Observation 100486: Amanita rhopalopus Bas
When: 2012-07-15
(35.6464° -85.3425° 518m)
No herbarium specimen

Notes: Specimen collected during Cumberland Mycological Society foray. Voucher specimen not retained. Odor of chlorine.


Copyright © 2012 Steve Roberts
Photo by Steve Roberts
Copyright © 2012 Steve Roberts
Photo by Steve Roberts
Copyright © 2012 Steve Roberts
Photo by Steve Roberts
Copyright © 2012 Steve Roberts
Photo by Steve Roberts

Proposed Names

61% (2)
Eye3 Eyes3
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
You’re also up at 1:30 am!
By: R. E. Tulloss (ret)
2012-07-17 02:16:51 EDT (-0400)


By: Steve Roberts (Mushroom World)
2012-07-17 01:30:18 EDT (-0400)

Jay felt confident this was A. rhopalopus based on macroscopic features, which is why the specimen was pitched. I’m not familiar with this species (and a ton of other Amanitas), but am learning (slowly!)

I voted “promising”
By: R. E. Tulloss (ret)
2012-07-17 00:59:52 EDT (-0400)


You guys are hard at work.
By: R. E. Tulloss (ret)
2012-07-17 00:59:08 EDT (-0400)

It is really nice to get feedback from you both about the mushroom, the methodology, etc.

Given Steve’s comments about the bulb, I think it’s pretty clear that
A. magniradix” can be eliminated in this case. The remaining issue is only that we cannot check microscopic anatomy (in this case, basidial clamps and spore size/shape).

Under the circumstances, I think we have a reasonable guess at the identity of the mushroom.

Very best to you both,


The bulb
By: Steve Roberts (Mushroom World)
2012-07-16 22:59:43 EDT (-0400)

When digging this one up, the bottom of the bulb did break off. I was able retrieve the bottom part of the bulb separately -there wasn’t too much more material, so it didn’t appear to be one of those really deep-rooting bulbs.

Also, Rod, I took your lead and abandoned the blue background photo board for gray. It’s not “photo gray,” but hopefully will be better than the blue for mushroom pics.

By: Christine Braaten (wintersbefore)
2012-07-16 22:39:47 EDT (-0400)

I have edited the observation notes to reflect that the odor had been described as that of “chlorine.” Steve has been kind enough to provide some additional photos. Unfortunately, the specimen was not kept.

You’re welcome.
By: R. E. Tulloss (ret)
2012-07-16 15:58:27 EDT (-0400)


Amanita rhopalopus
By: Christine Braaten (wintersbefore)
2012-07-16 11:52:17 EDT (-0400)

I will see if Steve or Jay will be willing to share some of their photos for this observation, thanks for the info,

About the ID possibilities…
By: R. E. Tulloss (ret)
2012-07-16 06:45:14 EDT (-0400)

Recently several MO posters been discussing ravenelii vs. rhopalopus. In this case the irregularly shaped warts away from the very center of the cap, eliminate ravenelii. So that’s a step forward.

We await news of the bulb in this material.

Very best,


Thank you, Christine. [large edit]
By: R. E. Tulloss (ret)
2012-07-16 06:36:59 EDT (-0400)

Do you know who has the specimen? [edit]

We need to know the shape of the bulb for one thing.

I’m pretty sure the “rhopalopus group” is somewhat vague — as it is used on MO.

In recent discussion with Jason Hollinger and Nathan Wilson, it was decided that the introduction of personal groupings on MO was cool as long as we could communnicate about them. This means creating and sharing some kind of definition for such things as “the Amanita X group.”

There are a number of ways this could be done. A couple that come to mind are

1. pick a group of species in which the observation’s mushroom might belong. This doesn’t have to be a grouping published by a scientist. It could just be a list of species that the poster finds confusing. The important thing is that a list puts a boundary on the poster’s problem that was reflected by creating a “group” name on MO. This draws a rather tight ring around a set of possibilities. It is scientific in the sense that it is a hypothesis that can be proved right or wrong by examination of a voucher specimen.

2. pick a set of characters that are associated with Amanita X all of which appear to belong to the species at hand, but which are insufficient to support a secure identification for the posting person.

I am sure there more possibilities, but these are two that I thought of.

As to the case at hand, if I remember correctly, there are two species in Bas’ stirps Rhopalopus in eastern North America. These are A. rhopalopus and “A. magniradix” (nom. prov.). To segregate these from pictures (all else being equal), we need to know about the bulb. The former has a bulb that is usually sausage-like and dog-legged (kicked off at an angle to one side) or, more rarely, top-shaped. The latter has an irregular root-like bulb that seems to go down forever into the substrate…I have never found the bottom of such a “radical.”

Whoever may have the specimen that backs up the images that Christine posted in this observation may be able to tell us about the bulb on it. They should be very careful to see whether the bulb seems to have been cut of or broken and what the shape of the bulb was above such a break.

Very best,


Amanita rhopalopus
By: Christine Braaten (wintersbefore)
2012-07-15 23:42:53 EDT (-0400)

I’m not so sure what “Amanita rhopalopus group” means. Would you consider this observation to be Amanita rhopalopus? I think that more information about this specimen might be available, but I do not have the material.

We need to define what the “rhopalopus group” could be. [edit]
By: R. E. Tulloss (ret)
2012-07-15 23:32:07 EDT (-0400)

To help us communicate with each other we need to know what species you would consider in this group, Christine. It doesn’t matter whether an expert thinks the species are related, what matters at the moment, it seems to me, is what taxa you would be considering when you see a mushroom like the one in your images. What is the difference to you between saying “rhopalopus” and saying “rhopalopus group.”

The species that Dr. Bas thought were anatomically close to A. rhopalopus, he placed into his “stirps Rhopalopus” which is a way of saying “rhopalopus group” with the twist that it has a scientific definition.

You can see the small number of species he included with one addition here:


You’ll see it is a small number of species and only two occur in the eastern U.S. But I am not sure if this helps you or helps you communicate about your observation.

Very best,


Created: 2012-07-15 16:08:35 EDT (-0400)
Last modified: 2012-07-17 01:10:48 EDT (-0400)
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