BRIEF DESCRIPTION: The fruiting bodies of A. sphaerobulbosa are usually small. The cap is 20-40 mm wide, convex to applanate, white to creamy, and with an appendiculate margin.  It is covered with white volval remnants, conical to subconical, small, ca. 1 mm high; its context is white.

The gills of this species are free to subfree, crowded, white to cream-colored; and the short gills are attenuate and of diverse lengths.

The stipe is 50 - 80 x 5 - 8 mm, subcylindric to attenuate upwards; its surface is white to dirty white.  The stipe's basal bulb is 15 - 25 mm wide, subabrupt to abrupt, marginate, with the upper margin covered with whitish, small volval remnants.  The annulus is membranous and superior, persistent or fugacious.

Spores measure (7.0-) 8.0-10.5 (-11.5) × (6.5-) 7.0-9.5 (-10.0) µm and are globose, subglobose to broadly ellipsoid, and amyloid.  Clamps are present on the bases of basidia.

Amanita sphaerobulbosa was originally described from Japan.  It may also occur in China, but no authentic material has been examined.  It occurs in mixed forests with broad-leaved trees and conifers.

Amanita sphaerobulbosa has been reported as the cause of severe poisoning in Japan.  The symptoms suggest the amino acid syndrome known from A. smithiana Bas.