Observation 131795: Agrocybe pediades group

When: 2013-04-02

Collection location: Eldorado National Forest, California, USA [Click for map]

Who: Byrain

Specimen available

Growing around 2900 ft at the edge of a dirt road on the ridgeline under pine, the veil was rudimentary to nearly absent, maybe fibrillose.

Spore range = 15 – 19 × 10 – 12 (13) μm
Average spore = 16.1 × 11.3 μ
Q range = 1.15 – 1.73
Average Q = 1.43
Cheilocystidia abundant = 25×9, 36×9×4, 38×10×4, 39×9×4, 40×8×5, 41×8×4 μ
Pleurocystidia scattered = 35×13×5, 39×9×4, 44×10×6, 48×8×6, 48×10×6, 49×12×8, 51×12×6, 57×12×7, 58×12×6 μ
Caulocystidia abundant = 25×7×4, 30×6×3, 31×6×4, 31×6×4, 31×7×3, 32×5×7, 32×7×4, 32×8×3, 33×8×3, 34×7×3, 35×7×2, 36×7×4, 39×8×4, 44×7×3, 44×10×3, 47×8×4, 49×8×3 μ
Basidia 2-spored, clamps present

Found 4/2/13, pictures taken 4/3/13.

Species Lists


Spores, 1000x, mounted in KOH
Spores, 1000x, mounted in KOH
Spores, 1000x, mounted in KOH
Pileipellis, 400x, mounted in KOH
Copyright © 2016 Alan Rockefeller

Proposed Names

-85% (1)
Recognized by sight
Used references
Based on microscopic features
61% (2)
Recognized by sight
-57% (1)
Recognized by sight: Brown pileus, rudimentary veil
Used references: Flora Agaricina Neerlandica 6
Based on microscopic features: Large spores with a prominent germ pore of ~2 μm, pileocystidia absent, cheilocystidia up to ~40 μm long, pleurocystidia present and of a different shape/size than the cheilocystidia, spores may be a bit too big.
75% (3)
Recognized by sight
Based on chemical features: Sequence matches very well with all of the other A. pediades sequences in Genbank – including several 100% matches.
84% (1)
Used references: See phylogenetic tree here: https://mushroomobserver.org/401154?q=1WtXd A. pediades is a species complex: Malysheva et al. 2011 ITS is not sufficient to delimit species among closely related species in Agrocybe: Malysheva et al. 2019

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= Observer’s choice
= Current consensus


Add Comment
There might be Southern Hemisphere sequences
By: Alan Rockefeller (Alan Rockefeller)
2016-06-25 12:03:05 JST (+0900)

For the sequences with location information in the country field, I put that in the tree. But some sequences in GenBank have the location information in the name of the paper, or you have to read the paper to find out the location. I did that for the 100% matches, because location is most important for those – and a couple of the locations on there I had to get by reading the papers. However many of the A. pediades sequences were 99% matches, and I didn’t try to read all the papers that those sequences came from to see if I could get some additional location information. If you’d like to research the locations of the other A. pediades records that have missing locations, I can add them into the tree, or I can send you the FASTA file so you can do it.

By: Byrain
2016-06-25 10:52:26 JST (+0900)

That would be very interesting.

Another interesting idea would be to collect and sequence some Central American, South American and African specimens since those areas of the world are underrepresented in your tree. Really there does not seem to be any sequences from the Southern Hemisphere at all?

Maybe they are synonymous
By: Alan Rockefeller (Alan Rockefeller)
2016-06-25 10:45:52 JST (+0900)

Agrocybe pediades appears to be a very successful species. It would be interesting to check the microscopy on both the holotype and the Mongolian collection of A. ochracea.

Well this introduces a new problem…
By: Byrain
2016-06-25 10:23:37 JST (+0900)

How does someone tell Agrocybe ochracea from A. pediades if A. pediades sometimes has pleurocystidia?

ITS sequence and phylogenetic tree
By: Alan Rockefeller (Alan Rockefeller)
2016-06-25 10:13:21 JST (+0900)


It looks like the microscopic features of Agrocybe pediades are variable, including spore size and the presence of pleurocystidia. The Mongolian collection mentioned in the comments below is clearly a different but related species, and is in the tree. I don’t see any evidence of there being an Agrocybe pediades “group” – Everything in GenBank that is called Agrocybe pediades comes out in the same clade.

Nice paper -
By: Douglas Smith (douglas)
2013-04-15 06:48:48 JST (+0900)

Hey thats a nice paper. Interesting to see there wasn’t that much variation in Russian samples at least. Now to just add more data from California to it…

By: Byrain
2013-04-14 13:26:45 JST (+0900)

With the pleurocystidia I don’t think A. pediades is a good name for this collection which is supposed to lack it or maybe have it near the gill edge, but not differentiated from the cheilocystidia. This paper’s phylogenetic tree – http://bit.ly/Ym03mJ , includes a sister clade to A. pediades which the authors consider A. cf. ochracea with a similar spore size to my collection, but the cystidia less capitate and from Mongolia. A. pediades is a variable species so maybe A. ochracea is as well? I wonder how widely distributed it is and how many species are hiding under that name?

By: Douglas Smith (douglas)
2013-04-14 06:10:49 JST (+0900)

We have a bunch of stuff in the area that keys out as A. pediades. I think Ron had a few obs. that had some good micro-details. I don’t think there have been enough obs. to try and tell if they should get sorted into more species or not. I need to make a few better obs. of Agrocybe one of these days myself.

By: Byrain
2013-04-14 04:08:29 JST (+0900)

Thanks for the help! I also thought that the pileipellis looked like a trichoderm, but I am still not very confident with identifying pileipellis types and I will remember to look at it with H2O in the future. :)
I thought the pileipellis pointed away from Agrocybe, but perhaps not, it does seem to be a better fit. Using both keys in FAN6 I came up with A. ochracea, however the spores seem to be a better fit with A. pediades, maybe because of the many 2-spored basidia? What do you think?

Also, no pileocystidia.

With the…
By: Douglas Smith (douglas)
2013-04-14 03:20:17 JST (+0900)

The pileipellis there looks to be a trichoderm… what was the reagent used in that mount? Right KOH. Yeah, in pileipellis mounts, you shouldn’t use KOH, since it can dissolve the gelatin matrix that you might be looking for. Better to use just water, or Meltzer’s, although Meltzer’s does not help with the gelatin, it just doesn’t hurt. But with the trichoderm, this looks more like an Agrocybe. Also with the larger germ pores there, it looks more like an Agrocybe.