BRIEF DESCRIPTION: Fruiting bodies of Amanita manginiana sensu W. F. Chiu are medium-sized to large, sometimes very large. The cap is 50 - 150 (-200) mm wide, convex to applanate, grey to dark grey to brownish, darker in the center, innately fibrillose, and usually glabrous, although occasionally covered with a few white, membranous volval remnants. The cap's margin is smooth and non-appendiculate, but often with some pieces of annulus remnants hanging. The cap context is white.  [Ed. note: the two images, above show the same mushroom in different lights.]

The gills are free to subfree and white; the short gills are attenuate.

The stem is 80 - 150 x 5 - 30 mm, subcylindric to attenuate upwards, with a surface that is white and covered with white fibrillose to farinose squamules; the stipe's context is white; the stem's basal bulb is 20 - 35 mm wide, ventricose to clavate, or (occasionally) subglobose. At the stipe's base, the volva is limbate, with a free, white to dirty white limb. The annulus is apical to subapical, white, and easily broken during expansion of cap.

The spores measure (5.5-) 6.0 - 8.0 (-9.0) x (4.5-) 5.0 - 7.0 (-7.5) µm and are subglobose to broadly ellipsoid and amyloid. Clamps are not present at the bases of basidia.