under coast live oak.


note reddened pore surface.

Proposed Names

-86% (1)
Recognized by sight: one of the cryptic species within the regius group. both bright yellow pore surface and yellow reticulations redden, making this species unique. Will get a new name in the upcoming butter bolete paper by Jonathan Frank and David Arora.
Used references: Jonathan Frank.
Based on chemical features: mild flavor.
38% (2)
Recognized by sight: red-capped butter bolete under live oak. pore surface reddens.
Used references: Mycologia. 2014 May;106(3):464-480. Epub 2014 May 28.
Clarifying the butter Boletes: a new genus, Butyriboletus, is established to accommodate Boletus sect. Appendiculati, and six new species are described.
Arora D1, Frank JL2.

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= Observer’s choice
= Current consensus


Add Comment
By: Roy Halling (royh)
2014-06-18 15:18:13 CDT (-0400)

likely too old.

if Noah is referring merely to stature …
By: Debbie Viess (amanitarita)
2014-06-18 15:12:59 CDT (-0400)

then yes, the photos of tomentipes, even in its desiccated state, appears to have a fairly thick vs slender stipe. but of course, there is always variability, like in this thick-stiped X. truncatus sighting here:

too old for DNA testing?

Not so far out
By: Roy Halling (royh)
2014-06-18 14:15:16 CDT (-0400)

on a limb. Noah might have a good hypothesis (not a theory), but in 113 yr, nobody else has even tried to make a stab at it. It’s easier to acknowledge that it was published and then just ignore it.

out on a limb …
By: Debbie Viess (amanitarita)
2014-06-18 12:58:58 CDT (-0400)

easy to check dessicata for reticulations if you hold it in your hand.

not so easy to photo ID a dried lump of bolete flesh to genus, from across the country.

here is what Noah was using to make his theoretical determination:

back to reality, folks.

Lookign at the pictures of
By: Noah Siegel (Noah)
2014-06-18 12:46:40 CDT (-0400)

the herbarium specimens of Boletus tomentipes it looks more like B. amygdalinus than a Xerocomid bolete…

home court advantage!
By: Debbie Viess (amanitarita)
2014-06-18 12:41:17 CDT (-0400)

good to see someone consulting an actual specimen rather than just spreading “rumors.”
(aka: a sighting w/out a specimen is just a rumor.)

at this point, we are chasing rumors in this ID.

It is a bit frustrating that these CA type specimens are in freakin’ NY, though, altho it sure worked for you, Roy! Thanks for sharing your findings here, and so quickly!

In the herbarium . . .
By: Roy Halling (royh)
2014-06-18 12:26:35 CDT (-0400)

which is where I went AFTER I made the comment (should have went there first). My Bad! I did look at the type specimen images on line, then I walked over to the other end of the building, and I used my hand lens on the 3 specimens, and could not see a reticulum. It is a big mushroom, and whether or not B. tomentipes is a Xerocomus or Xerocomellus still remains to be determined.

As far as white vs yellow context goes, I’ve been amazed by how often true context colors are ignored, and/or masked by oxidation reactions. Thanks!

reddish pores …
By: Debbie Viess (amanitarita)
2014-06-18 12:18:03 CDT (-0400)

from 2001 bolete collection, pre-camera.

But this brilliantly red-capped bolete is not a Xerocomellus, nor is it B. tomentipes as described in Thiers’ California Mushrooms.

Still, good to see other descriptions of those reddening pores.

By: Noah Siegel (Noah)
2014-06-18 12:08:38 CDT (-0400)

I read the B. tomentipes description a couple of years ago I thought Xerocomellus (X. truncatus group). Because of the stipe description “stipe cylindric, densely but minutely velvety-pubescent, sometimes becoming nearly glabrous above”. Xerocomus in CA have glabrous stipes.

And we all know that Xerocomellus pores are quick to go red sometimes.

By: Christian (Christian Schwarz)
2014-06-18 11:58:25 CDT (-0400)

Murrill’s notes don’t mention a reticulate stipe for what it’s worth. He does mention a velvety cap surface, and whitish context (not yellow as in a Butyriboletus).

