Hi Andreas, welcome to the forum.
For a first post, you strike hard!
I came across a similar fungus, also on the banks of a stream, on Robinia wood, which just differs from yours by thick slit-like ostioles and slightly smaller ascopores 18.5-22.5 x 8.5-10 µm with curved germ slits in each cell (photo attached), a gelatinous sheath and not breaking apart.
All I can say about it is that it is a Dothideomycete with bitunicate asci and ascospore morphology suggests affinities with Delitschia. I suppose it might be an undescribed genus because such a turquoise green stain of the substrate is much uncommon. Unfortunately the collection could not been cultured nor sequenced.
I wish you to go further than me!
Best,
Jacques

Hello Jacques,

thank you very much for your interesting comment!


Best regards from Austria,

Andreas