Variation in spermathecal morphology and storage of spermatozoa in the simultaneously hermaphroditic land snailArianta arbustorum(Gastropoda: Pulmonata: Stylommatophora)

Abstract

Morphological investigations showed that the sperm storage organ (spermatheca) of the simultaneously hermaphroditic land snail Arianta arbustorum consists of 2–8 tubules with a common entrance. Sites of sperm storage were examined in snails that mated once (eight individuals) or twice (ten individuals). After one year during which the snails laid eggs only one individual of those which copulated once had some spermatozoa in one spermathecal tubulus. In four snails of those specimens which copulated a second time after one year, a part of the tubules was filled with spermatozoa while in the remaining six animals no spermatozoa were found in the spermatheca, although they received a spermatophore 5 days before fixation. In these latter snails spermatozoa were found exclusively in the sperm-digesting bursa copulatrix. This suggests that the female reproductive system of A. arbustorum may possibly be able to control fertilization by a selective storage of spermatozoa from different mating partners.