The Colombian forest mouse (Chilomys instans) is a species of rodent in the family Cricetidae. Some authorities consider it to be the only species in the genus Chilomys, while others accept Chilomys fumeus as being a valid species, and it may form part of a species complex. It is found in Colombia, Ecuador, and Venezuela.
Description
Chilomys instans is very similar to Chilomys fumeus in size and appearance. Both are small sigmodontines, with a head-and-body length of 72 to 102 mm (2.8 to 4.0 in) and a tail length of 102 to 137 mm (4.0 to 5.4 in). The ears are medium-sized and clad in short hairs, and the body fur is woolly and short. The dorsal surface is dark grey to greyish-brown and the underparts are a similar colour. The hind feet are narrow, and the slender tail is clad with short hairs, and often has a white tip. There are three pairs of mammary glands. The chief differences between the two species lies in the morphology of the skull.
Taxonomy
Based on both molecular and morphological studies, C. instans is believed to be most closely related to thomasomyine sigmodontines such as Aepeomys, Rhagomys, Rhipidomys and Thomasomys. The genus' morphology has been described as "peculiar".
