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I cannot be sure.
I understand the critics on nudifrons, but still my guess is it is nudifrons. I think the black on the parafrontalia just seem not to reach the antennal base but that they actually do. An artifact of the point of view of the camera. To be sure, I need a headshot from front or above.
The dark wings suggest nudifrons

Another way to determine the identity might be this:
If the picture is taken in The Netherlands outside Limburg,
it must be G. nudifrons.
Since G. rotundatum is restricted to Limburg.
G. nudifrons is actually quite common.

Maybe that helps ?

Theo