Observation 71853: Mycena overholtsii A.H. Sm. & Solheim
When: 2011-07-16
No herbarium specimen

Notes: A snowbank mushroom, growing under spruce at ~3000m elevation. Caps 2.5cm, stem 40×2mmm. Spores 7-10 × 3-3.5 microns. No cystidia observed. The spore shape suggests Collybia/Gymnopus?

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By: Sava Krstic (sava)
2011-07-20 20:47:41 PDT (-0700)

Thanks for the comments.

There were only two of these mushrooms and they seem to be terrestrial; with large parts of the stem in the ground. I added pictures showing the spruce details and the snow nearby.

The subtle thing
By: Christian (Christian Schwarz)
2011-07-19 11:50:59 PDT (-0700)

is that narrowly elliptic becomes pip-shaped when you take into account the hilar appendage – the little snouty bit – some authors disregard it entirely in their description, others factor it out more cautiously. I agree that it isn’t as clearly elliptic as a typical Clitocybe spore, but you have to account for idiosyncracies of the people doing the description.

It’s be nice if someone had photos of the spores of this species for comparison… the original article isn’t online.

were these growing on conifer wood?
By: Debbie Viess (amanitarita)
2011-07-19 10:17:39 PDT (-0700)

and were there more than just these two fruit bodies? overholtzii commonly grows in densely cespitose clusters on wood at snowmelt…they are NOT terrestrial.

here is a California description for the spores: narrowly ellipsoid, smooth, thin-walled, amyloid, typically collapsed in dried material. if overholtzii, they should show cheilocystidia but not pleurocystidia.

the spores that you show are lacrymoid (subcylindric with suprahiloid depression).

By: Drew Parker (mycotrope)
2011-07-19 09:59:02 PDT (-0700)

These are narrowly pip shaped, and that is how Maas Geesteranus describes spores of M. overholtsii. Smith says they are pip shaped when immature.

By: Sava Krstic (sava)
2011-07-19 08:58:47 PDT (-0700)

It’s hard for me to see these spores as elliptic. “Elliptic” implies two axes of symmetry. These spores are distinctly curved; all of them. In Largent’s “How to … , no. 3”, spores like this are called pip-shaped.

No, I’d call those elliptic
By: Christian (Christian Schwarz)
2011-07-19 08:42:58 PDT (-0700)

maybe long-elliptical.

Noah, Drew
By: Sava Krstic (sava)
2011-07-19 08:38:35 PDT (-0700)

Thanks for the ID and comments.

The reagent used was KOH + Congo Red.

M. overholtsii (which I’ve never collected) is supposed to have elliptic spores, and the spores in my picture have a different shape, don’t they?

By: Drew Parker (mycotrope)
2011-07-19 06:50:55 PDT (-0700)

M. overholtsii looks likely, but what reagent would turn the white spores orange-brown? Spores should be amyloid for overholtsii, so if it’s Melzer’s there is a problem.

Created: 2011-07-18 23:33:31 PDT (-0700)
Last modified: 2011-07-19 16:10:13 PDT (-0700)
Viewed: 144 times, last viewed: 2016-10-25 11:57:54 PDT (-0700)
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