5, see text Leptomys is a genus of rodent endemic to New Guinea.

It is considered part of the New Guinea Old Endemics, meaning it was part of the first wave of murine rodents to colonize the island.

Leptomys are seen to have minimal adaptations to their aquatic life style.

The third molar which is lost is many rodents is retained, albeit smaller.

Small eyes and ears can be seen amongst its velvety soft fur.