The gray-bellied mountain rat is one of only two species in the genus Limnomys. The other, and the rat's only close relation, is the Mindanao mountain rat, Limnomys sibuanus. While gray-bellies have been recorded only in the Kitanglad Mountains, the Mindanao is considered to be endemic to the mountains of the island of Mindanao and has been recorded from Mount Apo and Mount Malindang as well as from Mount Kitanglad. It has also been observed at lower elevations, its range being between about 2,000 metres and about 2,800 metres.