Thanks for your comment.
The asci do indeed have croziers, but the host plant here is not Ammophila arenaria.
I do not know whether Rutstroemia maritima has also been observed on other dunegrass varieties.
Do you sometimes have information about that?

R. paludosa occurs on various grasses but has a distinct stem. Here, however, all fruiting bodies are sessile or with a very short stalk.

thx for your reaction.
In any case, the substrate consists of a grass, not Carex. I will not be able to find a new collection at the moment, due to the recent frost, but I still have some material, including substrate, in collection.
In Lugol I notice no reaction, see photos.
However, I did the test with Melzer again and let the material soak a little longer. I think I see a very small reaction in the ascus top.
I also add some pictures of spores taken in water.
Sincerely,
William