Observation 221401: Hymenogaster Vittad.

When: 2015-10-31

Collection location: Stump Beach Trail, Salt Point State Park, Sonoma Co., California, USA [Click for map]

38.5796° -123.332° 66m

Who: Brian Bowers (bbowers)

No specimen available

Habitat notes: In soil under coast redwood/bishop pine duff piling up against roadcut along trailside. (We were tipped off by signs of rodent foraging/digging.)

Key characters used for ID: These ones were small (1-2 cm in diameter), spherical sporocarps with pale yellow peridium and white flesh inside. Spongy, “bouncy” texture indicative of Rhizopogon.

Microscopic characters: Subspherical to elipsoid spores. (See images below.)

Species Lists


Rhizopogon spores at 400× magnification
Rhizopogon spores at 1000× magnification
Rhizopogon sp. cross sectioned

Proposed Names

-28% (3)
Recognized by sight: Tom Bruns
28% (1)
Recognized by sight: Field Guide to North American Truffles
28% (1)
Used references: Field Guide to North American Truffles

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

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Ok. Thanks for the additional photos.
By: Daniel B. Wheeler (Tuberale)
2015-11-03 11:49:47 CST (-0600)

Gleba is loculate (has chambers); also has columella (stipe-like structure). If there was a bad, chemical odor to it, it is likely a Hymenogaster. If there was a more solid structure, and had a consistency of hard cheese, if might by Hysterangium.

This may well be something new, Brian. No rhizomorphs on peridium rule out Rhizopogon; loculate ensures a host of other possibilities are present. But I personally have not seen this combination of elements before. The columella is puzzling, as I was ready to call it a Hymenogaster for sure before seeing the columella. Hysterangium usually has a columella, but is harder (has a consistency o a superball when young), and ripens to something like an overripe olive.

If Hymenogaster, then host was likely a conifer. If Hysterangium, host could be conifer or hardwood. Sorry. I’m not sure I cleared up or solved anything here.

The one thing that might help would be a comment on the odor of the observation.

Maybe those little guys are something different.
By: Brian Bowers (bbowers)
2015-11-02 22:45:46 CST (-0600)

I created another new observation post for those little guys [mushroomobserver.org/221524] and updated this observation with the largest truffle I found along the trail in the area. It was this big truffle that made me think Rhizopogon, and I just assumed the little guys were the same thing (but Daniel B. Wheeler tells me I should guess again).

Not Rhizopogon.
By: Daniel B. Wheeler (Tuberale)
2015-11-02 21:36:06 CST (-0600)

Rhizopogon does not have a pseudostipe: in this case, the pseudostipe is pointed upward.

Not sure what this is. No sectioned sporocarp provided, which would have been extremely helpful here.

Created: 2015-11-01 14:01:22 CST (-0600)
Last modified: 2015-11-03 13:01:13 CST (-0600)
Viewed: 55 times, last viewed: 2017-06-21 02:07:34 CDT (-0500)
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