When looking more exactly I found older stromata of the Xylaria from the last year, quite strongly decayed and crumbly. On one of them I found some perithecia of a nectria-like fungus. I am not sure if it is perhaps the teleomorph belonging to the yellowish mould already showed.
The hairs of the "Nectria" are beautifully yellow and contrast well with the dark red perithecia. Unfortunately I found only few riep spores and no clear asci. The spores I measured 11-15/4-6. I am not really sure but perhaps the spores are longitudinally striate (as there were very few I am not sure if I am not talking about an optical artefact). The perithecia were mounted in KOH - and there was not decoloration, so no Nectriaceae. As the sample contains only of quite few ascomata I did not examine more perithecia by now.
Who does have an idea?
Yours, Lothar

I was a bit surprised that nobody answered to this post, as I found the specimen to be quite characteristic. Today I made new preparations and can add:
1. The perithecia show a clear discoloration to yellow (over orange) when mounted in lactic acid. As I already wrote, KOH does not lead to a discoloration.
2. This time I found a lot of spores, few also still being in (hardly visible) asci. The authentic spores are definitely longitudinally striate, and measure about 10,5-12,5/3,4-4,5 µm. 

Maybe somebody can make a proposal at least for the family, maybe the genus?
Maybe an undescribed species? - as the substrate is quite special.

Best, Lothar

Hello,
I think it's a Sarcopodium, possibly a undescribed species close to S. flocculentum. Molecular data is needed !

Andgelo

Hello Angelo,

thank you very much for your expertise! I just asked fot a publication on this species (S. flocculentum) on Researche Gate.

Do you have capactities to do the molecular work? In this case I would send you the specimen (or half of it - it is not very large). 

Otherwise, I could (not immediately, but perhaps this year) send a piece to Pablo Alvarado for commercial sequencing. I plan to do this with some fungi (mainly basidiomycetes) anyway for this year.
But I must admit: I am not familiar with the work to be done with the sequence (alignment, and so on). I would need help with this.

Somebody interested?
Yours, Lothar

... and I forgot to ask: do you think the anamorph (first contribution on top of the page) belongs to the peculiar teleomorph?

No, i'm sorry :-(

thank you for this, too!