Résumé
A new species, Labidostoma (Labidostoma) intermedia, from Iran and clearly allied to L. (L.) integrum, is described and compared with specimens of the latter from various locations. Because L. (L.) intermedia n. sp. is closely allied to the common Mediterranean species, the authors propose to consider the eponymous species group as a group gathering species which share the lateral line of pores. These species are likely vicariants in a West to East gradient from the Atlantic Ocean to Asian countries. We provide a general key setting the new species group back among the genera and sub genera previously described, as well as biogeographical and taxonomic notes.