390.

Robert's Arboreal Rice Rat

Oecomys roberti

French: Oecomys de Robert / German: Robert-Baumreisratte / Spanish: Rata arrocerra arboricola de Robert

Other common names: Robert's Oecomys

Taxonomy. Rhipidomys roberti Thomas, 1904, “Santa Ana de Chapada, a village stinated at an altitude of about ¢. 800 m, on the Serra do Chapada, some thirty miles [= 48 km] N.E. Cuyaba,” Mato Grosso, Brazil.

Taxonomy of O. roberti is poorly explored; unpublished metric studies recovered several different groups that need additional research. Monotypic.

Distribution. SE Colombia, E & S Venezuela, Guyana, Suriname, N & WC Brazil, E Peru, and extreme N & E Bolivia.

Descriptive notes. Head-body 111-135 mm, tail 138-164 mm, ear 14-17 mm, hindfoot 26-28 mm; weight 46-66 g. Robert's Arboreal Rice Rat is moderately large, with tail ¢.123% of head-body length and relatively short furforits body size (5-7 mm over mid-rump). Dorsal pelage is soft but slightly harsh to touch. Upperparts are bright tawny to fulvous brown, grading to ocherous on flanks, although without obvious lateral line. Venter ranges from all white (hairs single colored) to grayish white (hairs with gray bases and white tips), with varying degrees of intermediacy depending upon extent of gray-based hairs, or sometimes tinted with buffy or ocherous wash on chest and belly; dorsal and ventral pelage contrasts sharply in individuals with mostly white underparts but only moderately in individuals with grayish white or grayish buff venters. Tail is wholly dark brown; caudal hairs are so short thattail appears naked macroscopically, revealing fine scale rows, and no tuft at tip is formed. Pinnae are relatively short and brown; tops of hindfeet are white or tinged ocherous. Chromosomal complement is 2n = 80, FN = 114.

Habitat. Varzea forest along Jurua River, more rarely edges of second growth forest, ecotones of dense growth around natural tree falls in primary forest, viney forest with low canopy, and semideciduous forest from sea level up to elevations of ¢.800 m.

Food and Feeding. No information.

Breeding. Litters of Robert’s Arboreal Rice Rats have 2-3 young.

Activity patterns. Robert’s Arboreal Rice Rats were captured equally on the ground and in the canopy.

Movements, Home range and Social organization. No information.

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

Bibliography. Carleton & Musser (2015), Carleton et al. (2009), Costa, Weksler & Bonvicino (2016), Emmons et al. (2006), Hershkovitz (1960), Linares (1998), Patton et al. (2000).