BRIEF DESCRIPTION: The following description is based on the original description by Beeli (1936).

The cap of A. loosii is 130 - 160 mm wide, globose then plano-convex, smooth, brilliant white becoming cream with a tan (chamois) center, with a striate margin.  Volval remnants are absent.  The flesh is white.

The gills are free, crowded, narrowed to a point at the stem, up to 10 mm broad, white, with minutely irregular edge.

The stem is 100 - 120 × 18 - 25 mm, cylindric or narrowing upward slightly, smooth, becoming hollow, pure white, smooth.  The ring membranous, skirt-like, pure white, and attached near the top of the stem.  The volva is ample, membranous, and brown on the exterior.  The flesh is white.

The mushroom is edible and very much appreciated by the local population.  The flesh has an odor of citron. The taste is agreeable but not very pronounced.

The spores measure 14 - 15 × 10 - 11 µm and are probably broadly ellipsoid to ellipsoid and inamyloid.  Clamps are probably present at bases of basidia. Walleyn and Verbeken (inlit.) selected a lectotype for A. loosi and measured spores from the lectotype with the following results: 10.1 - 12.5 x 7.4 - 10.7 µm; however, they noted that the basidiomes had become quite moldy.  RET's experience indicates that moldy specimens tend to have smaller spores than those in good condition and that spores and the apices of basidia are often destroyed by invasive molds.

This species was originally described from the then Belgian Congo.