Helminths of the Bluntnose Sixgill Shark, Hexanchus griseus (Bonnaterre, 1788), from the Strait of Messina (Sicily, Southern Italy)

Bluntnose sixgill shark, (Bonnaterre, 1788), is a little-known elasmobranch in the Mediterranean Sea. Given the lack of information about , the aim of our study was to describe the helminth fauna of this species. In March 2023, one juvenile female specimen was found off the coast of Messina (Italy) and referred by the Italian Coast Guard to our laboratory for necropsy and parasitological evaluation. After necropsy, the specimen's gills, stomach and spiral valve were investigated for parasite presence. All collected parasites were stored in 70% ethanol for routine parasitological analysis. No lesions due to parasites were found in the gills or skin. Three species of helminths were found in one studied female specimen of , namely, two cestode species ( and sp., larvae) and one trematode ( . Among them, five Trypanorhyncha plerocercoid larvae were found attached to the stomach mucosa, and six adult cestodes and one digenean trematode were collected from the spiral valve. No other parasite taxa were found in the celomic organs. This study reports new information regarding the parasitic fauna of from the central Mediterranean Sea.