Observation 279066: Amanita rooseveltensis Tulloss, Kudzma, & Wasilewski nom. prov.

When: 2017-06-17

Collection location: Maple Shade, New Jersey, USA [Click for map]

39.9482° -74.9773°

Who: I. G. Safonov (IGSafonov)

Specimen available

A single mature fruiting body growing in association with the same magnificent pin oak that produced obs 207975 in late June 2015. Unlike the first collection that grew close to the trunk, this basidiocarp popped up 10-12 m away from the trunk, on the fringe of the canopy cover, and very close to the foundation of a building in an area that was recently mulched. The two collections are likely to be con-specific unless there are more than one sect. Vaginatae species associated with this tree.

The fully expanded pileus is slightly oval shaped, 6.5 × 6.8 cm in diameter, grayish-brown, with a darker disc/center and a very diffuse/shallow umbo, and is devoid of universal veil remnats. The marginal striations are 1 -1.2 cm long and comprise 29-38% of the cap radius. The gills are off-white, their edges are ornamented with the same fine pulverulent material that covers the stipe; short gills are plentiful, of variable length, and truncate.
The stipe is 10 cm long from where it merges with the cap to the bottom of the volval sack, 1 cm wide at the apex, 0.7 cm wide ~1.5 cm below the apex and 1.2 cm wide in the area enclosed by the volval sack. The stipe surface is entirely covered with a fine white powder. The stipe context has a hollow center, but the apical and basal areas of the stipe are solid.
The universal veil presents itself as a cupulate volva with 5 well-defined limbs. It is comprised of a relatively thick (up to 2.2 mm) membranous tissue and is up to 2.5 cm tall, as measured from the tip of the tallest limb down to the base of the volva. The cross-section of the volva appears to be gray.
The basidiocarp quickly produced a thick, white spore deposit. The spores appear to be broadly ellipsoid, as viewed at x400 without a mounting agent.

Microscopic Features:
[20/1/1]; spores were mounted in 10% KOH and measured in side-view only (apiculus to the side).
L x W = 9.3-10.7 (-11.4) x 7.2-9.3 μm;
L’ x W’ = 10.0 × 7.9 μm;
Q = (1.10-) 1.18-1.36 (-1.38); Q’ = 1.27; slightly inequilateral and generally ellipsoid. Only one spore was subglobose; there were 11 broadly ellipsoid spores and 8 low range (Q = 1.31-1.38) ellipsoid spores.
As it frequently happens with ellipsoid spores, the side-view orientation was not the preferred one. It took quite a while to find 20 spores in the useful disposition. Spores in face-view were observed to be wider, i.e., giving lower Q values, meaning that the cross-section of the spores is not round but oval-shaped.

June 18 Update:
After the soaking rain showers of yesterday, three more fruiting bodies popped up overnight in the same spot. They grew and matured in less than a 24 hr period! That’s impressive! Presumably it’s the same species.
Unfortunately two fbs had been “decapitated” by squirrels, as the caps were nowhere to be found. Judging by their stipe lengths (see the pic), the basidocarps were larger than the original one from the day before. The volva of the largest fb was almost 2" tall.
The third fb was growing nearby on an exposed lawn (as opposed to the mulched soil under foundation plantings) and despite its smaller size and convex cap appeared to be in decline in the hot and humid weather. The cap is more gray than brown, which is reflective of the younger age.


June 17 collection — single fb
June 17 collection — single fb
June 17 collection — single fb
June 17 collection — single fb
June 17 collection — single fb
June 17 collection — single fb
June 17 collection — single fb
June 17 collection — single fb
June 18 collection — 3 fruiting bodies
June 18 collection — the limbus internus of fb #2 (middle one)
June 18 collection — intact fb #3
June 18 collection — the cap of fb #3
Mounted in 10% KOH and viewed at x1000
Mounted in 10% KOH and viewed at x1000

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

Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
Herbarium Rooseveltensis Amanitarum (R. E. Tulloss) has received specimen.
By: mcmacher
2017-07-18 13:33:05 CDT (-0400)

We have received the dried specimen. Thank you. It is being accessioned in Rod’s herbarium.