My guess is that the description of B. tomentipes refers to a Xerocomus (Murrill considered it a Ceriomyces as with C. oregonensis, which is xerocomoid).

X. subtomentosus (in its complicated CA sense), can show reddish-brown discolorations on the pores. See observation 119602, observation 121167, observation 14805, and observation 61914 for examples.

Boletus tomentipes
By: Roy Halling (royh)
2014-06-18 11:39:10 CDT (-0400)

described by Earle from Stanford Univ collections (Nov 30, 1901) is described as having red-staining hymenophore. See Boletes of Calif., p. 68. Cap color as originally described might be “off” due to age (or not). On p. 69, Thiers says, “The brick-red discoloration of the tubes when bruised or dried is a most distinctive feature.” A former Sec Def said something about unknown unknowns . . .

By: Debbie Viess (amanitarita)
2014-06-18 11:04:11 CDT (-0400)

photo IDs from once remove are notoriously challenging.

reddened pores and reddened reticulation are obvious in the first photo; not sure why you don’t see it. Monitor trouble?

look for that poof of red pores at the bottom of the top fb; only part of the hymenium is reddened.

I only found a single specimen. I only discuss the actual observation depicted, in all of my sightings, unless I link to another obsie on MO.

in hand, the fb was indeed pale yellow on the stipe and in the context, the cap bright red, not chocolate brown.
yup, I have seen reddened pores even in Boletus truncatus/zelleri. Maybe it is just more common than we think, or is caused by environmental conditions? who knows?

like I said, I will look for this species again, and we will run the DNA. until then, it can just be a mystery.

here’s a thought, David … why not put up some typical forms of your newly named better with butter bolete species right here on MO as a reference point? that would be very useful to the rest of the myco-community.

Remember that lengthy discussion that we had back on the SOMA list a couple years back, around Cantharellus cascadensis? It resulted in many new observations of that species added here on MO, although sadly, none from you. Prior to that spirited SOMA discussion, there were almost no photos of cascadensis and very little general understanding of the sp. concept.

All of these debates help us to learn. All of us.
By: Mycoamaranthus
2014-06-18 01:56:54 CDT (-0400)

because the photos don’t show the characters you describe, and the chocolate tones on the pileus in the second photo are very uncharacteristic of butter boletes. If the photo colors are wrong and the colors you describe (pale yellow flesh, stipe) are based on this collection (unclear to me whether you are also including past collections from the same spot in your description), then Bu. autumni- or querciregius are likely candidates.

As for reddish pores and reticulation (another character I don’t see in the photo), there are many normally yellow-pored boletes that sometimes show a slight reddening of the pores, including Bu. persolidus, so this would not be surprising, albeit untypical, in Bu. autumni- or querciregius.

the case of the missing bolete!
By: Debbie Viess (amanitarita)
2014-06-09 18:02:14 CDT (-0400)

I looked in the most obvious places, and couldn’t locate a dried specimen. I know that I kept this one in my fridge for weeks, hoping that someone would take an interest. not sure that it made it onto my drier, a helluva lotta specimen shrooms pass thru my hands, and it is still possible that I just didn’t find it yet. There are too many places in this house where I store dried mushrooms!

can y’all relate?

At any rate. Alan Rockefeller offered to run the DNA on this one, so I did a thorough search. If it shows up here, I will send it to him, and the results will get posted here. Otherwise, I will check the exact location where I found this again next season: both fall and spring, since it really could be a normal fruiter from any season, this crazy year.

I appreciate the ways in which this bolete doesn’t fit neatly into the narrow querciregius concept, but there are morpho-outliers, so let’s just wait and see what the DNA tells us.

seems like we are still building our species concepts.
By: Debbie Viess (amanitarita)
2014-06-08 12:51:56 CDT (-0400)

I looked at your original paper on this topic, again. In your left-most photo of this sp., it clearly shows a BRIGHT red cap, that is fading to more yellow. My example here is much younger, and was partially covered in a dry spell, under canopy, so no rain/no sun to bleach the colors. After several days at home, it also faded, showing yellow tones and less vibrant reds.

