Observation 95187: Hymenopellis megalospora (Clem.) R.H. Petersen

When: 2012-05-20

Collection location: Kahite Trail, Vonore, Tennessee, USA [Click for map]

35.5618° -84.2371° 256m

Who: Christine Braaten (wintersbefore)

Specimen available

Large bright yellow Hymenopellis. On soil under well decayed hardwood log, mixed hardwood forest.
Stipe length aprox 33 cm
Cap diameter 8 cm

Proposed Names

61% (2)
Recognized by sight
64% (5)
Eye3 Eyes3
Recognized by sight: glabrous stipe
Used references: Petersen, R.H. and Hughes, K.W. (2010) The genus Xerula. Nova Hedwigia Beiheft 136. J. Cramer Publ. Stuttgart 625pp
Based on microscopic features: spore characters, utriform pleurocystidia

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
I agree
By: Christine Braaten (wintersbefore)
2012-05-24 20:08:01 CDT (-0400)

that there is alot of variation, and macroscopically, this gigantic golden Hymenopellis is very distinctive so it certainly warrants some further discussion.

Size matters
By: walt sturgeon (Mycowalt)
2012-05-24 19:39:34 CDT (-0400)

or maybe not. I have seen this golden one get very large. What puzzles me macroscopically is that I don’t see any intergradation in color with “typical” H. megalospora.

yellow-capped “Xerula”
By: Dan Molter (shroomydan)
2012-05-24 19:23:11 CDT (-0400)

I found a similar mushroom here:

observation 23330

The golden yellow cap is pretty distinctive.

By: Christine Braaten (wintersbefore)
2012-05-24 16:52:18 CDT (-0400)

Thanks for your reply. Dr. Petersen and Dr. Hughes globally monographed this group, the book was published in 2010, and the GSMNP and the southeast was sampled pretty densly so the Hymenopellis complex is well resolved here in the southeatern US. I brought this particular specimen in to Dr. Petersen and he had me verify a few microscopic characters and expressed that this was a likely the golden variant of Hymenopellis megalospora. It is my understanding that the yellow coloration in the cap does not reflect significant genetic variation so as to suggest that it is a different species.

By: walt sturgeon (Mycowalt)
2012-05-24 13:09:23 CDT (-0400)

While the color of H. megalospora may have yellowish tones, it is in my opinion never this yellow. Kuo’s description: Cap: 2-8 cm; convex or broadly conical when young, becoming broadly convex to flat in age; fairly smooth, or wrinkled in a zone around the center; greasy in normal weather conditions; pale grayish brown to buff or nearly white; the margin often uplifted in maturity.
This yellow variety shows up occasionally in Ohio and southward. Another MO obs:
As far as I know we do not have a good name for this one.

By: Christine Braaten (wintersbefore)
2012-05-24 10:54:02 CDT (-0400)

Why doubtful on Hymenopellis megalopsora?

Spore size
By: Christine Braaten (wintersbefore)
2012-05-24 00:33:17 CDT (-0400)

Spore size was approximately 20 × 13 microns and at 100x were citriniform and dimpled.

There are six species of Hymenopellis known from the Eastern United States and this specimen is not H. rubrobrunnescens, H. incognita, H. limonispora, or H. rugosoceps.

The stipe was not furfuraceous or scabrous, so H. furfuracea is not likely.

Proposing H. megalospora as cap color is variable in this species, cap was viscid, utriform pleurocystidia were present.

Wondering about the average size of the spores
By: Jay Justice (Arkansas Traveler )
2012-05-21 07:31:37 CDT (-0400)

Can you give the group an idea of the size of the spores on this collection?

Created: 2012-05-20 22:05:41 CDT (-0400)
Last modified: 2012-05-24 19:34:09 CDT (-0400)
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