Observation 138348: Amanita rubescens var. alba Coker

When: 2013-06-30

Collection location: Moon Lake Park, Pennsylvania, USA [Click for map]

Who: Dave W (Dave W)

Specimen available

Grassy area with oak trees.

Proposed Names

10% (4)
Recognized by sight: Classic eastern NA Blusher.
Based on microscopic features: Spores ellipsoid
91% (2)
Based on chemical features: See comments.

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

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Thanks Rod.
By: Dave W (Dave W)
2017-06-21 04:41:27 CEST (+0200)

I had forgotten about this issue with rubescens var. alba.

The groups are segregated by a combination of nrITS and nrLSU.
By: R. E. Tulloss (ret)
2017-01-18 04:47:42 CET (+0100)

This the case despite the fact the nrITS is not simple (homogeneous) for several of the rubescent taxa. The variations are different. The segregation is possible despite the several difficulties in using nrITS and nrLSU. The project began around 2012-13.

We can segregate several of the species much of the time with macroscopic visual cues; and we are not finished working on that aspect of the work.

In the next few days, we’ll be posting more results connecting the code numbers and, eventually, an increasing number of provisional names to MO collections that helped us understand (at least to some degree) what is going on.

We are still facing at least one group only known from the genes of dried specimens with wrong names (or no names) on them. But there are distinct genetic groupings. Data on over 100 collections has been gathered. In the last few days, Dr. Hughes and I have decided to try adding Amanita flavorubens and non-North American taxa to the mix. Amanita flavorubens appears to be a highly complex group. And there are species called rubescens (incorrectly) over much of the temperate and subtropical and tropical Northern Hemisphere and sub-Saharan Africa. There are even red-bruising taxa (that haven’t been called rubescens) in Australia.

Karen is pushing forward on publications dealing with what has been learned in the the work that has been so well-supported by folks on MO.

Very best,


So, basically…
By: I. G. Safonov (IGSafonov)
2017-01-18 00:24:55 CET (+0100)

This observation and other similar observations updated by Rod today tell us that there are no reliable ways of separating whatever taxon/taxa hide behind the confusing name of A. rubescens var. alba from the entire A. amerirubescens group in the field (i.e., morphologically) unless var. alba consistently comes in pallid/white and that no species from the “amerirubescens group” can ever be pallid/white. How reliable is the working molecular hypothesis in separating these two groups based on the current choice of sequenced genes?

Nobody really understands this.
By: R. E. Tulloss (ret)
2017-01-17 20:59:10 CET (+0100)

I buy the grass roots effect as one possible cause; however, there may be other causes. If we collected white capped rubescent species in the east for which the volva was not yellow at first and for which the bottom side of the partial veil was not yellow. We’d be correct on our field ID a very large percentage of the time. But if the cap is light tan, we need some other aid for identification.

Very best,


That’s really interesting…
By: Dave W (Dave W)
2017-01-17 20:39:09 CET (+0100)

how this type mushroom with presumably pale ground color on the cap sometimes ends up with a brown cap.

Dr. Hughes sequencing shows this to fall in the rubescens var. alba
By: R. E. Tulloss (ret)
2017-01-17 20:02:02 CET (+0100)

group. Several rubescent taxa will show bruising (more or less) after the cap has penetrated the dense mat of roots of a lawn. Coker reported (and I’ve seen) purple caps on A. flavorubens in such circumstances.

Thank once more for the kind donation of material to our studies.

Very best,


Created: 2013-07-02 03:40:02 CEST (+0200)
Last modified: 2018-01-03 22:28:39 CET (+0100)
Viewed: 127 times, last viewed: 2018-01-20 09:27:29 CET (+0100)
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