Metacestodes of Elasmobranch Tapeworms in (Mollusca, Cephalopoda) from Central Mediterranean-SEM and Molecular Data.

Cephalopods are intermediate/paratenic hosts in the life cycle of elasmobranch tapeworms, nevertheless most records of infection in this group of mollusks are outdated and fragmentary. The present work aimed to investigate the cestode fauna of the common octopus from the Tyrrhenian Sea (Central Mediterranean). The parasitic stages were characterized by light and Scanning Electron Microscopy (SEM) and sequencing of 28S rDNA. Three cestode taxa were identified to the genus level: the onchoproteocephalidean sp. (prevalence 28%), the "tetraphyllidean" sp. (prevalence 13%) and the trypanorhynch sp. (prevalence 3%). The remarkable prevalence observed for gastrointestinal cestodes highlight a possible important role of in the transmission of elasmobranch tapeworms, particularly Onchoproteocephalideans. Furthermore, the present work provides, for the first time, detailed morphological (SEM) and molecular support to confirm the occurrence of sp. in cephalopod hosts. In order to gain higher taxonomic resolution for the identified taxa, we stress the need to collect further morphological and molecular data of adult cestodes infecting their elasmobranch definitive hosts.