When: 2011-09-17

Collection location: Yosemite National Park, California, USA [Click for map]

Who: Douglas Smith (douglas)

Specimen available

Found under white fir, and pine.

Part of the Yosemite National Park Fungal Survey, num. YNP1918.

No parts stained blue at any time.

Species Lists


Proposed Names

29% (1)
Recognized by sight
91% (2)
Recognized by sight
Based on microscopic features: IDed by Dennis Desjardin…compared to type.

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= Observer’s choice
= Current consensus


Add Comment
From what I see… and more…
By: Dimitar Bojantchev (dimitar)
2011-10-07 21:04:20 CDT (-0500)

it is the spore wall that seems to react slightly amyloid – in general it is the spore wall that reacts to Melzer’s in the various genera, when it does.

But see, the part that both intrigued me and concerned me greatly is how we use this character – spore wall chemistry is a very, very basal character that does not change behavior from one species to the next.

So, I checked 2-3 more boletes from my collections – B. frustosus, B. “rubripes”, etc. and they all showed a slightly amyloid spore wall reaction!!!

Interestingly, Smith and Thiers have a this informative line from the “Boletes of Michigan”:

“Recently, it has been found that spores of boletes may give a bluish reaction in Melzer’s, but this feature is not as clear as in the agarics because of certain complications, the first being the rather highly colored spore wall. This obscures the reaction. It has also been found that spores taken from dried hymenophore tissue are dingy blue mounted directly in Melzer’s but soon change to reddish tawny (dextrinoid) in at least the distal half of the spore, the proximal half merely fading to yellowish. This reaction has been termed a “fleeting-amyloid”

I believe that to be correct and applicable to a broader set of species in the genus… for the reasons stated baove.


some of the Gastroboletes have spores that partially turn blue…
By: Debbie Viess (amanitarita)
2011-10-07 19:21:08 CDT (-0500)

I think that amyloideus changes completely, not just on the spore wall.

This is a very strange species
By: Dimitar Bojantchev (dimitar)
2011-10-07 17:16:48 CDT (-0500)

Quite common in the high Sierra under Lodgepole pine and red fir. I just looked at my collections – the spore walls do appear amyloid indeed. One can see it on the slide photo too. The spores are also a bit strange, although that I likely have immature fruitbodies. I tasted it though, not bitter. I’d love to see some phylogeny on this critter. I suspect it is on its own branch somewhere…

just a slip of the tongue/typing finger…
By: Debbie Viess (amanitarita)
2011-10-05 12:12:17 CDT (-0500)

no worries.

nice to have a type specimen to compare it to, but isn’t it the only Gastroboletus in CA that has fully amyloid spores?

By: Douglas Smith (douglas)
2011-10-04 17:28:43 CDT (-0500)

Right, I meant that… I was looking at the Boletopsis obs. from Yuba pass just before posting this comment. Yes, I meant Gastroboletus, not Boletopsis…

that makes a lot more sense!
By: Debbie Viess (amanitarita)
2011-10-04 17:18:33 CDT (-0500)
this wasn’t saved?
By: Debbie Viess (amanitarita)
2011-10-04 17:16:58 CDT (-0500)

I don’t remember seeing it…

Why Boletopsis?

This one…
By: Douglas Smith (douglas)
2011-10-04 16:07:05 CDT (-0500)

This one was found also at Yuba Pass this past weekend by Dennis Desjardin. It had the same yellow and red colors, and also refused to stain blue when bruised or cut. At the time it was recognized as a Boletopsis, but it was unknown as to which species.