המועדפים של abieri

Calopteron terminale because (1) transverse depression on elytra, (2) uniformity of ridge heights, and (3) blue tinge. I'm not sure how useful blue tinge characteristic is (from BugGuide page on species). In case useful for anyone else learning about this genus I took a stab at some visual ID tips (on pic #2):



The other two members of the genus in the United States and Canada are Calopteron reticulatum and Calopteron discrepans. I have a blog post with more pics.

Please also see the very similar Caenia dimidiata.

There are many more species (100+?) in Mexico, Central America, and South America but those species are not yet logged into iNaturalist. So if you have observed a Calopteron outside of the United States, keep your ID at the genus level even if it sort of looks like one of the three species in the United States.