Not sure that this is correct. N. gabonicus (Gahan) is a rare species with clear characters: very dense punctation on the elytral disc and a big median tubercle on the prosternal process. This is the original description: "The strong and almost quite regular transverse wrinkling in the prothorax uninterrupted by any oblique impressions on the disk, the very close punctulation of the basal part of the elytra, and the median tubercle to the prosternal process will serve to distinguish this species to any of the similarly coloured allied species.» The more commun species is N. iridescens (Atkinson) which has quite different characters. Here is the differential diagnosr by Atkinson: "This species is allied to [P.] gabonicus Gahan, of which the type remains the only specimen known to me, but can easily be distinguished by its much more brilliant and very weak puncturation, also by the absence of the strong tubercle on the prosternal process characteristic of gabonicus. » I have 2 pairs of N. gabonicus and many N. iridescens. The descriptions of Gahan and Atkinson are very correct. Also N. iridescens has shorter antennae than in N. gabonicus (see pictures)
Merci Pierre de ces précisions, autre caractéristique qu'il me semble intéressant de noter c'est la courbe supérieure du scape presque en angle chez gabonicus et en courbe régulière chez iridescens...