Bonjour tous
this fungus appeared on incubated fallen leaves of Quercus ilex, collected beneath a mature tree in Scarborough on the North Yorkshire coast (where the tree is of course non-native).
Non-stromatic, with a medium-length, centrally-positioned neck, occurring over the lower surfaces of the leaves, most obvious where appearing on the main vein. The main distinctive feature is the long, narrowly falcate ascospores -
22.3-26.7 x (2)2.2-2.6µm, fasciculate in the asci, and with an often difficult-to-observe central septum.
Reference to Barr (Mycol Mem. 7) produces only one species on Quercus with ascospore dimensions comparable with the current species - Pleuroceras lirellaeformis - but that genus has lateral beaks and the ascospores of that species are described as "broadest above, tapering to pointed base", whereas this fungus has symmetrically falcate spores.

any suggestions would be very welcome
amitiés
Chris