The spores are proportionately narrower than those of A. jacksonii. Considering the color distribution on the cap and the spores, I’m inclinded to say that this is not A. jacksonii. I’m going to spend a little more time looking at spores from the gills near the cap edge because these mature last, and I am hoping that I might find some “closer to typical” spores in this region.
Unfortunately, the range of spore size is very small and the hoped-for “bell curve” shape of the distribution of spore length is truncated…indicating that there would have been larger values of length, but that something (probably age of the basidiome prior to drying) affected the spore size, which is abnormal. This creates a problem for determination because the “original” collection of sp-S10 was apparently immature and bears “giant” spores. Hence, if the two collections belong to a single species, neither are typical in terms of spore size and shape distribution. Headache. Patrick, I hope you find another collection. If you can get a spore print and then dry the specimen as quickly as possible, it’s possible for us to make some progress on understanding sp-S10.