Delayed spermatophore removal in the land snail Euhadra peliomphala

Although many studies have demonstrated that variation in male genital morphology can influence male fertilization success, it remains unclear in many cases which mechanism(s) of sexual selection and sexual conflict produce the morphological divergence of genitalia. Distinguishing between such mechanisms requires, at the very least, information on the process by which genital morphology influences fertilization success. The length of the spermatophore-producing organ (SPO) of the stylommatophoran land snails is a case in point. The length of the spermatophore may have an important influence on the transfer of the spermatophore to the recipient's genital tract. To test this hypothesis, we investigated in Euhadra peliomphala (Pfeiffer, 1850) the relationship between the length of the SPO in sperm donors and the position of their spermatophore in sperm recipients at 72, 84, and 96h after mating. The results showed that longer spermatophores required longer times to reach a gametolytic organ and to begin to be digested. These findings suggest that this delay in spermatophore digestion explains the mechanism for the high fertilization success shown by snails with a long SPO.