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At first....Anthomyiidae =mission impossible :D, but i wil give it a try to explane why i don't think it is a P.winthemi...

I can't see on your photos if the hind tarsi is laterally expanded.
Proboscis is clear yellow, but the palpus seems dark to me
It seems also to me that the arista is long haired (but can be a movement of the arista..?)....if so, then it is not a Pegomya at all..
Also the vitta seems all orange to me, and with the one i found yesterday, its only orange on the lower part.

I only have one species to compare with, so .....i don't dare to say wich species you have on the photo.
I study hard B), but not ready yet for species level....only familie level :D:D (sometimes)

Joke van Erkelens