Observation 104514: Psathyrella (Fr.) Quél.

When: 2012-08-07

Collection location: Ricketts Glen State Park, Pennsylvania, USA [Click for map]

Who: Dave W (Dave W)

No specimen available

I suppose someone will object to my “I’d call it that” for this Psath. It represents one of two typical robust rugulose cap varieties reported for eastern NA.

Proposed Names

66% (4)
Recognized by sight
Based on microscopic features: small spore variety.
83% (1)
Recognized by sight

Please login to propose your own names and vote on existing names.

Eye3 = Observer’s choice
Eyes3 = Current consensus


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Just checked the monograph for P. rugulosa.
By: Dave W (Dave W)
2012-08-09 22:37:59 PDT (-0700)

(Actually, I had forgotten about the online Psathyrella book that I bookmarked on my computer.)

P. rugulosa is known from only one collection made in Tennessee, which is not all that far removed from Pennsylvania. But this one collection was made on conifer wood (spruce). My collection seen here was made in a forest where most of the trees are hardwoods, no spruce. The spores of P. rugulosa turned a tawny color when mounted in KOH. The dark-colored spore pic seen in this obs is a KOH mount. So I strongly doubt my collection represents an example of P. rugulosa.

It would be very cool if my collection was the rare species P. rugulosa. If I have decided to call some mushroom by some name, I don’t mind checking for a few other possibilities suggested by knowledgable folks such as one tends to find here on MO. In the past I have occasionally changed my mind about “I’d call it that”, and I’m pretty certain this will happen again in the future. But I simply do not have the time to read an entire catalogue of monographs as part of arriving at one ID.

IMO it is sometimes acceptable to propose “I’d call it that” without having read every monograph within the relevant genus. There are plenty of posts made here at MO that appear to fall into this category. Some genera are more difficult than others, and Psathyrella seems like a challenging one. But there are typically at least a few species within any given genus that are regionally realtively easy to ID. When I post Psaths to MO, I generally do not propose a confident species ID… with a few exceptions: delineata, rugocephala, candolleana, conissans (unusual spore print color for Psath).

The word “prove” does not apply in this setting.
By: Dave W (Dave W)
2012-08-09 13:42:27 PDT (-0700)

We may only hope to verify these types of claims. In this specific instance, it is my understanding that this eastern NA robust wrinkled-cap variety of Psath comes down to two possibilities for the species ID, P. delineata or P. rugocephala. The spore size of the collection seen in this obs strongly supports P. delineata. The comments seen within the following linked post support my claim.


I just did an internet search on Psathyrella rugulosa, and the sites which came up (inlcuding MO) offered next to nothing in the way of information on this speies. If this an eastern NA species?

I look at a lot of stuff that I bring in from the local woods, and from my own property. When the collection ID is sufficiently ambiguous to justify my spending time and energy doing things like looking at cystidia, then I consider making the investment. When the collection represents a well-known common type, I don’t bother.

My tongue in cheek comment was not meant to be an insult.

You have a microscope…
By: Byrain
2012-08-09 10:04:54 PDT (-0700)

Can you please look at the cystidia? If this is P. delineata pleurocystidia should be abundant, the shape is also distinctive. Plileus color mounted in KOH, what type of wood its growing on, and more specific spore sizes will help. Another species that you should consider is P. rugulosa which also has a conspiciously radially rugulose pileus, I wouldn’t say that is the only other species worth considering. The keys are impossible to navigate with the limited info you have provided.

Also, your self-fulfilling prophecy of someone coming to object is kind of insulting, especially when you made next to no effort to prove your id.

Created: 2012-08-09 08:25:17 PDT (-0700)
Last modified: 2012-08-09 15:33:57 PDT (-0700)
Viewed: 93 times, last viewed: 2017-06-13 09:08:31 PDT (-0700)
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