421.

Yungas Rice Rat

Hylaeamys yunganus

French: Oryzomys des yungas / German: Yungas-Reisratte / Spanish: Rata arrocera de Yungas

Other common names: Amazonian Oryzomys, Amazonian Hylaeamys

Taxonomy. Oryzomys yunganus Thomas, 1902, “Charuplaya, 1350 m,” on Securé River, Cochabamba, Bolivia.

This species is monotypic.

Distribution. C & SE Colombia, S Venezuela, and the Guianas S through E Ecuador and E Peru to C Bolivia and Amazonian Brazil.

Descriptive notes. Head-body 115-149 mm, tail 107-128 mm, ear 18-21 mm, hindfoot 26-31 mm; weight 35-53 g. The Yungas Rice Rat is medium-sized, with uniform and short coat (9 mm) but with longer hairs on dorsum, which is dark fawn to brownish black. Venter is grayish white, with bases and tips of gray hairs opaque white; line that demarcates flanks and venter is marked. Tip of snout is whitish, and bases of vibrissae are brown. Eyes have dark rings around them. Anterior and posterior legs are whitish dorsally. Tail is uniform graybrown or whitish below proximal area. Muzzle is long and pronounced. Eyes are large, long, well-pointed ears, blackish to dark brown, and bare in appearance; when they are tilted forward, they hardly reach ears. Vibrissae are thin and short. Claws are covered by scattered hairs. Most conspicuous external character distinguishing the Yungas Rice Rat is reduction in size or absence of hypothenar pad on hindfoot; however, given substantial individual variation of size and presence, this feature is not absolutely diagnostic. Females have four pairs of mammae: axial pair, pectoral, abdominal, and inguinal pairs. The Yungas Rice Ratis characterized by chromosomal polymorphism within and between western (2n = 58-60, FN = 62-66) and eastern populations (2n = 52-59, FN = 64-67).

Habitat. Flooded and dry primary, secondary, forest edge, gallery forest, and abandoned crops in lowland Amazonian areas from sea level to elevations of ¢.2000 m. The Ynugas Rice Rat prefers areas near bodies of water. When sympatric with the Western Amazonian Rice Rat ( H. perenensis), the Yungas Rice Rat is more common on terra firma.

Food and Feeding. The Youngas Rice Rat eats mainly fruits and seeds.

Breeding. Reproduction of the Yungas Rice Rat occurs year-round. Females usually produce two offspring (range 1-4). Nest of leaves and thin branches are built in hollow logs and small cavities on the forest floor, under rocks or logs, at bases of large trees, or in areas covered with abundant vegetation.

Activity patterns. Yungas Rice Rats are nocturnal.

Movements, Home range and Social organization. Yungas Rice Rats move among and on top of fallen logs.

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

Bibliography. Brito et al. (2014), Musser, Carleton et al. (1998), Ochoa et al. (1988), Patton et al. (2000), Patton, Weksler & Percequillo (2016), Percequillo (2015e), Thomas (1902b), Voss et al. (2001), Weksler et al. (2006).