Are you sure about the location?
Was it not on the other (final) high trip, when rained almost stopped play? If so, I think we ummed and ahhed over it at the time and never saw the upperside.
Even though the white chevrons are rather uneven (
Plebejus has the white more or less evenly distributed in the pd region, while
Agrodiaetus/
Polyommatus has a concentration in ss. 3-4), I have an intuition this might be
trappi. If I'm right about the location it was certainly right next to a strong colony.
This is the typical white distribution in a
trappi male:
This is a Swiss
escheri female, showing the other extreme:
Guy