Yup, spore contents…
By: Dave W (Dave W)
2017-06-19 18:24:42 CDT (-0400)

like broken glass, nice analogy. Same thing that I see. I’ve seen this with other types on Amanitas as well.

I know it’s cheating; my spore measurements are not recorded as rigorously as acceptable practice probably requires. I get measurement estimates by blowing up a spore photo on my computer. Not sure what sort of +- error this encourages, but when I compare my estimates for material where I already know the ID, I generally end up with measurements within the prescribed range.

Spore morphology & squirrels
By: I. G. Safonov (IGSafonov)
2017-06-19 17:21:44 CDT (-0400)

Thanks for confirming, Dave. The spores here were multi-gutulate. As a matter of fact it looked as if they were filled with greenish broken glass that reflects the light at different angles depending on how the “shards of glass” are oriented. This really helped with the measurements because I could better visualize the spore wall being contrasted against the spore contents.
Usually, small, inamyloid, hyaline and unornamented spores quickly kill my eyes — that’s why I don’t like measuring taxa from subgenus Amanita so much. Having floaters in the vitreous humor of my eyes doesn’t help either.
The squirrels used to rule around here. They are mean and provocative. It seems that their ever-increasing numbers actually embolden their behavior. Earlier this year we trapped and resettled close to a 100 of these critters, but they are already making a comeback as the woods are nearby and some folks here even feed them!

Spore morphology…
By: Dave W (Dave W)
2017-06-19 17:01:21 CDT (-0400)

matches what I have seen in the rooseveltensis collected on my lawn. I have come to the same conclusion about the spores that appear to be smaller and subglobose; it’s the profile. I’ve also noticed the squirrels like to chomp these mushrooms.

Thanks, Rod
By: I. G. Safonov (IGSafonov)
2017-06-19 16:55:32 CDT (-0400)

It’s nice to see that my data is in good agreement with those posted on your website. Here are the actual spores measurements. I noticed a couple of mistakes while originally transferring the data to MO: actually, the widest spores observed were 9.3 μm and the longest one (5%) was 11.4 μm. The average spore size and Q value remain the same though. I’ve already adjusted the numbers and other info in the microscopy section accordingly.

Spore data: 10.2 × 8.1, 9.5 × 7.4, 9.3 × 7.2, 10.7 × 7.9, 10.2 × 7.4, 9.8 × 7.4, 9.3 × 7.4, 10.5 × 7.9, 10.7 × 8.1, 9.3 × 7.2, 9.3 × 7.4, 9.3 × 7.7, 10.2 × 9.3, 10.7 × 7.9, 9.8 × 7.4, 10.5 × 7.7, 11.4 × 9.3, 9.8 × 7.9, 9.3 × 7.9, 10.2 × 8.4.

On the rooseveltensis tech tab (WAO),…
By: R. E. Tulloss (ret)
2017-06-19 15:07:02 CDT (-0400)

You’ll notice that I have previously reported a collection with average Q = 1.27.

Very best,


The squirrels like to east rooseveltensis.
By: R. E. Tulloss (ret)
2017-06-19 15:04:15 CDT (-0400)

The spore measurements are consistent with rooseveltensis. A lot of the water in the environment might over-inflate them a bit (make them a bit less ellipsoid on average).

Very best,


Spore measurements & spore pix posted
By: I. G. Safonov (IGSafonov)
2017-06-18 23:56:08 CDT (-0400)
I’ll be interested to see your spore data.
By: R. E. Tulloss (ret)
2017-06-17 23:29:32 CDT (-0400)

Very best,


Created: 2017-06-17 17:20:33 CDT (-0400)
Last modified: 2018-01-08 19:32:57 CST (-0500)
Viewed: 137 times, last viewed: 2018-01-10 02:27:05 CST (-0500)
Show Log