Endemic freshwater planarians of Sardinia: redescription of Dugesia hepta (Platyhelminthes, Tricladida) with a comparison of the Mediterranean species of the genus

The endemic freshwater planarian Dugesia hepta from Sardinia was described mainly by karyology
and karyotype analysis and by geographic distribution. The present paper reports on the detailed
morphological study of the copulatory apparatus and highlights the fact that the exclusive diagnostic
characters of D. hepta are the shape of the penis papilla, the course and opening of the ejaculatory
duct and the openings of the shell glands. A neotype is designated on the basis of a detailed
description, and the geographic range of the species is better defined. The two phylogenetically
important traits represented by the course and opening of the ejaculatory duct show an unknown
condition in the genus Dugesia, diverging from the typical one displayed by the other 69 species. A
comparative analysis of morphological traits of the 20 Mediterranean species of the genus Dugesia was
made.