Excellent photo, Marcello,
But you have a problem...
M. didyma is very similar to M. trivia (both occur in Italy), and both vary somewhat in therir markings.
To quote, with a Google translation (my emboldening):
"Melitaea didyma is very similar melitaea trivia with which he, north to the Southern Alps occur together in Europe, especially in the Balkan peninsula and elsewhere in southern Europe. However, the background color is usually â â even brighter orange with black markings often reduced on the upper wing surface and the â â are often heavily doused olive. The summer and autumn of moths melitaea trivia are often strikingly small and pale and usually differ from good flying in the same place representatives of M. didyma . The edge points on the hind wing underside are in melitaea trivia most pronounced triangular, with M. didyma but rather round. Both types vary greatly, depending on local climatic conditions, so there is no universally recognized distinguishing features can be specified."
However, and I have only just discovered this...
"Subspecies trivia (above, Chalkidiki, Greece, May 2004) showing discocellular vein, not present in Spotted Fritillary, M. didyma (below, Valais, Switzerland, July 2004)"
Have a look at the photos that accompany that caption
On that basis, since your specimen is lacking the vein closing (and hence creating) the discoidal cell,
your specimen is M. didyma.
But I don't know if that character is reliable, considering the emboldened sentence above.
The difficulty of separting these species obviously casts doubt on names given in the many photos of these species on the internet.
On balance, I think you are probably correct, but I can't give a firm ID.
thanks for the compliments!
Yes, I saw both the species and the most similar was the M. didyma, I had not noticed the lack of the discocellular vein!
I have done some other research and yes, seem that the M. trivia have that vein, so, if the candidates are only these two, I choice M. didyma.
But, for now I'll write Melitaea cf didyma because we aren't sure at 100%, I'll do other research and ask to an Italian Butterfly expert, then I'll back and I'll let you know the answer.
Thanks for your help and your very detailed explanations! You are helping me a lot.