Your photo from Mycologia also shows the reddish coloration on the stipe, and below that, a rather pale yellow, as do many other butter bolete photos from here and there, including MO and the butter bolete paper itself.

In other words, according to the photographic evidence, the stipe of a butter bolete is NOT always bright yellow.

Flash vs natural light will change the perception of that pore surface, but it IS bright, and the original description for querciregius also claims that the pore surface turns bright yellow:

“…Hymenophore (tube layer) pale yellow becoming bright yellow and eventually olive yellow or greenish…”

What was unusual to me was that red pore staining and the reddish reticulations on the stipe, which is why I wrote Frank to begin with, when I first collected this. It did NOT fit neatly into Thiers’ concept of regius!

I remember exactly where this was found, and said so on this sighting. Under oak, in the East Bay hills near my house.

I am pretty sure that I still have this; I would need to check. I admit to having a rather disorganized personal herbarium! If so, you are welcome to run the DNA for confirmation or denial.

The context was also typical, a very pale yellow with vinaceous staining at the base, similar to what is shown in sectioned butters in your paper.

More cryptic species underneath that regius umbrella? Maybe so, but obviously, if even the co-author of the butter bolete paper got it “wrong,” then maybe we are just not allowing for the inevitable variability within species?

I would be curious to hear what you think it might be instead.

By: Mycoamaranthus
2014-06-07 23:09:20 CDT (-0400)

I don’t visit MO often so I spent a little time going through some of the B. regius obs on MO and there are quite a few B. querciregius that can now be labeled as such. Here are three that show the typical coloration of pink or yellow cap and yellow stalk (sometimes, a blush of red also on the stalk): 29088, 28169, 15680. In some of the other obs the stalk shows as white rather than yellow, but this is common for photos of butter boletes when the photo is taken in deep woodland shade: yellow tones are often lost when the stem is overexposed in order to bring out good color in the cap. It is hard to say without more information what this particular specimen is; I have an idea but it is nothing more than an educated guess. It would be interesting to re-collect it if you remember the location.

By: Mycoamaranthus
2014-06-07 13:54:42 CDT (-0400)

querquiregius. I believe the author you refer to has only seen the species once. A butter bolete of any kind should have a bright yellow stem and this one does not. Querciregius has a much paler and differently colored cap. The pore color is also the wrong shade of yellow.

By: Debbie Viess (amanitarita)
2014-06-07 11:56:57 CDT (-0400)

the actual author of this species disagrees with you.

A picture
By: Noah Siegel (Noah)
2014-06-07 11:40:35 CDT (-0400)

of the flesh and staining of the pores (if any), would have be useful here.

Yes, species are variable… But it was that belief that lumped all red-capped Butters under the name regius.

Your specimen does NOT have the features of B. querciregius

yes, but nothing that will tell you anything more.
By: Debbie Viess (amanitarita)
2014-06-07 11:28:51 CDT (-0400)

the reddening reticulations and pores are typical for this sp., according to Frank.

every species is variable, including the human species. Just look at your handsome photo, here!

Do you have any more pics/info?
By: Noah Siegel (Noah)
2014-06-07 11:23:34 CDT (-0400)
Jonathan Frank didn’t think so…
By: Debbie Viess (amanitarita)
2014-06-07 10:47:20 CDT (-0400)

when I sent him the image a few month ago.

the only two Butyriboletus species under oak that redden on their pore surface are appendiculatus and querciregius. The red cap makes this querciregius.

This is strange for a Butter,
By: Noah Siegel (Noah)
2014-06-07 09:03:10 CDT (-0400)

and it’s most likely not B. querciregius. Cap too dark, stipe color is a little weird, reticulation too coarse.

Do you have more info, such as staining, flesh color, etc?

although this species more typically occurs in the fall …
By: Debbie Viess (amanitarita)
2014-06-06 12:59:14 CDT (-0400)

it has been infrequently collected in the spring by Arora. This year, we had simu-fruitings of both fall and spring mycoflora following our late March rains. Drought can cause ripples in our mushroom realities.

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