Observation 215566: Agrocybe pediades group


sandy tallgrass prairie restoration
growing singly, found a few times
thin stem (a few mm across)
cap about 1cm across
no veil/ annulus present (viewed under dissecting microscope)
brown spores and gills
two fruiting bodies collected, both already old and dry
KOH reaction: distinct darker brown (nearly black) colour change vs. dH2O control of only slightly darker brown than dried cap surface

My original microscopy notes:
spores ovoid-oval-elliptical, with germ pore, smooth
gill trama parallel
Greg Thorn additional microscopy 2017-01-20:
Spores: 11.2-13.6 × 7.6-9.2um, germ pore 1.5-2um wide
cap cuticle filamentous (? I’m not confident in my ability to tell, section/setup micro properly) *Greg says the specimens are too old and dry for anyone to assess this feature properly

Psilocybe, Stropharia, and Tubaria have filamentous cuticle
Agrocybe, Psathyrella, and Panaeolus would’ve been my guess, but cuticle should be cellular then
Need to look into this more, and other features

I mistook earlier for another Psathyrella ammophila (also present in this prairie)

Sequencing notes:
Prelim partial sequences match to Agrocybe in GenBank blast uery…
Final sequence of partial SSU through to partial LSU (including ITS in middle) returns Agrocybe smithii as top hits and other unrelated LBMs, not Agrocybe pediades sequences of the same regions that are also available in the database… could be multiple reasons why, not further investigated

Species Lists


dissecting microscope on dried specimen
in situ
dissection gills closeup
dried cap surface
parallel gill trama (gill c.s., phase contrast)
brown ovoid-oval-elliptical spores
phase contrast spores, you can see there’s that pore opening part where they broke off their sterigmata… germ pores! no ornamentations
cap cuticle seems filamentous (from an “oblique”? section of cap)
filamentous cap cuticle (ignore the blurry under-layer and you can see the texture clearly)

Proposed Names

28% (1)
Recognized by sight
-18% (3)
Based on microscopic features: Spores with a germ pore. Pileipellis type excludes Conocybe and Agrocybe.
-46% (2)
Used references: better specimens later found on site that were sequenced…
46% (2)
Used references: Partial sequence for 28S(LSU) of 611bp matches strongly with Agrocybe spp… 99% coverage and 99% identity for Agrocybe praecox, pediades, and smithii
e.g. Accession KC176295 A. smithii T-792 from Thorn et al 2012
Based on microscopic features: spore colour, shape, presence of germ pore
61% (2)
Recognized by sight: no partial veil, thinner stem than other spp., grassland growth
Used references: Flora Agaricina Neerlandica 6 (Noordelos, Kuyper, Vellinga 2005)
Kuo, M. (2006, September). The genus Agrocybe. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/agrocybe.html
Based on microscopic features: spore size fits
Based on chemical features: KOH reaction on cap (described by Kuo)
28% (1)
Recognized by sight
28% (1)
Used references: Flora Agaricina Neerlandica 6 (Noordeloos, Kuyper, Vellinga 2005)
Based on microscopic features: Greg Thorn says the cystidia shapes fit reasonably well, comparing between A. pediades and A. ochracea in Flora Neerlandica (pg 213/4)

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= Observer’s choice
= Current consensus


Add Comment
This sequence is included in a phylogenetic tree here:
By: Terri Clements/Donna Fulton (pinonbistro)
2020-11-09 00:29:41 IST (+0530)

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

Interesting sequence result
By: Alan Rockefeller (Alan Rockefeller)
2017-12-31 19:53:01 IST (+0530)

The Agrocybe pediades I have sequenced matched A. pediades sequences from all around the world. Are you able to share the sequence data?