Comparative morphology of the spiracles of the Papilionidae, Sphingidae, and Saturniidae (Insecta : Lepidoptera)

The morphology, ultrastructure, and innervation of the spiracles of the ins tars and adults of representatives of three lepidopteran families were exam ined: Ornithoptera priamus poseidon and Pachliopta aristolochiae (Papilioni dae), Attacus atlas (Saturniidae), and Acherontia atropos (Sphingidae). Peritreme and atrium show stage- and family-specific structures for protect ing the internal valve apparatus. The gross morphology of the cuticular val ve mechanism is uniform within the three families, consisting of a rigid bo w and a movable bar with a lever. In adult Papilionidae, all cuticular part s (bow, bar and lever) of the valve are innervated by multipolar dendrites. Internal or external cuticular chemo- or hygroreceptors, which could parti cipate in the regulation of respiration, could not be detected in any stage . The closing muscle inserts between the tip of the lever and the base of t he bar, and is innervated only by motor neurons. The elasticity of the cuti cular system and an opener are the antagonists to the closing muscle. The s piracular opener of the adult Papilionidae and of all instars of the moths is an elastic ligament. The opener of the larval and pupal spiracles of the Papilionidae, however, is a single thickened muscle fiber surrounded by an elastic sheath of connective tissue. As it contains motor and multipolar s ensory neurons, we assume that it may function as a stretch receptor for co ntrolling the spiracular opening state. (C) 1999 Elsevier Science Ltd. All rights reserved.