Some ultrastructural characteristics of mandibular cuticle in an elaterid larva (Coleoptera)

Abstract

The cuticular walls of the mandibles of larvae of Ctenicera destructor (Brown) have a layer of nonlamellate procuticle with a preferred orientation of cuticular microfibrils and pore canals. This type of cuticle is characteristic of many pterygote adult cuticles but has not been noted in larval cuticles of other cephalic appendages or body sclerites and membranes. This nonlamellate layer is sandwiched between two layers of lamellate procuticle over most but not all of the mandibular base. There is no outer lamellate layer of procuticle in the walls of the mandibular teeth, but the layer of protein epicuticle is exceptionally thick here, comprising about two-thirds of the total wall thickness. These characteristics of the mandibular cuticle are discussed with respect to wall strength, tooth wear, function of mandibular mechanosensilla, and development.