Monoon australe is a plant in the custard apple family Annonaceae found in the northern parts of the Australian states of Western Australia, the Northern Territory and Queensland. It was originally described as Popowia australis by the English botanist George Bentham in 1863, but it was transferred to its current combination in 2012 in a review of the closely related genus Polyalthia conducted by the botanist Bine Xue and others.
, this species has been assessed to be of least concern by the International Union for Conservation of Nature (IUCN) and by the Queensland Government under its Nature Conservation Act.