Ridged Violet Ground Beetle Carabus problematicus

Duff describes one difference between this species and Violet Ground Beetle Carabus violaceus as relating to the way the hind angles are raised above the level of the pronotal disc in problematicus but not in violaceus. I have found this confusing - even misleading. If you look at the side view photo of problematicus at ukbeetles.co.uk the hind angles drop down from the side margin to a level that is lower than the highest central part of the pronotal disc. The similar species section at the bottom of the UK Beetles website clears things up a bit with a photo comparison. If I understand correctly, it would be more accurate to say that on problematicus the rear of the side margins of the pronotum turn up to a level that is higher than the rear of the pronotal disc.

I can't blame Duff for my initial misidentification of these two, as I didn't have Duff's volume then. Apparently I did key them, but failed to note which key I was using at the time and can no longer find any key that I would have had access to then. Anyway, I identified them as violaceus, but on reviewing my records today (and with a specimen of violaceus in front of me) I realise that the elytral sculpturing is too distinct for violaceus here. Although I don't have the specimens to check anymore I am reasonably confident they must be problematicus The first photo below is one individual, the other three photos the second individual.

2x Ridged Violet Ground Beetle Carabus problematicus, Cranwich Heath (Norfolk, UK), 11th March 2017

Differentiating problematicus from nemoralis has similar problems relating to the hind angles of the pronotum. Duff again describes these as distinctly raised above the level of the pronotal disc in problematicus vs. flat or slightly deflexed in nemoralis. My misunderstanding of this difference may have led me to misidentify some problematicus as nemoralis. See my page on nemoralis for some examples that I suspect should be moved here.