Moreletina, a new genus of hygromiidae (Pulmonata : Stylommatophora) from Santa Maria, Acores

摘要

Moreletina, gen. n. is proposed for Helix obruta Morelet, 1860, endemic to Santa Maria, Acores, and previously believed to occur only as a fossil. Characterized by possessing a single biramous mucous gland and a vestigial dart sac, a penial appendix, and a double-walled penial papilla, the new genus is related to the Madeiran hygromiid Geomitrinae, with which it shares a common continental European ancestor. The anatomy of Moreletina obruta is described in detail. The species shows two ecophenotypes: a light form, described by Morelet, living among grass on calcareous substrates, on the southern coast of the island, and a dark form, associated with the dark basaltic rock, living on the northern coast of Santa Maria. Besides body coloration, these two ecophenotypes differ in shell size, but do not show any detectable anatomical difference.