BRIEF DESCRIPTION: The cap of Amanita pachyvolvata is 50 - 80 (-110) mm wide, hemispheric or ovate, then plano-convex, shiny or subviscid, rather pruinose toward the margin, more mat toward the center, with a striate-sulcate margin (35^±% of the radius), becoming rimose. The cap is sordid ochraceous or fauve-gray to bister over disc and a paler brown-yellow toward margin. The volva is absent.

The gills are creamy white or white or yellowish white, rather broad, with a fimbriate edge or slightly fimbriate and serrate edge. I have no information on short gills in this species.

The stem is (120-) 150 - 200 x 20 - 30 mm or (120-) 150 - 180 (-200) x (10-) 15 - 30 mm, white, then more or less grayish or yellowish gray, variegated, narrowing upward, and exannulate. The flesh is stuffed at first, then quickly hollow. The very large volval sac is white, membranous, and persistent.

The spores measure (10.2-) 11.0 - 14.2 (-15.0) x (9.5-) 10.8 - 13.2 (-15.0) µm and are globose to subglobose to broadly ellipsoid and inamyloid. Clamps are present at bases of basidia.

This species was originally described from France (Dép. Haute-Loire) under Fir and Spruce.