Amanita aporema

The following description is based on the original description by Boedijn (1951).

The cap of A. aporema is 80 - 140 mm wide, plano-convex, red-brown, paler towards the margin, smooth, with a sulcate-striate margin (striations extend nearly half the radius of the cap). The flesh is white, 5- 8 mm thick over the stem, rapidly thinning towards the margin.

The gills are free, dirty white, and 7 - 11 mm broad in the middle.

The stem is 120 - 200 × 12 - 20 mm, narrowing upward, hollow, dirty white, and smooth. The central cylinder of the stem is 8 - 14 mm wide. The saccate volva is large, 40 - 60 x× 25 - 35 mm.

The spores measure 9 -12.5 µm in diameter and are globose. Zhu L. Yang's examination of the type (Yang et al. 2004) yields the following measurements: (9.0-) 9.5 - 11.0 (-12.5) × (8.0-) 8.5 - 10.5 (-12.0) µm and are globose to subglobose and inamyloid. Clamps are present at bases of basidia.

This species was originally described from Sumatra.  Its natural habitat is unknown.

Yang observed (Yang et al. 2004) that due to the plentiful clamps in the fruiting body, Amanita aporema is more closely related to A. princeps Corner & Bas than to similar exannulate species in section Vaginatae.

Because the holotype is preserved in alcohol and because tissue so preserved tends to shrink, the spore measurements provided by Yang may be smaller than those that are found in fresh material, dried material, or material preserved in a formaldehyde-alcohol solution.

Given the above and the fact that macroscopic colors, dimensions, and spore measurements and shape are so similar in the two species, also given that Boedijn never saw A. aporema fresh and based his description on a twenty-six year-old specimen preserved in alcohol that Yang reports to be presently in poor condition, it is possible that A. princeps is a synonym of A. aporema.  However, this may be unprovable given the existing material.—R. E. Tulloss and L. Possiel