Panama and Costa Rica. Range limits have not yet been determined.

Biogeographic Regions: neotropical (Native )

Head and Body length= 184-260mm Tail length= 223-290mm. As with other members of this genus, T. watsoni is large and has a long, thick, hairless tail with a white tip. They look like large species of the genus Rattus. The braincase is flattened and long. They have large, naked ears, a pointed snout, and long, black whiskers. The feet are broad and short with white toes and dark brown fur on top. Their body fur is long, soft, dense, and usually grayish brown above and pure white below. There is a great deal of color variation within populations. Older adults are usually paler in color.

• Terrestrial

Dense forest, mainly broadleaf rainforests, at low elevations and near bodies of water or rocky ledges. This species is arboreal.

Terrestrial Biomes: rainforest

Plant material including fruits, leaves, seeds, lichens, and bark.

Nothing is known about the reproduction of this species. Other species in this genus have a gestation period of 40 days and an average litter size of 2.3 young.

Very little is known about the populations of Tylomys watsoni, but they are considered uncommon. They could also be threatened by habitat destruction.

IUCN Red List of Threatened Species: least concern

Could be vectors for disease and pests in fruit plantations.