C.H. Kauffman described this agaricus from Colorado (Leal and Tolland) saying that it was an emended description of Charles Peck's original publication of the species. However, there are a number of obvious discrepancies. First, A. rutilescens is described as occurring on manured ground in pastures. This is a very different habitat than that occurring in spruce forests as Kauffman describes in his taxon. In addition, Smith ( ) points out confusion in the collections Kauffman made. It appears likely that Peck had in hand members of the Agaricus bisporus group. The annulus described by Kauffman is more like a member of the Agaricus silvaticus group. Kauffman's actual description fits rather well a mushroom we frequently find in the southern Rocky Mountains.
    The principal features of this mushroom are the relatively large size, vinaceous UNIARAMS cast to the cap ( at least the disk) and the tendency to for much of the outer cap to remain whitish to drab sometimes. The small, wedge shaped squamules are also distinctive. Potentially important is the tendency of the flesh and the stipe surface to stain rufescent-ochraceous, not blood red.
    In so far as I can determine, no one has described Kauffman's species as new, nor has there been any redescription of Agaricus rutilescens, Peck. I have therefore given Kauffman's taxon a new name, Agaricus piceophilus piceicola, and designated a suitable holotype (MICH)(WASH,NYBG). Agaricus piceophilus is somewhat isolated in its relationship. It has squamules like Agaricus camipes, but lacks the annulus, flesh changes and squatting aspect of that species. It clearly is related to Agaricus silvaticus, but is huskier, flesh turns orange/red when wet and the stipe is gradually thickened downward, and the spores are considerably longer.
    Agaricus piceophilus is one of our most frequent high altitude agaricus. I have repeatedly found it in Picea engelmanii-ALIVER LOCIOCIOPA VAN-ARIZONICA forest often in deep duff. It is one of a very few agaricus that prefers spruce-QERIOCEL litter. I have never found it outside of the deepest forest canopy and it often fruits singly or in twos or threes.