Observation 167659: Agrocybe Fayod

When: 2014-06-14

Collection location: Morton Arboretum, Lisle, DuPage Co., Illinois, USA [Click for map]

Who: Rocky Houghtby

Specimen available

Beneath spruce, binding litter, in an arboretum.

1.5cm, Broadly convex to campanulate, rugose, becoming radially aerolate, bright tan to brown, not hygrophanous, tissues thinner at the margin.

Attached with a notch, grey-brown.

3cm, longitudinally striate, basal mycelium binding litter, no rhizomorphs observed, veil membranous, fragile.

8.9 X 5.1, color not changing in KOH, germ pore less than .5 micron, cell wall .35 micron. Measurements taken from spores on partial veil and stipe apex.

1,2,3,4 spored basidia all observed, mostly clavate, some cylindrical.

Gill edge sub-homogenous, containing basidia and some cystidia identical to those found on the gill face, gill edge differing from gill face by short, subglobose terminal elements, sometimes with minuscule nodulose to digitate protrusions, some cheilocystidia narrowly lagenform with a sub-capitate apex, rarely with one or two short nodulose to digitate projections, some cheilocystidia appearing narrowly utriform. all cystidia near gill edge darkening in KOH more readily than further up the gill towards the pileus.

Very abundant, versiform, ranging from broadly utriform to lagenform with a constricted apex to very broadly lagenform with an obtuse apex, sometimes digitate to the point where the cell bifurcates.

All tramas observered to be interwoven with varying degrees of cell inflation.

A derm, hyphae strongly interwoven, many terminal elements clavate but no cystidia observed, distinctly brown and differentiated from the hyaline trama.

No cystidia observed, though many terminal elements clavate to basidiform, numerous branching hyphae with clamps present.

Specimen minuscule and observer skeptical of taxonomic significance, did not observe.


I probably will not be collecting anymore Agrocybe this year, as the Genus is primarily vernal in N. Illinois, so I would like to make a few brief observations. I believe I have observed five morphologically and microscopically distinct species in a plot area encompassing Lake and Cook counties; A “praecox” type, an “acericola” type, a “molesta” type, arvalis, and this species, which keys out around arvalis, but differs from that species in stature, lacking a hygrophanous pileus, possessing a temporal veil, basidia types and location on gill edge, cystidia shapes and hyphal system in the stiptipellis.



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Add Comment
By: Rocky Houghtby
2015-05-18 10:12:29 CDT (-0400)

I fear I wasn’t very clear about the ambiguity of the partial veil. I was not, and am not certain that the material on the apex of the stipe isn’t just the stiptipellis lifting off of the stipe. The specimen is clearly very dry, and there is evidence of cracking and areolation further down the stipe.

Hi Claude
By: Rocky Houghtby
2015-05-18 10:09:30 CDT (-0400)

I would hesitate to describe any of the cystidia in this collection as chrysocystidia, as there was no appreciable reaction in koh, or evidence of internal crystallization. Although, there is clearly some sort of refractive inclusion in the utriform and lagenform cells. I will revisit this observation in the future, when I have the capability to extract and sequence genetic material.

Hi Rocky
By: Claude Kaufholtz-Couture (Claude Kaufholtz-Couture)
2015-05-18 09:50:31 CDT (-0400)

Bitter taste ?
Pleurochrysocystides in A. arvalis ?
For my part, I have not seen.

That is why
By: Byrain
2014-06-18 09:45:50 CDT (-0400)

They included an alternative key, it certainly doesn’t end up there if you ignore the annulus in that one.

By: Rocky Houghtby
2014-06-18 08:51:53 CDT (-0400)

Is the first thing you land on if you exclude the veil, which was exceptionally fragile.
Thanks as always for your input, Byrain.

By: Byrain
2014-06-18 02:11:17 CDT (-0400)

How did you key this out around A. arvalis? The absent (reduced/non-visible) germ pore takes this to around A. cylindrica & A. erebia, but those have larger spores. In the alternative key it gets stuck at:

“12. Annulus present; spores on average 10.0–13.0 × 5.0–6.5 μm; pleurocystidia present; at least some of cheilocystidia clavate
12. Annulus lacking; spores on average 6.5–9.5 × 4.0–6.0 μm; pleurocystidia usually absent or scattered, if present lageniform”

The first which leads to the same at the other key and the seems to point to A. pusiola which is also small with similar spores, but this has a veil and no pileocystidia. I don’t think this species is included in fan6…

Created: 2014-06-18 00:07:47 CDT (-0400)
Last modified: 2015-05-18 14:24:00 CDT (-0400)
Viewed: 144 times, last viewed: 2018-01-10 15:04:11 CST (-0500)
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