It produces small- to medium-sized fruit bodies, with brown caps up to 9 centimetres (3+1⁄2 inches) in diameter covered with pyramidal warts.

[2] Austrian mycologist Egon Horak later transferred it to the genus Oudemansiella, but did not provide a reason for making the new combination.

[3] In 1986, Pegler and Young proposed a classification for Oudemansiella based largely on spore structure, but they excluded O. macrospora, considering it a species of Amanita.

[4] Geoff Ridley examined Stevenson's holotype material and reduced L. macrosporus to synonymy with A. australis in 1993, explaining: The size, shape and amyloid reaction of the spores, the dimensions of the basidia, the presence of clamp connections and lamella margin cells indicate that this is Amanita australis Stevenson and easily fits into the concept of this taxon.

... Macroscopically the specimen lacks the typical pronounced basal bulb to the stipe and volva remnants on the pileus; however, it is not an unknown condition in this taxon.

[9] The shape of the A. australis cap is initially convex, later flattening out or even developing a central depression, and reaching diameters of 2–9 centimetres (3⁄4–3+1⁄2 inches) wide.

The remnants of the volva form conical to pyramidal warts that are most densely aggregated in the center, but become sparse and low towards the margin.

These cells are umber in colour, and arranged in chains perpendicular to the cap surface, becoming smaller and paler at tip of the wart, subtended by moderately abundant hyphae that are 4–10 μm wide.

[1] A. australis also bears some resemblance to the eastern North American and east Asian species A. abrupta,[8] which also has an abruptly bulbous stem base.