Thanks, everyone!!!
I wouldn't have minded to (also!) find a more usual Natrix natrix cetti, but this one was for sure a very nice individual. BTW, Frank is still on the islands until the 15th; he texted me that he found a second one in the same area. I am very anxious to see his pics.
It was very cool to see the 2 Discoglossus syntopically, to find 3 species of tortoises, to get rain when we needed it (for the beautiful Salamandra corsica), and -more in general- to find time after time exactly what we wanted to find. That's why I just love these islands. I guess the snake lovers would disagree, but the beauty of both grass snake subspecies definitely does the trick for me. I could go there each year, albeit rather without the car trouble next time...