La diversité des Coleoptera (Insecta) du Trias dans le nord-est de la France

In the paleoentomological collection Grauvogel and Gall (deposited at EOST, Strasbourg) from the Grès à Voltzia (boundary Lower/Middle Triassic) of the northern Vosges mountains (NE France) the Coleoptera are the most diversified insects (32 species). Moreover they are very likely the most ancient true Coleoptera that are known. Unfortunately most of them are represented by strongly sclerotized isolated elytra, without any visible venation, which therefore prevent any systematic study and determination of their affinities. Indeed, the Coleoptera systematics is based upon the body features and not upon the elytra. Nevertheless, we present an inventory of the Grès à Voltzia Coleoptera based on the shape and ornamentation of the elytra in order to show the importance of their diversity. Coleoptera have been reported from other Triassic outcrops most of which are Upper Triassic in age (Kirghizistan, South Africa, United States, Australia) but in which similarly they are mostly represented by elytra. Since the elytra features have no systematic value, the comparison of the elytra from the Grès à Voltzia of the Vosges with those from the other outcrops is only superficial. The classification of most of the Triassic Coleoptera in the Archostemata, as proposed by Ponomarenko (1969) and based only on isolated elytra, is therefore very uncertain, all the more since it is not supported by any clear synapomorphy. Nevertheless, the estimated diversity of the Coleoptera from the Grès à Voltzia is interesting since it shows that at the beginning of the Triassic, they were already very diversified.