502.

Black-and-Yellow Rice Rat

Melanomys chrysomelas

French: Mélanomys noir et jaune / German: Schwarzgelbe Dunkelreisratte / Spanish: Rata arrocera negra y dorada

Taxonomy. Oryzomys chrysomelas J. A. Allen, 1897, Suerre, Limon, Costa Rica.

M. chrysomelas is traditionally subsumed under M. caliginosus; here it is resurrected following molecular results of|. D. Hanson and R. D. Bradley in 2008. A complete revision of the genus is pending. Monotypic.

Distribution. SW Honduras, Nicaragua, and Costa Rica; occurrence in Panama uncertain.

Descriptive notes. Head-body 110-130 mm, tail 80-100 mm, hindfoot 24— 28 mm. No specific data are available for body weight. Melanomys includes mediumsized vole-like oryzomyines, with tails shorter than head-body length. Dorsum is dark brown; venteris grayish or yellowish brown. Ears are small and slightly hairy. Mystacial vibrissae are short and sparse. Manus and pes are covered dorsally with short and dark hair, and manual claws are long and keeled. Tail is unicolored and dark, sparsely haired, without apical tuft. There are four pairs of mammae. Upperparts of the Black-and-Yellow Rice Rat are very dark brown; hairs are conspicuously tipped with yellowish rufous; sides are brighter and more rufous than back; underparts have yellowish brown tips on long hairs, concealing plumbeous basal part of pelage; ears are black; feet and tail are dark brownish black, and tail is not appreciably lighter below. Chromosomal complement is 2n = 56, FN = 58.

Habitat. Evergreen humid forests from near sea level to elevations of ¢.1000 m (more commonly below 500 m). The Black-and-Yellow Rice Rat also occurs in abandoned plantations, and individuals have been trapped around leaves and other debris associated with logs and buttress of large trees.

Food and Feeding. Stomach contents of Black-and-Yellow Rice Rats contained plant material; captive individuals preyed on insects.

Breeding. Pregnant or lactating Black-and-Yellow Rice Rats were recorded in February—March and August; eleven pregnant females has an average of 3-5 embryos (range 1-6); and one female had postpartum estrus.

Activity patterns. The Black-and-Yellow Rice Rat is terrestrial and apparently nocturnal and diurnal.

Movements, Home range and Social organization. No information.

Status and Conservation. Not assessed on The IUCN Red List as a separate species from the Dusky Rice Rat ( M. caliginosus), which is classified as Least Concern.

Bibliography. Allen (1897a, 1908, 1913b), Gardner (1983), Goldman (1918a), Goodwin (1946), Hanson & Bradley (2008), McPherson (1985), Rodriguez & Chinchilla (1996), Villalobos-Chaves et al. (2016).