The ‘White-clubbed’ form ofSyntomosphyrum(Hym., Eulophidae) parasitic on tsetse flies

Abstract

Cross-mating experiments are reported between adults of the typical, darkclubbed form ofSyntomosphyrum glossinaeWtstn., obtained from pupae ofGlossina pallidipesAust. from Kenya and ofG. palpalis(R.-D.) andG. morsitans submorsitansNewst. from Northern Nigeria, and the ‘white-clubbed’ form ofSyntomosphyrum, originally reported by Waterston from Nyasaland, obtained from pupae ofG. morsitansWestw. from Tanganyika.Fertilised eggs, giving rise to offspring of both sexes, were produced only by crosses between the strains of typicalS. glossinae. Crosses in either direction between the ‘white-clubbed’ form and typicalS. glossinaeresulted in all-male progeny, presumed to develop from unfertilised eggs. It is considered that this is evidence of a physiological barrier to reproduction between the two forms. The ‘white-clubbed’ form is therefore regarded as a distinct species.