Spumellarian, collodarian, and entactinarian radiolarians observed in sediment traps from the southern Ionian Sea (eastern mediterranean)

Abstract

Based on sediment trap material collected from the southern Ionian Sea (Eastern Mediterranean), this study describes and illustrates 54 radiolarian species, 48 of which are spumellarians, 3 collodarians and 3 entactinarians. The presence of Larcopyle buetschlii chenmuhongi, Phorticium polycladum, and Polysolenia collina is reported for the first time from the Mediterranean Sea. We also identified for the first time Spongodendron macrodoras in the eastern Mediterranean Sea, previously known only from the western Mediterranean. Despite their geographical proximity, only six species are in common with the radiolarian fauna of the Adriatic Sea. We reviewed the biogeographical distribution and the known depth habitat of all species identified here at the species level. Most of them are known from tropical to temperate regions, although we also encountered few species with cold-water affinities such as Lithelius minor, Lithelius nautiloides, Hexacromyum enthacanthum, Rhizosphaera mediana, and Spongodiscus resurgens. Most of the encountered species are surface to sub-surface dwellers, including several known symbiont-bearing species, and only few are deep-dwellers, such as Hexacromyum enthacanthum, Tetrapetalon echinaster, Lithelius nautiloides and Lithelius minor.