BRIEF DESCRIPTION: The following description is based on Ridley (1991).

The cap of Amanita nothofagi is 30 - 130 mm wide, convex to plano-convex, eventually depressed in the center, viscid when young or wet, with a very short striate, nonappendiculate margin. The color varies from buff to pale buff to gray to dark grayish sepia streaked with fuscous, hazel or cinnamon to buff.  The irregular shaped volval remnants form small to extensive felted patches, dull grayish sepia to sepia; the remnants are occasionally scab-like and rarely arranged concentrically.  The flesh is white or stained mouse-gray under the center of the cap's skin.

Gills are crowded, free, 6 - 10 mm wide, white to cream; the short gills are subtruncate.

Its stem is 40 - 140 × 5 - 25 mm, narrowing upward, flaring slightly at the top, hollow, smooth or occasionally breaking into bands or fibrillose scales below the ring, white, sparsely floccose, occasionally breaking into transverse bands above the ring, white to grayish sepia streaked with a band or rim of buff to grayish sepia volval remnants.  The basal bulb is small or occasionally abrupt, 10 - 30 mm wide.  The ring is membranous, striate, white, sordid white, buff, grayish sepia or lavender-gray, skirt-like, sometimes tearing and adhering to the cap edge.  The flesh is white to pale buff.

The spores measure (6.5-) 7.5 - 9 (-13) × (6.5-) 7.5 - 9 (-13) µm and are globose to subglobose, infrequently broadly ellipsoid, rarely ellipsoid and amyloid. Clamps are absent at bases of basidia.

Originally described from the North and South Islands of New Zealand associated with Nothofagus, Leptospermum, and Kunzea.

Ridley states that this is most common species of Amanita in New Zealand and also the most variable in "size, stature, coloration, and volva configuration."  Pale individuals have been incorrectly determined as A. excelsa (Fr. : Fr.) Bertillon in Dechambre, which does not occur in New Zealand.  Ridley suggests that A. luteofusca Cleland & E.-J. Gilbert of Australia has a number of similarities suggesting a relation to the present species.  Caps without bright colors, rings and volvas that are gray or brown and sometimes have violet tints are characters common to a number of Amanita taxa now known from New Zealand, Australia, and Chile -- suggesting that they shared similarly dull colored Gondwanan ancestors.
-- R. E. Tulloss