Hallo.

Could this perhaps be something around Mycowinteria (Protothelenella) anodonta? I do not know this species but found this "semilichen" in literature as an adept in the following paper: Sherwood-Pike M. & Boise J. (1986): Studies in lignicolous ascomycetes: Xylopezia and Mycowinteria. - Brittonia, 38(1): 35-44.

Allegedly it produces occassional longitudinal septa at ascospores that should be 3-5septate. The size fits. Slightly amyloid hymenium and broad amyloid tube in ascus apex are other features according to the authors. 

Otherwise it reminds me Exarmidium that you surely know much better than me
 (called as Xylopezia by the authors mentioned above) 

Best wishes

Zdenek

Hello Zdenek,
thank you very much for your proposal and for the file. It is a good trap and I will see if I can follow it successfullly.
Best regards, Lothar
P.S. Exarmidium looks different in my opinion, but is similar in some respects, surely.

Hello Zdenek,

I think you had a false opinion of me: "that you surely know much better than me" (Exarmidium). I now think that I found E. inclusum (Xylopezia inclusa). 

Because:
1. There is not a trace of an amyloid reaction in the asci (and not in the hymenium) - with Melzer and Baral, no difference.
2. I do not find a longitudinal septum, none.
3. The spores are not so much pointed but more rounded, as I already showed before. 

So - I think Exarmidium inclusum is a good hint. I found it repeatedly in the Bavarian forest, but after the first few examinations it was only determined macroscopically from then on. 
And - it was found in fresh state, more reddish brown.

The one from Norway is black, but fully dried out, and maybe more ripe.

So I learned something again ...

Thanks again for your help!

Yours, Lothar

Hallo Lothar,

good to know that your specimen is Exarmidium in the end. I was not sure any way. E. inclusum seems to be a plurivorous species. Last year I saw it also on dried stems of the fern (Athyrium) in a herbarium specimen from Sweden.

all the best. 

Zdenek