Microryzomys altissimus, Osgood, 1933

Don E. Wilson, Russell A. Mittermeier & Thomas E. Lacher, Jr, 2017, Cricetidae, Handbook of the Mammals of the World – Volume 7 Rodents II, Barcelona: Lynx Edicions, pp. 204-535 : 442

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).

Figures

458. Forest Small Rice Rat (Macroryzomys minutus), 459. Highland Small Rice Rat (Microryzomys altissimus), 460. Peruvian Rice Rat (Oreoryzomys balneator), 461. White-throated Montane Forest Rat (Drymoreomys albimaculatus), 462. Gray Rice Rat (Eremoryzomys polius), 463. Medium-tailed Rice Rat (Eremoryzomys mesocaudis), 464. Lund’s Water Rat (Lundomys molitor), 465. Paraguayan Rice Rat (Sooretamys angowya), 466. Brazilian False Rice Rat (Pseudoryzomys simplex), 467. Venezuelan Marsh Rat (Holochilus venexuelae), 468. Amazonian Marsh Rat (Holochilus sciureus), 469. Chacoan Marsh Rat (Holochilus chacarius), 470. Brazilian Marsh Rat (Holochilus brasiliensis), 471. Crafty Marsh Rat (Holochilus vulpinus), 472. Lagiglia’s Marsh Rat (Holochilus lagigliai), 473. Langguth’s Rice Rat (Cerradomys langguthi), 474. Vivo’s Rice Rat (Cerradomys vivoi), 475. Maracaju Rice Rat (Cerradomys maracajuensis), 476. Lindbergh's Rice Rat (Cerradomys scotti), 477. Akroa Rice Rat (Cerradomys akroai), 478. Marinho’s Rice Rat (Cerradomys marinhus), 479. Terraced Rice Rat (Cerradomys subflavus), 480. Goytaca Rice Rat (Cerradomys goytaca), 481. Ucayali Water Rat (Amphinectomys savamis), 482. Trinidad Water Rat (Nectomys palmipes), 483. Magdalena Water Rat (Nectomys magdalenae), 484. Western Amazonian Water Rat (Nectomys apicalis), 485. South American Water Rat (Nectomys rattus), 486. Atlantic Water Rat (Nectomys squamipes)

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