Observation 100194: Psathyrella rugocephala (G.F. Atk.) A.H. Sm.

When: 2012-07-13

Collection location: Hickory Run State Park, Pennsylvania, USA [Click for map]

Who: Dave W (Dave W)

No specimen available



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Eye3 = Observer’s choice
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Thanks Byrain. Your points are well taken.
By: Dave W (Dave W)
2012-07-16 16:14:59 PDT (-0700)

Suggesting alternative species IDs is potentially very helpful. I agree completely that the info found on MO is something that should be cherished. It should be well vetted.

Please bear with me as I attempt to address each of the species proposals which you put forth.

First, (beginning with the easiest for me to address) P. candolleana is very common; I have seen it many times. I do admit that this species is fairly variable, from the macroscopic perspective. But the caps are generally light colored, and the stipes rather thin… comapred to this obs. I seriously doubt this obs features specimens of P. candolleana.

I am not familiar with P. longipes. However, a quick internet search reveals this species is another typically slender Psath. I doubt my post represents this species.

Actually, I have personal history with P. longistriata. Please bear with me. My first encounter with MO was during a cold month of January (here in NE PA) when virtually no mushrooms are fruiting. My initial reaction to MO was, “Wow, lots of mushrooms to look at!” Well, those mushrooms were collected mainly from CA. So, in hindsight quite predicatably, my first several ID poposals were all obviously incorrect. (For me, CA is like an alternative fungal universe!) My first attempt at IDing a mushroom on MO was to call an example of P. longistriata “Tubaria confragosa.” Now as bad luck would have it, the specimen in question did resemble T. confragosa. But, to make a long story less long, it took the CA MO people a fair amount of effort to straighten the whole thing out… because the person who posted the obs initially thought my T. confragosa proposal had merit. From my perspective, the real problem was that I had never seen an actual example of P. longistriata. This species — like many others — does not occur in eastern NA. Additionally, and it is typically slender, as I understand the species concept.

So far, nothing put forth convinces me the mushrooms posted in this obs are anything other than P. delineata or P. rugocephala. Because these two species are the only two reported eastern NA species of Psath that fit the macro traits of this obs.

Still waiting on that scope upgrade. Thanks for the reminder, Byrain. I need to run this past my contact in the local Bio dept before I lapse into vacation mode… next week.

Rugulose caps
By: Byrain
2012-07-16 13:36:47 PDT (-0700)

I’ve searched rugulose in the Psathyrella monograph, this seems to be a feature in dozen+ Psathyrella or maybe even more? Field guides often ignore Psathyrella species you should consider, just take a look at P. longistriata, P. longipes, and P. candolleana. All three have lookalikes that are rarely mentioned in field guides and which microscopy would be best to distinguish from.

Now, please don’t take this as me thinking you are wrong, but more that in a genus as complicated and large as Psathyrella, I think its good to be cautious. Otherwise we are just encouraging newer less informed people to assume and we end up with a lot of people thinking stuff like Coprinellus micaceus is the only Coprinellus that looks like that and a bunch of “I’d call it that” observations to further confuse. :)

Bookmarked the Psath website.
By: Dave W (Dave W)
2012-07-16 04:59:29 PDT (-0700)

I do run across many Psaths, and with some exceptions (like the ones seen in this obs) I generally don’t get much farther than “Psathyrella” for an ID.

So now I have some new motivation to try to understand this genus.

Thanks for the info Byrain.
By: Dave W (Dave W)
2012-07-15 08:47:41 PDT (-0700)

But I do think you have miised my point.

According to all of my mushroom field guides, there are two large eastern NA Psaths that have the radial wrinkles and the membraneous veil…. P. delineata and P. rugocephala. This type is common around here. Over the years, I have examined many. Therefore, there is no reason for me to become acquainted with a broad range of micro characters spanning the genus Psathyrella, if all I wish to do is to tell one of these species from the other.

Now, if someone could tell me a specific micro character that one may use to distinguish these two species, then I’d want to spend the time/effort necessary to learn this trait.

I am a generalist amateur when it comes to understanding wild mushrooms. I approach the hobby by learing lots of different things relevant to many different mushrooms, mainly the ones I tend to find where I do most of my hunting. Also, although I do use a scope (admittedly, not a very good one) I prefer to focus on macro characters… because that’s what I see when I’m in the woods. Often — as in the case of the two Psath species — I can manage an ID with a high degree of confidence desite my not examining every last micro detail about the subject. The pages of MO contain lots and lots of high confidence proposals which are based upon macro traits only.

The mushrooms in this obs are either P. delineata or P. rugocephala.

I have arrived at my +17% rule having made hundreds of comparisons between the observed size of spores as seen using the micrometer in my scope against the reported size of the spores for the given species. I have done this with specimens where the species ID was clear without need of micro traits. For instance, Panaeolina foenisecii, which is common and often easily IDed via a combination of appearance, fragility, habitat, and spore print color usually drops plenty of nice spores that are easy to examine using my scope. So I look at the lower and upper bounds on the size of the length as seen, and adjust a percent increase to match the reported size for this species. I have been doing this for a few years.

By: Byrain
2012-07-15 00:29:51 PDT (-0700)

I’m not familiar with all the lookalikes that P. rugocephala may have, but I still think this is jumping the gun to call a species with seemingly smooth spores (Higher magnification needed to see the ornamentation?) and a iffy spore measurements (How did you determine to add 15% or 17%?) P. rugocephala. Being able to see if the pleurocystidia is present and that some are in fascicles of 2-4 should help confirm this as Lacrymaria.

If you want to better know what micro features can achieve, then please look at the Smith Psathyrella monograph freely available online, keys start at page 30. http://quod.lib.umich.edu/...
Also, you can always find good microscopes affordable microscopes online if you look around. :)

There are two fairly robust species reported for eastern NA…
By: Dave W (Dave W)
2012-07-14 14:09:30 PDT (-0700)

that have the radially wrinkled cap, and the membraneous partial veil that often partially hangs from the cap edge. Aside from spore size, I don’t know of any other basis upon which to seperate these two species. Perhaps the cystidia are different? When I bring home 6 or more fungal collections to analyze, I only bother to address the finer points when I already have a good idea about what good info may result from my effort.

Sorry, my microscope is quite limited. I’m waiting now for the college where I work to designate some scopes for reassignment (yardsale). My contact in the Bio dept assures me this is imminent. I’m hoping there’s a 1000x scope in the bunch.

As indicated within my comments, one need add about 17% to the size indicated by the micrometer in the spore photo. When I do this, I see spores that are pretty much in the L=9-10 mu range. That’s why I’m calling this obs P. rugocephala.

By: Byrain
2012-07-14 12:58:23 PDT (-0700)

What is the scale for your spore picture? Did you notice if the spores are verrucose or not? Did you look at the pleurocystidia and cheilocystidia? I would think this is jumping the gun on calling it Psathyrella rugocephala, but I am not finding any microscopically confirmed observations of P. rugocephala.

My scope’s micrometer…
By: Dave W (Dave W)
2012-07-14 07:35:16 PDT (-0700)

gives readings that are about 15% smaller than the true dimension. So these spores seem to fit the range of rugocephala.

Created: 2012-07-13 23:57:12 PDT (-0700)
Last modified: 2014-05-19 18:37:16 PDT (-0700)
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