See: http://mushroomobserver.org/69780?q=6wNR

Created: 2011-09-12 22:13:39 ADT (-0300)
By: Noah Siegel (Amanita virosa)
Summary: nobilissimus vs. edulis

The cap surface texture is key. “tomentose to fasciculate-tomentose, becoming appressed-tomentose, strongly pitted to corrugated…” People on MO seem to be assigning various and sundry porcini to nobilissimus based on the reticulation, but stalk reticulation is not a very good character in the edulis group while the nature or structure of the cap cuticle is.
B. reticulatus in Europe, for example, is often very prominently reticulate but not always. The original description of B. nobilissimus is apparently based on a single locality so there hasn’t been much of a chance to observe the consistency of reticulation within the species. Specimens I have seen showed coarse, lengthy reticulation in youth but scarcely any in old age, while the cap surface showed the fascicled hairs in all stages. I hope that is helpful.

Here is a closeup photo of the cap of B. nobilissimus