Early embryonic development of the primitive moths, Endoclyta signifer walker and E. excrescens butler (Lepidoptera : Hepialidae)

Abstract

Little information is available on the embryology of primitive moths. This paper describes and discusses the early embryogenesis of the monotrysian moths, Endoclyta signifer and E. excrescens. The small round germ disk is formed in the posterior ventral part of the egg. It invaginates into the yolk, and becomes the sac-like germ rudiment. Soon after, it separates from the rudimentary serosa, and completely sinks into the yolk. This sac-like germ rudiment develops into the germ band. In both species the embryonic envelopes are formed from the amniotic folds. The formation of the germ rudiment and embryonic envelopes in Endoclyta resembles those of Neomicropteryx nipponensis in the Zeugloptera and Stenopsyche griseipennis in the annulipalpian Trichoptera, and differs from those of the ditrysian Lepidoptera. The close affinity between the primitive Lepidoptera and the Trichoptera is supported by the present embryological evidences.