Observation 70102: Tylopilus rubrobrunneus Mazzer & A.H. Sm.
When: 2011-06-24
No herbarium specimen

Notes: Growing in the same spot in my front yard (nearby a wood border… pine, hickory, oak) during any late spring or early summer that features lots of rainfall.

Only thing that doesn’t check exactly is that the spores are a little longer than the size reported in B/R/B. Stipe is finely reticulate at apex. Stipe bumpy with depressions in mid section. White basal mycelium.

First and second photos taken several days (and several inches of rainfall) apart.

Proposed Names

13% (3)
Recognized by sight: …and by the bitter taste.
Used references: North American Boletes
Based on chemical features: Cap very pale yellow in KOH, negative on context.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Although the KOH reactions…
By: Dave W (Dave W)
2014-04-04 22:37:46 PDT (-0700)

seem to support violatinctus, I think that spore size is a more reliable way to separate this species from rubrobrunneus. The spores seen here are over 10 mu (correction of +17% to scale as seen).

I find lots of these large purplish Tylos in the same spot every summer. KOH reaction, especially on the cap surface, varies. But I have yet to see the “pinkish” tinge that B/R/B reports for rubrobrunneus. Sometimes I get a fairly vivid mustard-yellow KOH reaction on the cap. Interestingly, one person who observed the KOH reaction on a cap saw a pinkish tinge, despite both my wife and I seeing the yellow. So maybe there’s a subtlety in color perception going on here. This summer I hope to match the reaction color to the Online Auction Color Chart.

Results of KOH application
By: Dave W (Dave W)
2011-06-25 07:15:52 PDT (-0700)

are way off for rubrobrunneus. Stipitipellis negative with KOH (as opposed to “mahogany red” as reported in B/R/B), and the cap cutile turns pale yellow in KOH. Pore surface darkens a bit in KOH… looks like just on account of becoming wet.

Maybe it’s neither rubro or viola?

Created: 2011-06-24 23:32:12 PDT (-0700)
Last modified: 2014-04-04 22:22:04 PDT (-0700)
Viewed: 85 times, last viewed: 2016-10-24 08:35:54 PDT (-0700)
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