Description of Stephos grieveae sp. nov. (Calanoida, Stephidae) from an anchialine cave in the Adriatic Sea

A new species of stephid calanoids copepod Stephos grieveae sp. nov. was collected from an anchialine cave on Mljet Island (Croatia). The new species can be distinguished from other Stephos spp. by a combination of the following features: last pedigerous somite slightly asymmetrical, female genital double-somite symmetrical in ventral view, about as long as wide, single operculum; antennules of both sexes are symmetrical, 24-segmented and very long, reaching almost to end of anal somite; antennal exopod 7-segmented; maxillule displays 13 armature elements on praecoxal arthrite; female fifth legs symmetrical, uniramous and 3-segmented, terminal segment very long armed with spinules distally along inner and outer margins, single small spine on anterior surface and spiniform process laterally; male fifth legs are uniramous and asymmetrically, right leg 4-segmented and left 5-segmented, segment 4 not swollen and segment 5 simple, crescent shaped and is connected to segment 4 at approximately one quarter of its length. The shorter part of segment 5 tapers into a heavy process, while the longer part forms a club-shaped, curved extension.