Russula dissimulans Shaffer (1962)                                  *Collections: California and Idaho

This mastodonic Russula shows the same color changes upon bruising "Red to Black", which are typical for Russula nigricans. Shaffer's justification for making a new species is that the spores of dissimulans are distinctly larger than those of Russula nigricans, something that I myself confirmed when comparing to material from Europe and the Eastern USA. Whether this has sufficient taxonomic strength for speciation in this case is something that needs be analyzed using more contemporary methods. Some authors consider them to be synonyms. It is a typical species for the coastal forests, but II have never seen it in Sierra Nevada. Still I saw large fruitings in Idaho, so the range probably covers the entire Western North America. 

Gills -- subdistant -- one can stash quarters between them. Also thick & brittle

Spores: 8-9x7-7.2, very fine ornamentation as is typical for the members of this group

Collections from Idaho