BRIEF DESCRIPTION: The following is largely based on the original description (Wood 1997).

The cap of Amanita allostraminea is up to 120 mm wide, white to ivory, convex to plane, smooth, dry, with a nonstriate and not clearly appendiculate margin.  The cap is decorated with small, flat, low, membranous scales on the outer part, concolorous with the cap.

The gills are free, thick, subdistant, deep cream, with a concolorous margin.  Short gills are present in at least one series.

The stem is up to 140 × 20 mm, equal, smooth, and white to off-white. The ring is prominent, persistent, membranous, skirt-like, cream, and not striate on the upper surface.  The base is bulbous to slightly top-shaped, white with scattered concentric rings of volval remains.  Wood states it also bears "scattered buff marks."

The spores measure 9.9 - 11.4 (-13.5) × 8.4 - 10.5 (-11.1) µm and are subglobose to broadly ellipsoid and amyloid.  Clamps are present but sparse to rare at bases of basidia.

Wood describes this species from New South Wales, Australia as occurring in association with Allocasuarina.  So far as we know, this species is known only from the type specimen.