Mysterious <i>Erepta odontina </i>(Morelet, 1851) (Gastropoda, Pulmonata, Helicarionidae)

Anatomical study of five specimens of an endemic species of the Mauritius Island, Erepta odontina showed that within one population disappearing of additional organs of the reproductive tract (epiphallic caecum, penial caecum, penial appendix, flagellum and retractor of penis) occurs in four different combinations. It is significant that the shells of all five specimens were practically identical. It is assumed that the described phenomenon has a mutagenic nature and is regarded as a rare (if not unique) case of reduction (up to complete disappearance) of additional organs within one population.