Comment: then no further discussion or at least firmer determination is possible.

nothing that you have put forth…white color, robust fruit body, scurfy stipe, length and depth of striations, thickish veil, inner limb to volva, hollow stipe, would rule out velosa. they are all variable characters, and all found in velosa, although sometimes uncommonly.

even the spores are a match, and that is the opinion of one who measures thousands of the damned things! (that would NOT be me.)

to prove your point, that this is something different, you need to come up with better, more compelling evidence. and to do that, you gotta save the mushroom.