You are probably correct - Peribatodes rhomboidaria.
P. secundaria is very similar; but some differences in markings on the wings differentiate them - see 'Similar Species' in this page - http://www.lepiforum.de/lepiwiki.pl?Peribatodes_Rhomboidaria.
P. perversaria is also similar, but actually different to yours; see http://www.lepiforum.de/lepiwiki.pl?Peribatodes_Perversaria.
I do not have distribution maps for these species, so cannot use distribution to confirm or deny any of those three species occur in your area.
Hi there, I don't want to put the cat among the pigeons but is it possible that the moth shown might be the Mottled Beauty, Alcis repandata? I base this supposition on the dark streak at the beginning of the median facia on the costa. Just a thought, I may be wrong.
First: welcome to NaturePlus. Nice to see another mothman here. Always good to have an extra mind on the task. I see you're catching up on some of the older discussions.
I get the dark streak aspect (present in the specimen for ID and in P. rhomboidaria). However, IMO, A. repandata usually has, in the forms without the broad dark band, a darkish splodge in the middle-outer part of the forewing; lacking in the specimen for ID.
The other Italian species of A. have distinguishing marks that don't match: