Reproductive cycle of Leptaxis caldeirarum, a locally endangered Azorean land snail

The land snail Leptaxis caldeirarum (Morelet and Drouet, 1857), a hermaphrodite Hygromiidae species, endemic from São Miguel Island (Azores), is geographically limited to a range of 31 km, occupying an area of about 14 km. A preliminary study confirmed the locally endangered status of the species, raising the possibility that it could reach the “critically in danger” status, the most serious category in IUCN. A population from Ramal dos Mosteiros was studied all year round in order to elucidate its reproductive cycle and to test the validity of the total weight of the animal and the maximum diameter of the shell as diagnostic parameters for maturation. Gonadal maturation of L. caldeirarum proceeds from late winter to early summer. Intense gametogenesis takes place from January until May and the snail is apparently in a reproductive condition to copulate from late spring onwards. The strong correlation observed between the relative volumetric density of mature gametes and the maximum diameter of the shell suggests that the reproductive status of the species can be inferred from the latter parameter. This may be of major importance in future studies, minimizing potential damage to already unstable populations, and facilitating the development of conservation strategies.