Hydrodynamics of the Body of Dytiscus Marginalis (Dytiscidae, Coleoptera)

Abstract

The bodies of the larger Dytiscidae (Dytiscus 35 mm long Figure 1, right), Cybister 32 mm, Acilius 17 mm, Graphoderes 15 mm) are dorso-ventrally flattened. The greatest height lies just before the middle of the body, the greatest width just behind it, except that in Cybister the widest point is in the last third of the length. The sides of the prothorax and the elytra are drawn out into sharp thin ridges, which lead from the eyes along the sides until they meet caudally in a sharp semicircular edge. These ridges are highly exaggerated in Cybister and especially in Dytiscus latissimus where they form winglike margins.