First record of <i>Goniadella gracilis</i> (Verrill, 1873) (Glyceriformia, Goniadidae) in the Italian waters

Abstract The goniadid polychaete Goniadella gracilis (Verrill, 1873), currently considered as a non-indigenous species in European waters, is reported for the first time in Italian waters of the Tyrrhenian and Ionian Seas. A detailed description of individuals of this species from the Mediterranean Sea is provided, including the pigmentation pattern of the specimens, which to our knowledge has never been reported before in literature. In addition, new molecular data, 18S and COI sequences, from Mediterranean specimens are presented and compared with data from the North-Eastern Atlantic. On the basis of the available evidence, the status of G. gracilis in the Mediterranean basin is discussed, and the species is here proposed to be considered as a questionable species in the area.