ULTRASTRUCTURE OF THE MATURE SPERMATOZOA OF THE LAND SNAIL EPIPHRAGMOPHORA-TUCUMANENSIS (DOERING, 1874) (GASTROPODA, HELICOIDEA)

The ultrastructure of the sperm of Epiphragmophora tucumanensis (Doeri ng), a pulmonate land snail belonging to the family Xanthonychidae, wa s examined. The results showed that this spermatozoon presents a simil ar morphology to the other advanced stylommatophoran sperm described. The most peculiar characteristic is the form of the nucleus, which is straight instead of helically coiled. An acrosome is present, composed of an apical vesicle and an acrosomal pedestal. The connecting piece or neck region is formed by a basal body plus a centriolar derivative. It is also the point of origin of coarse fibres that accompany the ax oneme. Thus, the axonemal complex exhibits a 9+9+2 pattern. The midpie ce is an elongated region composed of paracrystalline and matrix mater ials (collectively, the mitochondrial derivative) enclosing a single g lycogen helix and the axoneme. The mitochondrial derivative extends to the posterior tip of the spermatozoon. As observed in other stylommat ophorans, both an annulus and a glycogen piece are absent.