A medium sized Peziza, identified as P. arvernensis, but when examining a recent collection I noted some differences which may or may not be important. The specimens (2 collections, different years) were collected one on decomposing branches (Quercus ilex?) and one on soil (buried wood?). The flesh is 2mm thick, under a hand lens 3 layers can be seen - the dark subhymenium, a clear centre and a dark ectal excipulum. Under a microscope 5 layers can be made out, excluding asci & paraphyses.
The subhymenium (layer 5 in Donadini) consists of a narrow layer composed of a mix of textura intricata with elements of t. globosa-angularis. Medullary excipulum is made up of 3 distinct layers. The upper layer (layer 4) is wide (600µm) and made up of textura globosa with some cells reaching 175µm in diameter. The middle med. excipulum (layer 3) consists of a narrow layer (220µm) of t. intricata with some globular elements reaching 50µm diameter. The lower med. excipulum (layer 2) consists of a wider (250µm) layer of t. angularis (some elements up to 70µm wide). The ectal excipulum (layer 1) is a dark coloured layer (360µm thick) composed of t. intricata.
Asci 280 x 13µm, pleurorhynchus base. Paraphyses slightly inflated at the tips (6 - 9µm), septate, hyaline. Ascospores Mean 17.2 x 10.2µm; Qe = 1.69, ellipsoid, hyaline, eguttulate, rough (but no specific ornamentation seen with CB not with oil immersion unfortunately; when examining images, at high contrast, one can see a central oil drop which is not visible normally - perhaps an artifact of my setup.

The species appears somewhere between arvernensis and pseudosylvestris (particularly the wide upper med.excipulum) but P. pseudosylvestris is not a European species. Donadini separates the 2 species by the very wide 2 & 4 layers which this collection appears to have, but the spores do not show particular ornamentation. Has anyone collected P.arvernensis which such wide layers?