622.

Unicolored Oldfield Mouse

Thomasomys monochromos

French: Thomasomys monochrome / German: Einfarbige Paramomaus / Spanish: Raton de erial unicolor

Other common names: Unicolored Thomasomys

Taxonomy. Oryzomys (Erioryzomys) monochromos Bangs, 1900, Paramo de Macotama, Sierra Nevada de Santa Marta, Magdalena, Colombia.

This species is monotypic.

Distribution. Extreme N Colombia (Magdalena Department).

Descriptive notes. Head-body 105-120 mm, tail 124 mm, ear 18-20 mm, hindfoot 24-27 mm; weight 36 g. Dorsum ofthe Unicolored Oldfield Mouse is rich brown, more yellowish or raw umber on sides, and underparts are dull yellowish wood brown; venter not countershaded relative to dorsal pelage. Mystacial vibrissae are moderately long, extending only slightly beyond posterior margin of pinnae when bent. Hindfoot is white above but irregularly marked with dusky. Tail is short to medium for genus (96— 124% of head-body length), uniformly dusky brown, and finely haired. Ears are nearly naked, and dusky in color. Chromosomal complement is 2n = 42 and FN = 42.

Habitat. Montane forest and paramo at elevations of 2000-3600 m. Unicolored Oldfield Mice were recorded in tropical cloud forest remnants where most of the surrounding land was converted to pastures or forested with exotic trees.

Food and Feeding. No information.

Breeding. No information.

Activity patterns. No information.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Endangered on The IUCN Red List. The Unicolored Oldfield Mouse has a possible extent of occurrence of 3600 km?, but it is known from only a single location. Extent and quality of habitat continues to decline in this area.

Bibliography. Bangs (1900), Eisenberg & Redford (1999), Gémez-Laverde & Pacheco (2008c), Pacheco (2003, 2015b).