Polymorphic Spermatozoa in the Hymenopterous Wasp Dahlbominus.

Studies with the light and electron microscope reveal that at least five different types of spermatozoa are produced during spermatogenesis in the arrhenotokous hymenopteran. Dahlbominus fusciupennis (Zett. Eulophidae). Two of the types differ from the others in length, one type lacks a continuous spiral helix in the head piece, and two differ from the others in the direction of the helical coil. Few of the first three types reach the female sperm-storage organ. All the spermatozoa of the last two types that do reach the storage organ have heads with either dextral or sinistral helices extending from the apex of the head to the beginning of the tail piece. The mitochondrial filaments of the tail are also spirally coiled around the central axial filament, but only in a dextral direction. It is suggested that the coiling dimorphism may be related to fertilization of the egg and may thus affect the sex ratio.