The Red Butter Bolete is large and easily recognizable by its beautiful colors -- the combination of red, yellow and blue (discolorations) create a unique palette.  This taxon is pretty widely distributed in Europe, but in North America it only appears in California and the warmer parts of the Pacific Northwest. It's habitat is also a bit of a puzzle, as it may point to more than one species. In the coastal areas it fruits abundantly under Oak, while in the montane areas seems to like Fir. There is another similar taxon in California, also in section Appendiculati that currently is called Boletus appendiculatus, a name which is clearly misapplied -- it is separated mainly on the basis of cap color, but that is not convincing at all. Another related species is Boletus abieticola, which can be distinguished on the basis of the scales of its pileus. As a general note, the Butter Boletes of California need to be critically re-examined utilizing contemporary methods.