The Comparative Morphology of the Dorsal Vessel and Accessory Structures of the Lepidoptera and its Phylogenetic Implications1

Abstract

The dorsal vessels of adult representatives from 34 ditrysian families of Lepidoptera were examined with the aid of vital staining. A pair of incurrent ostia was found in the mesothorax (except in the Papilionidae), metathorax, and each abdominal segment (7 in females, 8 in males). Since no excurrent openings were found in the dorsal vessel, it is suggested that the dorsal vessel may act principally as a phagocytic organ, and that accessory structures have assumed the role of haemolymph circulation. A transverse muscular septum, of unknown function, was found between the 1st and 2nd abdominal segments. Metathoraeic and abdominal cardiac variations, such as the loss of the 8th pair of abdominal ostia in females and modifications in the metathoraeic aortal pathway, are considered as secondary reflections of integumental developments. Therefore, systematic affinities and phylogenetic relationships are proposed based on mesothoracic aortal characters. The proposed phylogeny involves several modifications of previously suggested relationships based on venational and other external characters. The higher-moth relationships are in essential agreement with a 19th century work based on pupal and oval characters.