FEUERBORN HYPOTHESIS OF HYPOPYGIAL CIRCUMVERSION IN SCHIZOPHORAN DIPTERA - A REPETITION AND REAPPRAISAL OF SCHRADER (1927) STUDIES

Schrader's (1927) investigations on the hypopygial circumversion in Ca lliphora (Diptera: Calliphoridae) pupae have been repeated with improv ed techniques and more efficient control and Feuerborn's (1922) hypoth esis of hypopygial circumversion has been disproved. The development o f the male reproductive organs is described. Serious defects and ambig uities in Schrader's (1927) techniques invalidate his claims for hypop ygial circumversion in pupal Calliphora. Salzer's (1968) claims of a d ouble chiasmata in the hypopygial nervous system have been modified. T he available evidence shows that no rotation of the hypopygial segment s occurs in either the pupal or the pharate adult stages of Calliphora vicinia. It is suggested that the unique schizophoran ductus-hindgut relationship originated as a result of the coiling of the larval and a dult alimentary canals, causing an internal clockwise (seen anteriorly ) displacement of the organs concerned. The causes of the observed hyp opygial sexual differences are discussed.