Observation 75850: Calostoma microsporum G.F. Atk.

When: 2011-09-07

Collection location: Roberts Property, Cumberland Co., Tennessee, USA [Click for map]

Who: Steve Roberts (Mushroom World)

No specimen available

This is either Calstoma microsporum, which I can find reference to its being found only once, in 1902, in Rugby, TN, which is located only 30 minutes from my property, where these specimens were found; or, Calastoma ravenelii, which has larger spores and reportedly has a smaller foot stalk than C. microsporum.

The measurements of these specimens is 4-6 cm overall length, 1.6-2 cm overall width; foot stalk 2.5-4 cm x 1-1.5 cm, spore casing 1.6 – 2 cm wide. These dimensions would fit either species, though they would be in the higher range and above for C. ravenelii.

The spore size is where it gets interesting. The spores sizes for C. ravenelii are 10-17 × 6.5-8 um. The spore size for C. microsporum (according to Atkinson, the one who worked up the original specimens) are 6-10 × 3.5-5 um. The spores for these specimens, (8.5)9 – 12(13) x 4 – 6(7) um, fit somewhere between C. ravenelii and C. microsporum. The measurements are in the upper range and above for both width and length for C. microsporum. They are in the lower range and below for length and completely below the lower range for width for C. ravenelii, with the exception of one spore (7) that was found searching for larger (and smaller) spores after the initial 10 spores had been measured at random. Note: Smith and Weber list the spore sizes for C. microsporum at (6) 7 -11 x (3.5)4.5 – 6 um, which would be a very close fit for these specimens.

I found this species once before in 2004 on my property (2nd picture), and measured the spores, and noted it was C. microsporum rather than C. ravenelii, due to the smaller spores. However, I failed to note the measurements at the time.


Calostoma microsporum (or possibly C. ravenelii)
These are the specimens I found in 2004 rather close to the location where the 2011 specimens were found. Made notes at the time “C. microsporum -taller and smaller spores than C. ravenelii,” but I didn’t record the spore measurements then.

Proposed Names

83% (3)
Eye3 Eyes3
Used references: “The Gastermycetes of the Eastern US and Canada” -Coker; 1928
“A New Species of Calostoma” -Atkinson, “Journal of Mycology,” Feb. 1903, Vol. 9, pp. 14-17
“A Field Guide to Southern Mushrooms,” Weber & Smith; 1985; p. 244
“Basidiospore Wall Ultrastructure and Tissue System Morphology in the Genus Calostoma in N. America” -Miller et al, Mycologia, 75(1), 1983, pp. 36-45, 1983
Based on microscopic features: spores white, oblong to broadly elliptical, 0-2 oil drops,
(8.5)9 – 12(13) x 4 – 6(7) um
61% (2)
Based on microscopic features: see above notes for C. microsporum

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
I see,
By: Gerhard Koller (Gerhard)
2012-01-04 09:01:03 PST (-0800)

I really thought so it would be lost effort to not keep the specimen. Someone should tell the guy from Panama the same :=)
You are still lucky, Calostoma doesn’t even exist in whole of Europe :((
I was glad to find Calostoma cinnabarinum during my US stay in North Carolina though.

not all vouchered mushroom collections…
By: Debbie Viess (amanitarita)
2012-01-04 08:42:52 PST (-0800)

are listed as such here on MO. it is easy to forget to click that box, and there are many more examples than just this one.

Indeed Gerhard, it is counter-intuitive to see the amount of work that went into this sighting and then to apparently not keep that mushroom for back-up.

Calostomas are way cool. Wish we saw them out in the West. Lucky you, Steve.

Regarding Calostoma lutescens:
By: Steve Roberts (Mushroom World)
2012-01-03 22:26:38 PST (-0800)

C. lutescens is ruled out based on spore shape -it has globose spores that are pitted like golf balls. The spores for these specimens are elliptical, and don’t have the distinctive pitting. I have found C. lutescens in the same area as these specimens.

Also, just to mention, I have found more collections of C. ravenelii AND the C. microsporm or C. ravenelii as describe here, which I will post later.

Response to Gerhard:
By: Steve Roberts (Mushroom World)
2012-01-03 22:17:10 PST (-0800)

All four species of Calostoma that appear in North America can be found in the part of East Tennessee where I live. I am preserving all specimens for my own study of this genera. When I am ready to move on, I will submit these specimens to an herbarium —likely the University of Tennessee.

Why do you guys make such exact notes on spore measurement and the like
By: Gerhard Koller (Gerhard)
2012-01-03 14:42:50 PST (-0800)

and still do not keep voucher material? I do not get this point. Herbarium stuff is very important for later checks.

Created: 2011-09-08 21:09:35 PDT (-0700)
Last modified: 2017-02-17 11:14:05 PST (-0800)
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