These were growing on a fallen stem of Chamaenerion angustifolium. They seem to have decent resistance to frost, since they must've frozen and melted several times. I kept the sample in the fridge for over a week and accidentally froze it again. And yet some paraphyses still had VBs. 

Asci 8-spored, IKI+(bb), without croziers. The spores measure 24.7 - 31.3 × 5.5 - 6.7 microns and are full of small oil drops.

Allophylaria macrospora seems to fit nicely, but since the species seems to be missing from our species list, I wanted to check if there are other possibilities.