Hi Lothar,
ascomatal configuration and spore morphology are suggestive of Endoxyla or Apiorhynchotoma. If so, the spores should be apically porate and asci provided with an inamyloid apical apparatus.
Endoxyla mallochii is a possible name for your fungus, check Untereiner et al. 2013, Mycologia 105.
Cheers,
Jacques

Hello Jacques,

thank you very much for your opinion!

In the first try I did not see any asci. So - possibly this is because of the specimen being a littler bit old. I am looking forward to find the time to do another inverstigation to check if your suggestion is right. I will report then ...

Best regards from Lothar

Hi together,

I just looked to download the paper of Untereiner from

http://www.cybertruffle.org.uk/cyberliber/ - but Mycologia is there only op to issue 100.

Can somebody provide me with the paper?

Best regards from Lothar

Hi Lothar,

it can be downloaded here: https://www.researchgate.net/publication/235441594_Molecular_phylogeny_of_Boliniales_Sordariomycetes_with_an_assessment_of_the_systematics_of_Apiorhynchostoma_Endoxyla_and_Pseudovalsaria

Best wishes,
Gernot

... thank you very much, Gernot!

Best regards from Lothar

Hi Jacques,

now I have found the time to prepare two further perithecia and can answer to your questions. First: I still did not find any well-preserved asci, only few collapsed ones - the collection seems to be overmature. But there was nothing to observe with IKI. And what was very clear: the spores are distinctly porate at their dark cells. So - I think your suggestion is verified. The rest is fitting perfectly - and the substrate also. What I did not find is a hint about the yellow reaction in KOH. But maybe the authors did not test this.

Thanks again and best regards from Lothar