The spore data suggests the possibility that the species represented here is Amanita malleata.
There are many names that have been generated for taxa with average spores broadly ellipsoid to ellipsoid (with overall average Q < 1.30 for all spores measured in a “good-sized” sample), a cap including a grayish tint, a volval sac that is somewhat weaker than that of other species in section Vaginatae (but doesn’t turn gray as in A. submembranacea). And I’m rather certain that there are fewer species than there are names.
Without zaca’s microscopic data, no progress could have been made by an American who knows the group from dried material (e.g., type studies).
With zaca’s data, one can at least point to a sample taxon that would fit the data fairly well. I generated a comparison sporograph on
http://www.amanitaceae.org/?User_sporograph
There was a fairly good match between zaca’s data and the data made up from type studies of malleata and two of its synonyms that have valid names.
If interested in further details, one can see
http://www.amanitaceae.org/?Amanita_malleata
Very best,
Rod
