The black-tailed tree rat, also called black-tailed acacia rat or black-tailed thallomys, (Thallomys nigricauda), is a species of rodent in the family Muridae. It is found in Angola, Botswana, Namibia and South Africa, where its natural habitat is subtropical or tropical dry shrubland. It is both nocturnal and arboreal and makes bulky nests in the trees, often acacias, where it feeds on leaves and buds.