Its distribution comprises the Pilliga forest region of New South Wales, Australia, specimens have also been trapped in the Warrumbungle National Park and Weetalibah Nature Reserve.

P. pilligaensis is a small brown mouse with grey-brown upper parts, the head and back greyer, grading through russet flanks to white underparts.

They distinguished it from the similar species P. novohollandiae, P. delicatulus and P. hermannsburgensis on the basis of characters such as skull size and shape and the ratio between tail and head/body length.

[9] Recent research indicates that preferred habitat for this species includes shrubby woodlands and heathlands, particularly where Broombush Melaleuca uncinata and Bloodwood Corymbia trachyphloia occurs.

[1] Threats to the population in the Pilliga include exploration and infrastructure construction relating to coal seam gas, as well as habitat loss through forestry, predation by the introduced cat and fox, and competition from the house mouse.