I'm having trouble identifying a pyrenomycete I collected last week in New York City. I believe that the substrate is Rhus typhina, which was lying on the forest floor of a Bronx park.

The reddish stromata are erumpent through the bark of the substrate. The surface is quite wrinkled and quite deeply sulcate around the ostioles. The ostioles are black and most ejected a large blob of dark spores. The interior tissue is black. Perithecia are embedded at many different depths in the stroma with long necks. The tissue produces red pigments in KOH.

Asci are 123-134 x 11.8-12.5µm. They appear to be bitunicate, or if not, quite thick-walled. IKI-

Spores brown, 1-septate, constricted at the septa. For the most part, the two cells of the spores are equal in size. There appears to be a texture to the spores. Perhaps they are punctate, or maybe they are pitted? 15.5-19.9 x 6.9-9µm. Q= 2.2 N=20

Paraphyses (Pseudoparaphyses?) about 2.5µm wide.

Does anyone recognize this pyreno?

Thanks in advance.

Ethan

Jacques Fournier, 19-11-2021 22:17

Re : Red stromatic pyrenomycete

Hi Ethan,

Nice fungus. Myrmaecium rubricosum (Fr.: Fr.) Fuckel, formerly a Valsaria.

Cheers,

Jacques

Jacques Fournier, 20-11-2021 15:24

Re : Red stromatic pyrenomycete

you are right, distinguishing both species may be indeed challenging when dealing with aged stromata with dull colours.

The overall yellow tone of stromata of M. fulvopruinatum is usually diagnostic compared with the orange brown tone of M. rubricosum. The reaction to KOH you show is more red than purple, which might fit fulvopruinatum better.

Asci (not ascospores) of M. fulvopruinatum are termed unstable because they frequently dehisce in water, unlike those of M.rubricosum. Ascospores are usually too variable to be reliably diagnostic.

I leave you check the other details until you make your mind and give it a species name.

Good luck!

Jacques

Hermann Voglmayr, 21-11-2021 09:58

Re : Red stromatic pyrenomycete

Dear Ethan,
I agree with Jacques that aged Stromata of fulvopruinatum lose the yellow scurf and then mimick rubricosum. According to own observations fulvopruinatum is much more common at least in Europe , and this may be also the case in other temperate areas.
Concerning your collection I assume it is fulvopruinatum as the two small stromata clearly have a yellowish hue,  a feature I haven't seen in rubricosum.
Best wishes Hermann

Jacques Fournier, 21-11-2021 14:29

Re : Red stromatic pyrenomycete

Dear Hermann and Ethan,

you are obviously both right about fulvopruinatum. I missed this photo showing the yellow scurf.

Ethan, you just need now to find rubricosum for comparison????

Jacques