Observation 58035: Xerocomellus dryophilus (Thiers) N. Siegel, C.F. Schwarz & J.L. Frank
When: 2010-11-03
No herbarium specimen

Notes: Spores fusiform and ellipsoid, not truncate. Under coast live oak.

Spores 11 – 14 × 5 – 7 microns.

Proposed Names

-48% (2)
Recognized by sight: Under coast live oak. Staining blue a little. Red stem, yellow at apex.
Based on microscopic features: Spores truncate.
38% (3)
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
By: Christian (Christian Schwarz)
2010-11-05 19:51:02 CST (-0500)

To Alan & Debbie – a good theory discussion and better species concepts. Best of both worlds.

By: Alan Rockefeller (Alan Rockefeller)
2010-11-05 19:24:12 CST (-0500)

Glad someone was paying attention. I put the correct spore pics in this observation.

don’t be sorry…
By: Debbie Viess (amanitarita)
2010-11-05 19:20:08 CST (-0500)

it was a fun little ID rumble.

Sorry about the spores
By: Alan Rockefeller (Alan Rockefeller)
2010-11-05 19:07:54 CST (-0500)

After reading the comments I put this sample back on the scope and saw that the spores definitely are not truncate. I collected several Boletus samples and they somehow got switched. The spores are both ellipsoid and fusiform, perhaps dependant on which direction they are facing. They measure 11 – 14 × 5 – 7 microns.

were your micrographs taken at 1000x, Alan?
By: Debbie Viess (amanitarita)
2010-11-05 12:35:42 CST (-0500)

If so, those spores are too small to be truncatus (measured by Thiers at 12-15 micrometers in length), and frankly not so clearly truncate, either, at least to my eye, altho some do appear to be blunted.

The macro is indeed a better match for dryophilus, with the stipe yellow rather than red at the apex, as well as that reddish not brown cap…\

Oh, and I just read your bluing notes…truncatus blues instantly and strongly. I’m throwing my vote in with dryophilus.

ah, the trouble with changing modes of taxonomy…
By: Debbie Viess (amanitarita)
2010-11-05 12:30:49 CST (-0500)

Christian sez: “Of course, there are cost, accessibility and quality issues with DNA sequences…”

Ya think? ;)

Funny, for years the prevailing argument was that micro features are static and dependable, while macro are mutable, therefore you can only trust the micro, in a clinch…now DNA is getting touted as the ultimate answer to everything.

Personally, I just think that the mushrooms are messing with us! Stirrin’ up us order loving humans and helping to keep us humble! I’d say it’s the fungi who have the last laugh.

I dunno…
By: Christian (Christian Schwarz)
2010-11-05 12:04:29 CST (-0500)

Does it?

It could be looked at the other way – the only fly in the truncatus ointment is the fruitbody color.

I don’t think we’ve done enough work to say that micro features necessarily trump macro features. It is almost certain to vary between genera.

There are three basic approaches to macrofungal ID: molecular, macro morphology, and micro morphology. Since micro and macro discrepancies often leave us at a dead, we need to use sequence info as a tiebreaker.

Of course, there are cost, accessibility and quality issues with DNA sequences…

the only fly in the dryophilus ointment…
By: Debbie Viess (amanitarita)
2010-11-05 11:24:14 CST (-0500)

are those truncate spores. Dryophilus doesn’t have ’em, according to Thiers.

Otherwise, macroscopically, habitat, location etc., does look like dryophilus.
But doesn’t micro trump macro?

That looks
By: Christian (Christian Schwarz)
2010-11-05 10:06:29 CST (-0500)

like B. dryophilus – strongly red cap and stipe. From my experience B. dryophilus is one of the most common boletes in San Diego.

Created: 2010-11-05 01:26:11 CST (-0500)
Last modified: 2014-07-23 13:54:42 CDT (-0400)
Viewed: 118 times, last viewed: 2016-10-24 12:45:27 CDT (-0400)
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