I hope someone can help me with this one.

Ecology: On oak cupule

Macroscopic description:

Perithecia slightly pyriform, about 0.35 mm in diameter and 0.4 mm in height, with a brown-orange colour (no colour change in KOH). Seated superficial on the cupule surface without an obvious subiculum. The ostiole is distinctly cone-shaped and slightly darker in colour than the surrounding perithecial wall.

Microscopic description:

Perithecial wall consists of round to angular, somewhat thickwalled brown cells of usually 20-30 µm of diameter. At the perithecium base I observed very thickwalled hairlike Elements > 100 µm long and about 10 µm  in diameter (see photo).  Asci extremely thinwalled, nearly invisibly surrounding spores, spore-bearing part about 70 x 20 µm, no iodine reactions. Spores 50-55 x 5-6 µm, yellowish, 3-septate and often bent, with many oildrops.

Thanks for any help

Stefan

Alain GARDIENNET, 26-11-2013 08:55

Re : Perithecia on quercus cupules

It's a Calonectria species.
You should re-name the title of your message with the word "Calonectria" in order to be attractive for the specialists oh this genus.
Alain

Jacques Fournier, 26-11-2013 09:08

Re : Calonectria on quercus cupules

Hi Stefan and Alain,
Alain is right, it is a Calonectria, most likely C. pyrochroa which can occur on various substrates but is often present at this season on dead acorn cupules of Quercus in the litter. The greenish refractive hairs are those of the host, I had fallen into the trap too!
Cheers,
Jacques