Occurrence of Dipturus nidarosiensis (Storm, 1881) in southern Adriatic and Ionian sea

Geographical distribution of Norwegian skate Dipturus nidarosiensis is known to occur along the Atlantic coasts, from Iceland, Faroe and northern Norway to Madeira and northern Marocco. Recently however this species was recorded in western Mediterranean sea, along southern Sardinia coasts . In this study we report for the first time the records of the catch of 6 specimens in Southern Adriatic and Ionian Sea, providing morphological (total length; total weight; length at first dorsal fin; disc length and width) and biological (sex and maturity) measures. These specimens were collected during several biological samplings (DCF landing and discard surveys, MEDITS trawl survey) from 2008 to 2011. The classification obtained from morphological characteristic has been confirmed by molecular analysis, sequencing a 601 bp fragment of the mitochondrial cytochrome oxidase 1 gene. The depth of capture ranged from 600 to 1144m with a total length and weight included respectively from 70.5 to 123.5 cm and from 1137 to 10043 g. Only one specimen was female, the other 5 were males. The occurrence among the few caught individuals of different stages (adults, matures, juveniles) and of both sexes would suggest the presence of a local population that lives in deep waters (slope and bathyal bottoms) only partially visited or completely unexplored by commercial vessels. Moreover, the presence of this species in the central and eastern Mediterranean Sea would corroborate the hypothesis of the ancient occurrence of the Norwegian skate in the Mediterranean Sea, but unnoticed or misclassified with others species of Dipturus.