I cannot add anything further beyond the level of detail that the pictures provide. In the absence of any definitive information on the stem base, the next most useful feature of this Amanita is the spectacular and well preserved skirt-like ring with a heavy appendiculated margin. The striate cap margin is also visible, as the crowded gill arrangement with frequent short gills and prominent warts on the pileus. I don't know much about Amanitas, so my confidence in the name I give it is fairly low...