Beautiful pictures! Yes, I'd say its a H. ardens, its far too punctured on the mesonotum to be H. cupreum and while it has punctures its still shiny, which rules out H. coriaceum.
The top one is a H. ardens, as H. coriaceum is much more matte on the mesonotum from the very rough punctation. The others looks like H. ardens too, but I'm not sure from the pictures, cant really see due to the blur.
I'm not sure if they are one and the same species. Hedychridium ardens gezien op 2015-06-14 Tilburg - Huis ter Heide - Vosberg The ... and day: http://waarneming.nl/waarneming/view/103513405 Hedychridiumcoriaceum ? gezien op 2015-06-14 Tilburg - Huis ter Heide - Vosberg The Netherlands ...
... [RUS, nn.] = soul) [f.] Hedychreides (derivated from Hedychrum ) [m.] Hedychridium (derivated from Hedychrum ). Comment: we are sure that Abeille ... is referred to the "spaced" punctuation on the abdomen. [i] coriaceum (from coriaceus, a, um [LAT, adj.] = leathery). Comment: the name ...
... H. jucundum , a species with somewhat similar coloration, is different, among other things, in both of these aspects. H. krajniki is more like H. coriaceum with respect to punctuation, as far as I remember.)
... have other species in Czech Republic which it can be confused with however. From the cropped picture it is obvious that it is not H. cupreum or H. coriaceum, which (at least in Sweden) are the two other species it can be confused with. /Alex
... Al momento della cattura l'avevo smistata in una provetta con degli Hedychridium krajniki Balthasar, 1946 ma ad una osservazione più accurata ... :( Simile al Hedychridium krajniki ci dovrebbe essere il Hedychridiumcoriaceum (Dahlbom, 1854); che sia lui? ...però il torace non è così coriaceo ...