Both sexes of Ciplakastacus mersinensis gen. et sp. nov. (Copepoda, Harpacticoida, Leptastacidae) are described in detail based on intertidal material collected from the Mediterranean coast of Turkey (Mersin Province). Plesiomorphic character states displayed by the antenna and P1–P2 indicate Ciplakastacus diverged before the crown group Leptastacidae diversified. The new genus is placed in a basal clade (currently encompassing Archileptastacus and Meloriastacus) defined by eight synapomorphies: (1) caudal ramus with strongly developed seta I flanked by two elongate spinules; (2) caudal ramus with posteriorly directed spinous outgrowth of outer distal corner; (3) caudal ramus seta III vestigial; (4) P5 exopod and baseoendopod forming single plate in both sexes; (5) P2–P4 exp-3 with one outer spine; (6) dorsal posterior margin of anal somite bilaterally serrate; (7) rostrum triangular or bell-shaped, and (8) sexually dimorphic ornamentation on the anal somite. Within this clade Ciplakastacus appears most closely related to Meloriastacus on account of the shared presence of the extremely elongate second antennulary segment, an allobasis on the antenna, the strongly reduced accessory seta on the maxillipedal endopod, the subcylindrical sternal process between the maxillipeds and P1, and paired laterodorsal, posteriorly directed, serrate extensions on the anal somite. Both genera can be distinguished from each other by P5 morphology (both sexes), armature of P4 enp-2 and abdominal hyaline frill structure. The phylogenetic relationships between the basal taxa of the Leptastacidae are briefly outlined. |
