Observation 55924: Acervus epispartius (Berk. & Broome) Pfister

When: 2010-09-08

Collection location: Boston, Massachusetts, USA [Click for map]

Who: Jason Karakehian (Jason Karakehian)

Specimen available

I found this in wood chips in my back yard in Allston and was stumped. I took it to Don Pfister at the Farlow Herbarium and he ID’d it as Acervus epispartius. Apparently, this may be the only collection of this fungus in Massachusetts!
It was a real stumper! I had trouble because I just couldn’t figure out if it was operculate or not because I did see one true operculum but didn’t see it anywhere else in the hour or so I spent looking at this thing. What I was seeing didn’t match anything in Seaver, Fungi of Switzerland, Dennis, etc… but it is in Bessette.
The apothecia are about 2cm at the largest, bright orange with a felty, whitish underside. Astipitate. Young ascocarps have a flap that covers the hymenium, and as the body opens, the flap ruptures but clings on for a little while before falling off. If you look hard you can see the little flap still clinging on to the margin of the mature fruiting body. That’s a good macro-characteristic for this fungus.
Also, under Don’s and Kathy LoBuglio’s supervision at the Farlow, we tried to culture the spores and tissue with no success. Don tried a heat and cold shock treatment on some plates but no luck.

Species Lists


This picture shows the apothecia but none of those distinctive flaps. I didn’t take any other pictures! Drat!

Proposed Names

80% (1)
Used references: Occasional Papers of the Farlow Herbarium No 8 May 1975 by Don Pfister
Mushrooms of Northeastern North America, Alan Bessette et al. pp 487-489, illus. p. 498
Based on microscopic features: Spores smooth, cylindrical with blunt ends (they look just like tylenol capsules!), hyaline. 7.6 × 4 microns, one guttule.
It’s difficult to tell if this is operculate or not, and reading the materials, apparently I’m not the only one who had trouble. Operculi are few and hard to see, and the asci mostly dehisce by means of a tear or rupture. No iodine reaction at all. Contents of paraphyses yellow.

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= Observer’s choice
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Created: 2010-10-19 04:40:52 PDT (-0700)
Last modified: 2010-10-19 04:47:30 PDT (-0700)
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