part_of part of part of has characteristic cuticular protrusion The region of the cuticle that corresponds to a convex surface. The surface of the cuticle in insects is the entire surface of an organism, and it is composed of flat, concave and convex regions. Convexities sometimes correspons with evaginations of the cuticle and the underlaying sinlge layer epidermis and sometimes correspond to an increased cuticular thickness." insect region of cuticle distal side convex