Structure of the sperm of some South African archaeogastropods (Mollusca) from the superfamilies Haliotoidea,Fissurelloidea and Trochoidea

The structure of the spermatozoa of 11 species from five families of archaeogastropod (Haliotidae, Fissurellidae, Trochidae, Turbinidae, Phasianellidae) has been examined using transmission electron microscopy. All sperm are of the primitive, or ect-aquasperm type and each species has a sperm head (nucleus and acrosome) with unique morphology. Furthermore, the results from the present study together with those published in the literature reveal that, although there are a few exceptions, the size (length to breadth ratio) and spape of the nucleus and acrosome of sperm of species within each family are similar. It is therefore possible to identify members of a family and differentiate between families using sperm morphology. The intrafamilial similarities and interfamilial differences in sperm structure indicate that a spermiocladistic study of the suborder Vetigastropoda could provide interesting insights into the phylogenetic relationships of this group.