Observation 47595: Amanita sect. Vaginatae sensu Zhu L. Yang

When: 2010-06-25

Collection location: Parque de Monsanto, Lisboa, Portugal [Click for map]

Who: zaca

No specimen available

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Thanks, Dr. Tulloss, for the valuable comments.
By: zaca
2010-07-04 05:25:57 MDT (-0600)

Let me add some details about this specimen. First of all I have found it in a strange place, for an amanita: in the midle of a deteriorated road inside a natural park. In the same day I collected 3 other specimens of amanita, at a distance of about 1 meter (considered in MO# 47596). In the photo that I now upload the place is marked with a stone. Most of the tree in the zone are Quercus, although some pines also exist, and many shrubs. Relatively to the specimen itself, besides the drying in situ that you mentioned already, I have noticed some particularities of the hymenium: like the gills being sinuate and a weak colored edge of the gills.
Now some comments about the values of Q obtained. Let me say first that I’m using the french program Piximètre to obtain the data. When using this program it is not possible to obtain values for Q less than 1, because in each measurement the program takes the higest value for the lenght and the other for the widht. For instance, for this case the values obtained for Q vary from 1 and 1.45 and, moreover, 90% of them (36 out of 40)are between 1.01 and 1.25. So, as far as I can see, for the purpose of presentation of values the program calculates a normal distribuition for the data and does not takes care of its physical meaning. This is my explanation for the values that appeared in this case.
In relation to the possibilites for the species that you mentioned in your last comment, it seems to me that A. malleata is a good choice, but I have to see more details about the other possibilities.

Some possibilities…
By: R. E. Tulloss (ret)
2010-07-02 19:28:30 MDT (-0600)

I looked through my list of taxa in sect. Vaginatae sensu Yang (1997) that is organized by spore shape (Q values). I assumed that your average spore measurement might be depressed by the condition of the specimen and by the spores being rotated slightly and (thus) appearing shortened to you, the observer.

With these assumptions (which could be incorrect), the following names appeared as among the most probable determinations: biovigera (however, cap would be darker in that case), cistetorum, dryophila, and malleata. There are other names that may also come up in recent literature (some of the latter I believe are synonyms of one or another of the above four names).

Very best,


I think that this is a step toward confirming that you are dealing with a species…
By: R. E. Tulloss (ret)
2010-07-02 19:09:50 MDT (-0600)

of the group that I thought might be the most probable home to the mushroom in the present obervation.

Two things indicate to me that the spores are probably even less globose on average than you can see from your data.

1) Q values should not be less than 1.0, although I have seen this in books, I have never seen such a thing in 33 years. I think what happens is that the spore is rotated in such a manner that is not being viewed laterally. Here are some clues to when a spore is not “elligible” for accurate/proper measurement:

If a spore is symmetric in relation to a line drawn down the center of the apiculus and parallel to the two sides of the apiculus, you are most probably viewing the spore from the top or the bottom. If the apiculus is not visible, you are not seeing the spore in lateral view. If the apiculus seems to be attached at the spores apex (except in the sequestrate amanitas), the spore is not being viewed laterally. If the dimension that appears to be the “length” is shorter than the dimension that appears to be the “width”, the spores probably has its true longest dimension aligned so that it does not lie the focal plane of the lens.

2) If I am interpreting your notation correctly, about 90% of the spores measured had the same Q value of 1.1. In your case, this would imply that 36 of 40 spores have the same Q value. There is much more variation in spore shape than this in Amanita. I would expect Q distribution of mature (but not over mature) material to have a distribution corresponding to a bell-curve. In the case of a set of spores including globose spores, the normal distribution will be imperfect because it will be truncated at 1.0—-the distribution curve will have no tail extending below the value 1.0.

I wonder what happens when you allow two significant digits to the right of the decimal point in your Q value computations? Hopefully, your Q values will spread out a bit.

Additional item: an older specimen with signs of in situ drying will usually have the highpoint of the bell curve shifted to a lower number (this will be true for distribution of length or of width or of Q) when the curve is compared to a distribution curve for fresher material of the same species. The same state of the material may also cause the high value tail of the distribution curve to be truncated. This suggests that the Q you have computed or will compute after recomputation of Q values will not be as high as the Q value obtained from mature material of the same taxon found in better condition.


Here is a useful reference regarding the shrinking of spores over time; although, it addresses a single species, I have found that the observations are quite similar in other amanitas.

Tanghe, L. J. and E. Hillhouse. 1973. Dependence of spore shape on maturity of carpophore in the Phalloideae section of Amanita. McIlvainea 1(2): 1-8.


In the future, there will be a function on the new Amanitaceae website that will allow a user to enter spore data and get some analytical capability in terms of evaluating the data entered and the quality of the specimen from which the data is derived. The function is currently under development.

I’m curious to hear more about your examination of this mushroom. Good luck.


Spores measures:
By: zaca
2010-07-02 15:51:50 MDT (-0600)

4.3 [8.9 ; 10.6] 15.2 × 4.5 [8.2 ; 9.5] 13.1
Q = 0.9 [1.1 ; 1.1] 1.3 ; N = 40 ; C = 95%
Me = 9.76 × 8.83 ; Qe = 1.1
Let me add that the shorter spores are globose to subglobose and that the larger spores are more ovoide. This is not what I was expecting, but that is what I obtained.

Dear Dr. Tulloss, thank you for your detailed and constructive comments.
By: zaca
2010-06-27 17:23:58 MDT (-0600)

Unfortunately, as you mentioned, the material was in very poor condition and therefore do not have the specimen already. Still, I managed to get a spore print yet weak. I hope it is possible to obtain at least the size of the spores, which I’ll try to do as soon as possible. It seems to me, however, and in accordance with their enlightened comments, that we can now change the name for Amanita sp. (Section Vaginatae).

On the assumption that there is no bulb on the stem base…
By: R. E. Tulloss (ret)
2010-06-26 08:19:55 MDT (-0600)

Then we’re looking at either a species of section Vaginatae or section Amidella. I notice that the lamellulae (short gills) are truncate. This is true of taxa in both sections. Unfortunately, the drying of the cap in situ has caused the outer part of the cap to shrink into concentric “wrinkle” lines. Consequently, I have trouble seeing what marginal striations may have been like (if they were present).

Because the volva seems to have been weakly structured (and because the volvas of taxa in sect. Amidella tend to be multilayered and robust), I am inclined to place the mushroom in your observation in section Vaginatae.

Because the collapse and fragmentation of the volva has not left a strangulate (stretched-looking) region on the lower stipe, I think that the group of taxa similar to A. ceciliae can be eliminated.

Because the volval remnants have not become strikingly gray, I would suggest that the taxa similar to A. submembranacea, A. mortenii, A. sinicoflava, etc. is probably not the group in which the present mushroom could be placed.

Among the taxa that I know, this leaves the weak-volva’d, oval-spored taxa in the group including A. malleata and A. biovigera — a group largely (perhaps entirely) known from Europe or, possibly, taxa similar to A. populiphila.

Hence, microscopy would be necessary in order to place correctly the mushroom you’ve documented (in my opinion).

The poor condition of the material as you found it, would make it difficult to determine even if you had kept a specimen because the spores would very likely be of subnormal size and “rounder” than they would be in mature, fresh material. Also, in material that has started to dry in the field, it is common for the tissues of the gills to begin to collapse and decay; this removes critical characters that, by my current understanding, are needed to diagnose the mushroom.

Very best,


Created: 2010-06-25 16:34:09 MDT (-0600)
Last modified: 2012-06-06 15:39:21 MDT (-0600)
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