Drusus franzi, fifth instar larva – 2: head, thorax and anterior abdomen, lateral view; 3: head, left lateral view; arrow: toothed mandible, 4: thorax, dorsal view; arrows: anterior margin of pronotum without long setae; anterior metanotal sclerites; 5: head, thorax and abdominal segment 1, ventral view; arrow: sclerotized plate;