The Nervous System of Certain Abdominal Segments and the Innervation of the Male Reproductive System and Genitalia of Hyalophora cecropia (Lepidoptera: Saturniidae)1

Abstract

The musculature and its innervations in the fourth pregenital abdominal segment of the adult male cecropia moth are described. Dorsal, ventral, and transverse pairs of nerve roots arising from the pregenital segmental abdominal ganglion seem homologous with those described for the pregenital segments of certain Orthoptera, the neuropteran Chauliodes formosanus , and the cecropia larva. In this lepidopteran, as in those other orders, the dorsal nerve fuses with the transverse nerve of the preceding ganglion, and the spiracular muscles are innervated from the fused branches of the dorsal and transverse nerves. The ventral nerve in this species and in some Orthoptera fuses with the transverse nerve of its own segmental ganglion. The homologies in such widely separated insect orders support the concept of a basic segmental nerve pattern within the Hexapoda. The terminal abdominal ganglion lies in the sixth abdominal segment in the cecropia male and gives rise to the lateral nerves of the sixth, seventh, and eighth abdominal segments, as well as the trunk giving rise to the branch nerves that innervate the reproductive system and the genital musculature. The vasa deferentia loop beneath the lateral nerves innervating the rectum, anal tube, and body wall in the anal area. If these relationships are homologous with the position of the lateral nerves of the 11th abdominal segment in Orthoptera, the nerves passingabove the vasa deferentia in this moth are the lateral nerves of the 11th abdominal segment, which is no longer recognizable as a segment in Hyalophora cecropia (L.).