BRIEF DESCRIPTION: The cap of A. solitaria is (50-) 70 - 160 (-200) mm wide, globose at first, convex with expanding, soon plano-convex to flat with a slightly depressed center, dry to subviscid, with a nonsulcate, projecting, slightly appendiculate margin.  The cap is dingy white to dingy cream to pale silvery gray to pale brownish gray especially near the center, with age sometimes becoming pale brownish straw yellow.  The surface texture at the center can be subfelted and minutely fibrillose at the margin, later becoming smooth.  The cap is usually decorated with small, whitish to concolorous to slightly darker gray, acute-conical to low conical, subfibrillose, adnate to subdetersile warts sometimes having what appears to be bits of spiderweb at the base.

The gills are rather crowded, narrowly adnate to just free, broad, ventricose, and greenish cream-yellow.  The short gills are subtruncate to more or less attenuate.

>The stem is (60-) 100 - 140 (-200) x (10-) 15 - 25 (-30) mm, rarely subcylindrical, pointed to rounded, solid, whitish to pale straw yellow, and annulate.  The membranous, persistent annulus can be double as in A. cokeri (E.-J. Gilbert & Kühner) E.-J. Gilbert.

>The spores measure 9.0 - 12.0 (-14.5) x 6.0 - 8.0 (-11.5) µm and are amyloid and broadly ellipsoid to elongate.  Clamps are present at bases of basidia.

This species is to be found in Europe, Western Asia, and Mediterranean Africa.  According to Borovička (2006), the species often occurs co-located with A. strobiliformis (Paul. ex. Vitt.) Bertillon in association with Tilia in the Czech Republic.

For a set of closely related taxa for comparison (species of Bas' stirps Solitaria), see A. cokeri.  The most recent in-depth revision of A. solitaria is by Neville and Poumarat (1996).