Observation 34913: Psathyrella senex (Peck) A.H. Sm.

When: 2010-02-12

Collection location: Los Trancos Preserve, Palo Alto, California, USA [Click for map]

Who: Douglas Smith (douglas)

Specimen available

Found on the bark of live oak trees.

This id doesn’t seem bad, but with Psathyrella it never seems to leave you with a comfortable feeling.

The first micro-shot is of the gill edge at 400x in KOH. Here the cheilocystidia are lageniform, some inflated, mostly with blunt apecies, a few with inflated to subcapitate apecies. Numerous pleurocystidia were also seen, similar to cheilocystidia. 2-spored basidia were obs.

The second micro-shot is of the cap surface at 400x in KOH. Here the cap surface is a cellular epithellium, with no gelatin or pileocystidia obs.

The third micro-shot is of the stipe surface at 400x in KOH. Here the caulocystidia can be seen, mostly lageniform, with some globose elements.

The forth micro-shot is of spores from the stipe apex at 1000x in KOH. The spores are ellipsoid, grey-brown, smooth, thick-walled, with a small germ pore. The germ pore is quite small on these, less than 1um. Ave spore size : length – 7.59 +/- 0.60 (err 0.15) um, width – 4.73 +/- 0.27 um (err: 0.08) – q : 1.61 +/- 0.10, on 17 spores.

So, looking in the monographs, actually in the Smith monograph it suggests these might be P. obsutata, but that didn’t quite seem right. It seems these should have a shaggy veil, but only when quite young. There is some veil fragments on margin on the younger ones, and these go away in age.

With that, then they get to a better place with P. senex. This is also the id in the keys in Funga Nordica and Kits van Wavern, so it looks like a fairly good id. It is mentioned that these are fairly rare in Europe, but more common in North America. The type location is upstate New York with Peck, but Smith found them quite often it seems in Michigan. He mentions an id from Idaho, so he thought they were in the western US also. So, this id looks fairly good.

Then again, it isn’t like there is going to a lot of people looking at Psathyrella that are going to disagree with me…

Sorry about the first photo, it was pretty dark where I found these on the live oak bark…

Proposed Names

86% (1)
Eye3 Eyes3
Recognized by sight
Used references: “Psathyrella of North America,” A. H. Smith; “Psathyrella of British Isles” Kits van Wavern; Funga Nordica
Based on microscopic features: lageniform and inflated cheilocystidia and pleurocystidia, spores 7-8um long with very small germ pore, gregarious on hardwoods.

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Created: 2010-03-19 13:31:52 CET (+0100)
Last modified: 2010-03-19 13:31:52 CET (+0100)
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