Observation 281127: Otidea (Pers.) Bonord.

When: 2017-07-04

Collection location: Pikes Creek Reservoir, Pennsylvania, USA [Click for map]

Who: Dave W (Dave W)

No specimen available

On the ground in mossy area in oak woods, pine present.

Context leathery.


In cotton blue.
In cotton blue.

Proposed Names

-49% (2)
Used references: C du Q, Ascos of NA
Based on microscopic features: spore morphology fits.
Based on chemical features: Asci non-amyloid.
59% (2)
Recognized by sight
28% (1)
Based on microscopic features: I do not see the two oil droplets that I would expect to see in Otidea spores. They are usually pretty easy to see, even at low magnification.

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= Observer’s choice
= Current consensus


Add Comment
Thanks Nicolas…
By: Dave W (Dave W)
2017-08-14 02:56:20 CEST (+0200)

for the detailed response, especially for the info regarding mounting asco spores in cotton blue vs. water. Yes, it was the desire to observe ornamentation that motivated my use of cotton blue. Also, for the mention of the whitish hymenium.

My record of the context as “leathery” caused me to doubt my own Otidia proposal. But this specimen was found during a dry spell of weather, which may have had an effect.

Yes, based upon the info I have provided, we will not settle this ID. But, maybe next time…

New comments
By: Nicolas VAN VOOREN (NicoV)
2017-08-13 18:43:58 CEST (+0200)

Dear Dave,
O. onotica is very common in Europe and I never saw a collection like yours, especially with such a whitish hymenium. Of course microscopic data are always required to confirm the determination of a discomycete. As you used cotton blue for your observation, the content of ascospores has been altered. This reagent is useful to observe spore ornamentation but not the content, tap water is sufficient.
I think this is an Otidea; the yellowish color and small size support my hypothesis, but if you didn’t keep some material there is no way to control that.
Otidea oregonensis is similar but has smaller spores, 10-11.5 × 5.5-6 µm.
You may have a look to the monograph of Otidea here:

Approximate spore dimensions…
By: Dave W (Dave W)
2017-08-10 02:33:30 CEST (+0200)

are 11-13 × 6-7. (Dimensions observed from zooming the photo need to be increased by about 17% Sorry for not including this conversion info).

“Ascomycete Fungi of North America” says the spores of onotica are biguttulate. Sometimes the resolution on my scope is not fine enough to notice oil drops. But, nice big asco spores are usually not a problem. So this weighs against onotica.

Nicholas, your vote indicates your opinion is this observation can’t possibly be O. onotica. But your reason “morphology is different from typcial onotica” is no different than saying “it doesn’t look like onotica.” Could you offer something more specific? Are O. minor and/or O. phlebophora known to occur in North America? The NA Asco book mentions neither of these species names.

Might this be something other than Otidea? I’m wondering if the leathery context of this collection may weigh against Otidea.

Probably not O. onotica
By: Nicolas VAN VOOREN (NicoV)
2017-08-09 18:45:35 CEST (+0200)

The morphology is different from typical O. onotica. This looks more like O. minor or O. phlebophora.
Any data about the spore size and shape? Your micrograph of ascospores is too much small to appreciate these characters.

Created: 2017-07-07 05:30:48 CEST (+0200)
Last modified: 2017-08-14 02:56:31 CEST (+0200)
Viewed: 61 times, last viewed: 2018-08-25 15:03:46 CEST (+0200)
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