Now that I look more carefully, I see that they are quite small! 22mm only is may be on the small side for a N. eminii!? The size itself would rather indicate N. peelei (Gahan), but then the pronotal ornamentation looks more like eminii.
On the basis of the specimens identified by Hintz and present at the NMHN Luxembourg, N. conradti should show rounded (and sometimes reddish) elytra. N. emini and N. bennigseni show truncated elytra. In my opinion, the species at left is a small male of N. conradti.
The specimen at right is a female, but certainly nor of conradti (which also shows eyltra shorter than body) neither of benningseni (which shows eyltra as long as body).