Observation 99919: Amanita frostiana (Peck) Sacc.
When: 2012-07-09
Who: jimmiev
No herbarium specimen

Notes: Under eastern white pine, beech, oak. Spores measured from light spore drop- consistently globose to subglobose, 8.5-11 × 7.5-10 um

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Recognized by sight

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Material received some time ago.
By: R. E. Tulloss (ret)
2012-08-17 15:42:36 CST (-0600)

I opened the box today. Thank you for sending the specimen.


Thank you.
By: R. E. Tulloss (ret)
2012-07-11 00:19:21 CST (-0600)


Herbarium specimen
By: jimmiev
2012-07-10 20:12:31 CST (-0600)

Yes that is fine, I can send you the entire mushroom. I’ll e-mail you soon

By: R. E. Tulloss (ret)
2012-07-10 13:34:37 CST (-0600)

Would you be willing to send me half of the more mature specimen…or more…from the dried material? I’d very much appreciate having it in the herbarium and on WAO.

If you’d like the sporograph (which I’ve saved just in case you do), I can attach it to an email if you’ll write to me so I can get your email address.

Very best,


Thanks guys
By: jimmiev
2012-07-10 09:37:39 CST (-0600)

Rod— don’t have any iodine or Melzer’s but I do have an herbarium specimen

Dave’s questions
By: R. E. Tulloss (ret)
2012-07-10 06:32:21 CST (-0600)

I agree about thinker’s pictures in this observation. Too bad there’s no herbarium specimen…

1. Amanita frostiana has clamps at the bases of its basidia like all other taxa closely related to A. muscaria, whereas A. pantherina and related taxa apparently lack clamps throughout the fruiting body. Bas’ theory that clamp loss is not reversible is still holding up.

2. Iodine: I have never tested tincture of iodine; but, presumably, it should work to test for amyloidity. It may not produce as strong and permanent a reaction as does Melzer’s Reagent, which is said to have a more stable reaction result (unfading).

Very best,


Nice photos of some excellent specimens…
By: Dave W (Dave W)
2012-07-10 05:55:51 CST (-0600)

of a type that seems to be rather uncommon, at least in my neck of the woods.

I’m wondering about a couple things.

First, why is this species not placed within subsection Pantherinae? The mysterious, and reportedly related A. frostiana var. pallidipes is placed within Pantherinae. The types that seem most like frostiana (to me) are validipes and maybe albocreata.

Second, is a tincture of iodine which I may presumably obtain at any pharmacy sufficient test for amyloidity of spores?

Well done, Herbert.
By: R. E. Tulloss (ret)
2012-07-10 04:34:26 CST (-0600)

The spores are pretty good match for A. frostiana. This illustrates the value of having some Melzer’s reagent or tincture of iodine on hand. And check out the striate margin on the more open of the two caps.


You might also consider…[edit]
By: R. E. Tulloss (ret)
2012-07-10 03:33:11 CST (-0600)

Amanita elongata. [edit]

However, the spore measurements are too nearly globose for either flavoconia or elongata. Did you check them against the ?User+sporograph tool on WAO?

Also, the spore widths are completely out of range (high) for flavoconia, elongata, and flavorubens…all three.

Were you measuring only spores in lateral view? (Both ends in focus, apiculus in view, flattened area adjacent to apiculus in view.)

I’ll try to email you a sporograph I ran…


Created: 2012-07-09 23:00:19 CST (-0600)
Last modified: 2012-07-13 18:23:05 CST (-0600)
Viewed: 263 times, last viewed: 2016-10-26 03:10:31 CST (-0600)
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