A systematic revision of the vitrinid semislugs of the Azores (Gastropoda:Pulmonata)

Abstract

A total of six species, all endemic, are recognised in a comprehensive taxonomic revision of the vitrinid semi-slugs of the Azores. All are referred to the genus Plutonia on the basis of the disposition of the penial retractor muscle. One species, P. brevispira, is highly unusual in lacking a vaginal stimulator and having a large, elaborate penis which would appear to function as an intromittant organ during copulation.