forest Small Rice Rat (M. minutus), incisive foramina is longer, and incisor tubercle of mandible is small and indistinct. Females have four pairs of mammae. Chromosomal complement is 2n = 57, FN = 58, based on a single female from Ancash, Peru, judged to be heterozygote for a Robertsonian translocation.

Habitat. Subalpine and paramo formations and montane rainforest at elevations of 2500-4300 m.

Food and Feeding. The Highland Small Rice Rat eats arthropods, larvae, parts of plants, and seeds.

Breeding. No information.

Activity patterns. The Highland Small Rice Rat is terrestrial.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Barnett (1999), Carleton (2015a), Carleton & Musser (1989), Eisenberg & Redford (1999), Gardner & Patton (1976), Gébmez-Laverde, Rivas & Delgado (2016), Lee et al. (2015), Musser & Carleton (2005), Noblecilla & Pacheco (2012), Pacheco et al. (2009), Sahley et al. (2015), Tirira (2007), Voss (2003).