Observation 119565: Agaricus osecanus Pilát

When: 2012-12-07

Collection location: Coleman Valley Rd., Occidental, California, USA [Click for map]

Who: Debbie Viess (amanitarita)

Specimen available

formerly more common, these big beautiful and edible Agaricus have become quite rare in the greater BA.

Collected by Hugh Livingston in coastal grassland and brought to the BAMS foray on Dec. 8, 2012.

Proposed Names

86% (1)
Eye3 Eyes3
Recognized by sight: large white cap w/skin like kidskin, very slightly yellows in KOH.
Based on microscopic features: spores elliptical, 7 × 5 microns.
Based on chemical features: odor faintly of almonds.

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

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
not merely size, although it was large…
By: Debbie Viess (amanitarita)
2012-12-10 19:51:21 PST (-0800)

not even hardly yellowing like an arvensis, not yellowing at all really, except for in KOH. that’s why I mentioned that this one WASN’T arvensis: look Ma, no yellow.

texture smooth and soft, like kid leather.

BIG but not quite as big as the Pt. Reyes crocodilinus.

NOT very fragrant but subtle, both mushroomy and a hint of almond.

Feel free to DNA this pup up if you are still in doubt. I sent the link to Fred Stevens, too.

All the features
By: Christian (Christian Schwarz)
2012-12-10 19:38:59 PST (-0800)

listed there still don’t rule out what we call A. arvensis locally. That species definitely yellows up – see description in Arora as well as photos here:
observation 93628
observation 58334, which despite being young is already yellowing

Size is not a very good feature for separating these species, unless these were absolutely huge, which it doesn’t appear they were.

It’s clear that it’s not A. bitorquis or A. bernardii

all the features listed above in the description.
By: Debbie Viess (amanitarita)
2012-12-10 19:29:08 PST (-0800)

what else would it be?

exposed to elements, but still with a smooth cap. really big. only slightly almondy and didn’t yellow to the touch, but did so ever so slightly in KOH.

too big, not yellow enuf for arvensis.

crocodilinus is also big, but in addition to its normally (but not always) warted cap, the stem is fat and squat and the spores are MUCH larger.

not briny like bernardii.

not buried like bitorquis.

first time that I have ever seen it, but I knew it was different right off. It was in a box of assorted Agaricus sp. and really stood out.

got specimen.

By: Christian (Christian Schwarz)
2012-12-10 17:52:15 PST (-0800)

The spore size here doesn’t rule out other members of section Arvenses, and I don’t see any other information suggesting it is A. osecanus.

I’m not ruling that out, I’m just wondering what made you go with that name.

Created: 2012-12-10 10:22:16 PST (-0800)
Last modified: 2012-12-10 19:39:18 PST (-0800)
Viewed: 119 times, last viewed: 2017-06-14 11:05:23 PDT (-0700)
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