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

The cap of Amanita fuscobrunnea is up to 35 mm wide, convex, smooth, dry, gray, with a nonstriate margin.  The volva is present as prominent, dark brown pyramidal warts, smaller towards the margin, and may be reduced at the margin to flat scales.

The gills are free, thin, crowded, white, and marginate with a thin pale brown edge.  The short gills are present in at least one series.

The stem is up to 50 × 6 mm, narrowing upward, white, covered with dark brown, powdery granules all over, and marked with distinct concentric dark zones on its lower part and on the top of the bulb.  The ring is membranous, broadly flaring, dull gray-brown, with a dark brown margin.  The bulb is small and ellipsoid.

The spores measure (5.7-) 6.6 - 7.5 × 5.4 - 6.6 µm and are subglobose to broadly ellipsoid and amyloid.  Clamps are absent at bases of basidia.

Wood describes the mushroom as occurring in sclerophyll forests from the state of New South Wales, Australia.  A sclerophyll forest in the Australian bush is a forest of hard-leaved plants including Eucalyptus in the overstory (wikipedia).  This species is known only from the type collection.