Corium (entomology)
The corium is the thickened, leathery, basal portion of an insect forewing or hemelytron in the order Hemiptera. Specifically the inner cell of the basal portion is the corium. Hemelytra. The forewings of the winged aquatic bugs are modified into hemelytra (singular, hemelytron), in which the basal part is thickened and leathery and the apical part is membranous. The thickened region is divided into a corium and clavus. The membranous region has veins and the venation is of taxonomic importance. However, in many families, the distinction between the leathery and membranous regions of the hemelytron is not pronounced , and the wing tends to be more fully sclerotized (e.g., Pleidae) or more fully membranous (e.g., winged Gerridae). The hind wings are fully membranous and held beneath the hemelytra when at rest. Many adult aquatic bugs are brachypterous, micropterous, or apterous, having reduced wings or none at all. However, it is common that entomologists refer to the entire basal portion of the wing as the corium.