Genus: Boletus (will probably change – see Science Notes)
- Genus 2: Likely to become Suillellus
Species: discolor (will probably change – see Science Notes)
- Species 2: erythropus ssp. discolor
- Species 3: luridiformus ssp. discolor
Tells: Cap bruises black. Blue-staining, orange-red pores age yellow from the edge in. Yellow stem w/ fine red-brown dots stains blue-black or browns w/age.
Other Information: Pale yellow flesh quickly blues. Cap color starts orangey, fades toward yellow, and then darkens to brown from the middle out. A common species from the Mason-Dixon line up. No netting distinguishes from B. luridus, & no red hairs at the stem base distinguishes from B. subvelutipes. B. luridiformis has a darker cap and darker yellow flesh than B. discolor, but chemical tests are required to conclusively distinguish the two (they have distinctly different reactions to Ammonia and KOH).
Science Notes: The European species formerly known as Boletus discolor and Boletus luridiformis have been merged into a single species that is now called Sutorius (f/k/a Neoboletus) luridiformis. (Boletes of Eastern North America follows this by merging the American “discolor” into “luridiformis,” using Neoboletus as the genus). Here’s the problem: the North American mushrooms known by those species names are almost certainly different from their European counterparts, and there is no solid reason (yet) to merge them – especially since the two are reported to have different reactions to both Ammonia and KOH. For this reason both discolor and luridiformis still appear here under their old (and no doubt soon to change) names. Stay tuned for new developments. Heck, we do not know even whether this spectrum is a single species, varieties of other species, or a species complex! But we do know that the research is proceeding.
We have kept “discolor” in Boletus for now because that is the accepted “grab bag” and there is not enough evidence to move it inot another genus. One hopes the science will catch up to both of these, along with the other hard-to-distinguish red pored, blue staining lookalikes such as B. subvelutipes, B. subluridus, B. subluridellus, and B. flammans, not to mention the one now known as Suillellus luridus, the several moved to Rubroboletus, and the brown-pored blue-stainers vermiculosus and vermiculosoides.
Edibility: The traditional instruction in America was clear: “Avoid the red-pored blue-stainers like this one because they are known sick makers.” That came under question beginning in the 2010’s as DNA evidence proved that these mushrooms are quite distinct from the Rubroboletus and Suillellus genera that contain the true “Satans Boletes”. For what it’s worth, the lookalike European mushroom called luridimormis/discolor is a highly prized edible commonly known as the Scarletina. So it comes down to your taste for adventure and your respect for received wisdom.
- NH4OH (Ammonia): Cap surface yellow changes to dark slate and darker areas change to rusty brown. Cap flesh loses its blue staining.
- KOH: Cap surface (and stem) turns blood-red to rusty brown. Cap flesh turns orange to orange brown.
- FeSO4 (Iron Salts): Cap surface turns olive, but stem has no reaction. Cap flesh turns greenish olive.