When I first collected these they seemed to have a slight yellow stain on the base of the stipe and a slightly unpleasant. Unfortunately, I was recovering from a cold so my sense of smell may have been off. I thought I was getting a faint version of the typical phenolic smell and another person on the trip who is familiar with the smell confirmed it. It certainly wasn’t sweet.

The pileus first stained distinctly reddish (see third image), whereas the stipe went orangish yellow at first (see fourth image), then became more reddish and finally turned brown. However, after bringing it home, and cutting open the freshest specimen it only stained red.

The habitat was mixed pine and cedar (Calocedrus decurrens) forest in the San Bernardino mountains near the Santa Ana river. The altitude was around 5700’ (1750m). A snow plant (Sarcodes sanguinea Torrey) was blooming nearby.

Species Lists


Proposed Names

29% (1)
Recognized by sight: Definitely an Agaricus.
Used references: Nothing in Arora seems to match. Kerrigan in Agaricales of California takes me to A. spissicaulis, but based on personal communication he is no longer confident in using that European name for our California species.
86% (1)
Based on chemical features: Rick Kerrigan was kind enough to do an ITS analysis of the dried material and found that it perfectly matched the newly published species Agaricus agrinferous.

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= Observer’s choice
= Current consensus


Add Comment
By: Darvin DeShazer (darv)
2009-02-27 23:21:45 CST (-0600)

Great sequence of events!
Nice documentation to a new species.

See species page…
By: Nathan Wilson (nathan)
2009-02-26 22:46:50 CST (-0600)

I quoted both the latin diagnosis and the English version on the page for Agaricus agrinferous. A full discussion is available in Mycologia, 100(6), 2008, pp. 876–892.

Interestingly the name refers to this being a ‘lowland species’. However, this particular observation was made at about 5700’ in the San Bernardino mountains under a mix of pine and cedar.

nice! can you link to a species description somewhere?
By: Debbie Viess (amanitarita)
2009-02-26 09:12:51 CST (-0600)
By: Nathan Wilson (nathan)
2009-02-25 22:42:45 CST (-0600)

Rick Kerrigan provided the following analysis:

“Your material had an ITS DNA sequence that perfectly matched that of A. agrinferous, a species we described a few months ago that used to be known as the ‘lowland’ (or coastal) entity within A. subfloccosus.

Here’s the sequence.


More info…
By: Nathan Wilson (nathan)
2008-09-06 16:55:46 CDT (-0500)

I showed this observation to Rick Kerrigan at the 2008 MSA meeting, and he is no longer confident about using the name A. spissicaulis for non-European material. However, in personal communication he thinks this observation may well match what he reported as A. spissicaulis in 1982 & 1986. I have sent him the dried material (Jan. 2009), so we may know more soon.

Agaricus spissicaulis seems likely
By: Nathan Wilson (nathan)
2008-05-05 09:41:48 CDT (-0500)

MykoWeb mentions A. spissicaulis as occuring in California. I also just noticed the description in Agaricales. For some reason I only saw the group last night. I noticed that both Debbie’s Roger’s Mushrooms link and Index Fungorum say the name is deprecated in favor of A. littoralis (or Agaricus litoralis for the more literal minded… – looks like another r[h]ac[h]odes in the making).

By: Debbie Viess (amanitarita)
2008-05-05 09:23:40 CDT (-0500)

Not familiar with this species, but did a bit of online research. The reddening fits, general stature and veil, also the “off-smell” with age (not necessarily phenolic, but perhaps phenol is a catch-all description for "bad smells in
Agaricus?). Here’s a nice description on Rogersmushrooms