Comment: why var. guessowii? I have definitely seen that variety:

http://mushroomobserver.org/77203?q=DTbe

This is much less robust, has a thin, flat cap, minimal volval remnants hanging from the margin, and a characteristic stipe base. The photo is typical of several of specimens from the same site in 2010 (which could be posted). 2011 did not produce much of anything. I have not done microscopy, but I was hoping that this observation (and site) was a good example of the ‘type’ A. muscaria…, I know there are issues; certainly this could be A. muscaria var. guessowii.