I found this Peziza just inside a fallen, dead, hollowed out Poplar tree.  It was fruiting on the pulped wood inside the hollow. The spores vary in length from 12-15µm (-17µm) x 8 -8.5 (8.7). They are very faintly punctate and aguttulate. My first choice would have been P. micropus due to the simple paraphyses, however, having taken a section of the flesh, not only did I observe layers in the flesh but under the microscope I noticed chain-like cells similar to those associated with P. varia, but the chained cells did not have long, projecting end cells, hence my quandry. Please find a series of pictures, of the ascomata in situ, cut in section and microscopic shots of spores, paraphyses and the chained cells. Any help toward clarification most appreciated.
Thanks in advance Andy