New Arietellid Copepods (Calanoida, Arietellidae) From Anchialine Caves In The Eastern Adriatic Sea

Two new species of calanoid copepods are described; Metacalanus adriaticus sp. nov. from an anchialine cave on Vis Island, and Paramisophria tvrtkovici sp. nov. from Orljak Cave, located in the lower part of River Krka estuary, near the town of ?ibenik (Croatia). This is the first report of arietellid copepods found in any anchialine cave along the coast of the Adriatic Sea. In M. adriaticus sp. nov. the antennules are asymmetrical in both sexes (the female left antennule is 18 -segmented, right 20-segmented; male left 16-segmented and right 20-segmented); the uniramous fifth legs of the female are 2-segmented; the terminal segment of the fifth leg in both sexes is the longest; and in the male the fifth leg exopod is 2-segmented. In P. tvrtkovici sp. nov. the antennules of both sexes are asymmetrical with the left antennule longer than the right, the female antennule is 21-segmented on both sides; the male left antennule is 19-segmented, the right 21-segmented; the armature of the terminal exopod segment of leg 1 is II, 2 ,2; the male fifth legs have a rudimentary endopod on the left leg, the third exopodal segment is smallest and bears three unequal processes on its outer margin, and the terminal spine is completely separated from the segment. On the right leg the third segment carries two short, unequal processes on its outer distal margin, as well as a long sigmoidal spine which is fused to the segment. It is inferred that, after the last glaciation, these new Arietellids moved out from their southern Adriatic refuge, colonizing first the anchialine habitats of the outer eastern Adriatic islands and then spreading along the coast.