Isopoda (Crustacea) from the Levantine Sea with comments on the biogeography of Mediterranean isopods

Abstract

This study focuses on the isopod fauna of the eastern Mediterranean, mainly from the waters of Lebanon. Ninety-five samples containing isopods were obtained by scuba diving (depths from 0 to 44 m) at 32 stations along the coast of Northern Cyprus, Syria, and Lebanon. The most frequently sampled substrates were caves, vertical walls, and calcareous algae crusts or build-ups. A total of 502 individuals were studied, belonging to 28 species and included in 20 genera, nine families, and three suborders. Four new species from this collection (Atarbolana beirutensis, Cirolana bitari, Cirolana zibrowiusi, and Mesanthura pacoi) have already been published. Brief diagnoses and illustrations were included. The collection studied here consists mostly of Mediterranean species, some already known in the area. Ten (eleven, when the cf. species is confirmed) are new records in the Levantine Sea (Apanthura addui, Cirolana manorae, Cymodoce fuscina, Cymodoce pilosa, Elaphognathia bacescoi, Gnathia illepidus, Gnathia inopinata, Heptanthura cryptobia, Kupellonura serritelson, Metacirolana rotunda, and Pseudocerceis cf. seleneides). Three of these (four, when the cf. species is confirmed) are new records in the Mediterranean Sea (Apanthura addui, Cirolana manorae, Metacirolana rotunda, and Pseudocerceis cf. seleneides). Eight species (28.5%) can be considered non-indigenous (Apanthura addui, Cirolana manorae, Cymodoce fuscina, Metacirolana rotunda, Paracerceis sculpta, Paradella dianae, Pseudocerceis cf. seleneides, and Sphaeroma walkeri). This work also provides an inventory of known Mediterranean isopod fauna (excluding Epicaridea, Oniscidea, and brackish water Aselloidea), which total 295 species. The isopod fauna of various subregions of the Mediterranean, the Suez Canal, and the Red Sea/Gulf of Aden are compared, and the transit of species through the Suez Canal is discussed. The list of non-indigenous species in the Mediterranean Sea is updated to 23.