The endemic Oxychilus species of Marettimo (Aegadian Islands, Italy): O. denatale (Pfeiffer, 1856) (Pulmonata, Zonitidae)

The oxychiline zonitid Helix denatale belongs to the genus Oxychilus and is readily distinguished from all other species by its unique combination of shell and anatomy characters (shell discoidal, with many tightly coiled whorls and granulate microsculpture; long vaginal gland; very long epiphallus, very short flagellum, slender penis, extraordinarily thick penial sheath). Some of these characters are shared with other oxychiline zonitid species: a polygyrate shell with species usually assigned to Oxychilus (Hyalocornea); granulate shell microsculpture with O. oppressus (Shuttleworth, 1878), O. diductus (Westerlund, 1886) and some species of Pseudopolita; slender penis and an extraordinarily thick penial sheath with Oxychilus majori (Paulucci, 1886), but it is not yet possible to state whether they may constitute synapomorphies and support phylogenetic relationships. Consequently, discussion of relationships of O. denatale is postponed to when more data is available, at least on the other Sicilian species.