Observation 76637: Gastroboletus Lohwag

very mature specimen. growing in soil near Red Fir. YNP 2200

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note that context turned yellow after initial cut, as pictured on log

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Starting to look like Gastroboletus
By: David Rust (incredulis)
2011-09-23 17:26:50 CDT (-0500)

Nhu Nguyen at UC Berkeley took a look at the spores as well. This may be something new. I’m hoping Tom Bruns Lab will run DNA on it, then we’ll know more.

Spores not wide enough
By: Daniel B. Wheeler (Tuberale)
2011-09-23 17:20:56 CDT (-0500)

to be considered Gautieria, as both G. monticola and G. parksiana are several microns wider. But spore length fits well. In my experience, Gautieria are more likely to have a semblance of columella, but not as profound as this collection has. The peridium of Gautieria is often eroded or worn away quickly with any handling. In sandy soils any remnant of peridium might be destroyed during normal maturation.

Guess I need to break out How to Know the Genera.

The spores are too large to be among the Rhizopogon,
By: Daniel B. Wheeler (Tuberale)
2011-09-23 17:12:42 CDT (-0500)

so I think that large genera can be removed from consideration.

The range for G. subalpinus is given as 10-18 × 4.5-8 microns, in NATS Field Guide, so it certainly could be in that genus. However, according to that source it is always hypogeous (underground) and has a distinct reduced stem plus remnants of a cap cuticle should be present.

So, if this is a Gastroboletus, is is likely one of the rarer species or possibly (probably?) a species novum.

A note on this specimen
By: David Rust (incredulis)
2011-09-23 12:30:17 CDT (-0500)

We took half of this specimen to Dr. Dennis Desjardin at SFSU, and he took a look at the spores:

The taxon with the yellow columella looked to me to be an old Truncocolumella citrina specimen with the outer peridium eaten up by bugs (it was rather sandy, buggy and old). The spores, however, are wrong for Truncocolumella and more bolete-like (subfusoid, inequilateral, apparently ballistosporic, about 11-13 × 5.5-6.5 µm, yellowish brown in KOH), and the basidiome appears to not have a peridium.

If with elongated ridges on the spores …
By: Daniel B. Wheeler (Tuberale)
2011-09-21 21:54:30 CDT (-0500)

could be Gautieria pterosperma, which is known from CA as late as September. I’ve never seen a Gautieria with such a well-defined columella before. But there’s lots of things I haven’t seen, too.

mature specimen
By: David Rust (incredulis)
2011-09-21 19:36:41 CDT (-0500)

I almost didn’t collect this one because it was so soft and spongy. I really thought it was rotten. Debbie photographed it later and it had more blueing. There was no evident peridium. It’s been dried at UC Berkeley and they will run DNA on it eventually.

Blue staining and loculate interior confirmed.
By: Daniel B. Wheeler (Tuberale)
2011-09-21 18:56:20 CDT (-0500)

When I blow the second photo up to large size, can see some bluing near columella, and even some aqua-blue in the gleba near the columella. As the locules appear surrounding everything except the extreme bottom of the sporocarp, nearly certain it has to be Gastroboletus.

Glad you saved the specimen in herbarium. Consider sending half the collection, including copies of the photos and a link to this thread to NATS at Corvallis, OR. I know Matt Trappe was working on identification now, but don’t have is current address or contact information.

According to Field Guide to North American Truffles, Gastroboletus subalpinus is at least similar, but should have a distinct and easily identifiable stipe, usually pointed toward the base. This collection looks more like the stipe has become totally internalized, and therefore likely presents a separate species.

There are 2 things which cause me to question Gastroboletus. 1) No apparent separate cap; 2) no obvious stipe.

The appearance forces me to consider Gautieria as well, but have no microscopy to compare with. The soil-covered (or is that humus?) sporocarp does resemble a Gautieria more than a Gastroboletus. But we still don’t know if this collection was found hypogeous (under humus, not exposed) or epigeous (exposed to air, erumpent, above ground).

David, you say this is a “very mature specimen”. Why did you state it was very mature? Did it have a strong odor? Had an animal already uncovered it?

There is blue staining and pore-like spore-bearing openings
By: Christian (Christian Schwarz)
2011-09-21 18:27:05 CDT (-0500)

The blue staining can be seen in the first photo well.

Any microscopy?
By: Daniel B. Wheeler (Tuberale)
2011-09-20 23:43:37 CDT (-0500)

I’m wondering how Gatroboletus was derived. There is no color changes that I can see. Stipe instead of columella? Maybe? Was this totally epigeous or partially hypogeous? Growing in soil near Red Fir. Is that Shasta Red fir? Or are there multiple Red fir in CA?

I’m not convinced this is Gastroboletus. But I’m hard-pressed to guess what it is.

Created: 2011-09-19 12:16:59 CDT (-0500)
Last modified: 2011-09-19 12:17:01 CDT (-0500)
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