New records of non-indigenous species from the eastern Mediterranean Sea (Crustacea, Mollusca), with a revision of genus Isognomon (Mollusca: Bivalvia)

We report new data on non-indigenous invertebrates from the Mediterranean Sea (four ostracods and 20 molluscs), including five new records for the basin: the ostracods , aff. , cf. , cf. (Arthropoda: Crustacea)-the first records of non-indigenous ostracods in the Mediterranean-and the bivalve aff. (Mollusca). Additionally, we report for the first time from Israel, and , , , , , , aff. and from Cyprus. We also report the second record of sp. and of sp. cf. in the Mediterranean Sea, the first live collected specimens of from Cyprus and the northernmost record of in Israel (and the Mediterranean). Moreover, we report the earliest records of , and in the Mediterranean Sea, backdating their first occurrence in the basin by 3, 5 and 7 years, respectively. We provide new data on the presence of and aff. in Israel. Finally, yet importantly, we use both morphological and molecular approaches to revise the systematics of the non-indigenous genus in the Mediterranean Sea, showing that two species currently co-occur in the basin: the Caribbean , distributed in the central and eastern Mediterranean, and the Indo-Pacific . aff. , at present reported only from the eastern Mediterranean and whose identity requires a more in-depth taxonomic study. Our work shows the need of taxonomic expertise and investigation, the necessity to avoid the unfounded sense of confidence given by names in closed nomenclature when the NIS belong to taxa that have not enjoyed ample taxonomic work, and the necessity to continue collecting samples-rather than relying on visual censuses and bio-blitzes-to enable accurate detection of non-indigenous species.