The Transitional Colilargo is a small rodent from the Cerrado around Brasília, Brazil. It has a dark stripe along its back and has been found mainly in wet grassland in recent surveys.
Its back is dark brown with a darker stripe down the middle, while the underside is cream-gray. It has a long tail and long hind feet.
Four individuals were caught in grasslands near Brasília in January–February 2002. Three were in wet grassland and one in dry grassland.
The five examined specimens had head-and-body lengths of 56–73 mm. The four collected in 2002 weighed 6–9 g and included juveniles.
The ears are short and rounded, covered with dark brown fur. The soles of the hind feet are hairless, with well-developed scales.
The tail has conspicuous overlapping scales and a small tuft of hair at its tip.
An extinction-risk assessment has not been added yet.