Dear all
I would like to know your opinion about these small, rounded, blackish, more or less spherical, very small (up to 0.15 mm in diameter), most probably ostiolate but without necks, immersed in overwintered leaves of Ulmus glabra. From its characters it could perhaps fits in the genus Gnomoniella and perhaps in Gnomoniella carpinea although its spores are somewhat wider than those of this species.What do you think?
Many thanks again.

Sorry, I just saw that Gnomoniella carpinea is a synonym of Apiosporopsis carpinea, a fungus that we usually collect on carpinus leaves near the site of the find.