This one was growing on a dead Polygonatum odoratum stem. There were both pale and black apos on the same stem and I think both are of the same species. The dark one's spores were slightly narrower and the oil content seemed to be a bit higher but no big difference. Both gave a vivid yellow KOH reaction.

In Gminder's key there's M. polygoni with a negative KOH reaction and M. ?polygoni with a clearly yellow reaction.

Pyrenopeziza polygoni is apparently a synonym but wouldn't the VBs and yellow reaction speak for Mollisia? That is, if this is that species. Any thoughts?

Spore measurements:
(7.6) 7.8 - 9.3 (9.7) × (2.1) 2.2 - 2.4 (2.6) µm
Q = (3.4) 3.43 - 4.2 (4.4) ; N = 15
Me = 8.7 × 2.3 µm ; Qe = 3.9

Hans-Otto Baral, 09-06-2020 18:03

Re : Mollisia polygoni?

This is a good example for the importance of vital taxonomy. What I have in my Pyrenopeziza polygoni folder are samples without VBs and therefore belong in Ploettnerulaceae.

Yours is of course a Mollisia. Now it could be that the type of M. polygoni is either a Mollisia or a Pyrenopeziza. Often those workers have made several samples and mixed both species, and a lectotype needs to be chosen to settle the identity of such an old (1842!) name.