The specimens were collected by J. T. Tunney and forwarded to the British Museum, Thomas recognising the field worker in the specific epithet.

The type used in the description was a female collected at Mary River, in the Northern Territory of Australia, and two other unlabelled specimens.

[3][2] The upper side of the pelage is a toffee-like shade of brown, said to be appealing in appearance, which grades into the lighter cream or greyish white at the underside.

Rattus tunneyi has pale pinkish ears that are 15 to 20 mm long and large eyes that have a bulging appearance.

[6] The distribution range of the east coast subspecies R. tunneyi culmorum is from Coffs Harbour in New South Wales to Coen in Queensland.

The fields of sugar cane found at the eastern coast may host the species, and they are observed at camp-sites or rocky slopes in the Kakadu National Park.

[3] The preference of habitat includes woodlands, dense sedges or grassy under-storey within monsoon forest, and wetter open grasslands.

[9] Pale field rats are vegetarians that eat grass stems, seeds, tubers and roots, and rest in shallow burrows dug in loose, crumbly soil during the day.

[3] Rattus tunneyi was identified as a damaging pest species in Queensland, where they feed at the roots of hoop pine, Araucaria cunninghamii, and destroy partially matured trees in plantation crops.