#6
In the Netherlands this would certainly be D. cothurnata female. I do not know if there are similar species in Northern Europe. It is for sure not hyalipennis for the "silverstreak" on the side of the thorax should have been complete, typical for cothurnata is the fact that it is partial only near the base of the wing as is clearly visible on the second picture. Further more the light thighs are also typical.