Redescription and relationships of Eucyclops persistens (Copepoda: Cyclopidae) endemic to the Azov-Black Sea basin

The cyclopoids of the Ponto-Caspian region has been discussed in numerous articles and seminal monographs of the late V. I. Monchenko, yet relationships of this peculiar fauna to other regions are still poorly understood. Two subspecies of Eucyclops persistens known from interstitial waters in the Black sea region are redescribed here, based on the type material. Eucyclops persistens persistens (estuary zone of Caucasian rivers) and E. persistens tauricus (wells in Crimea) differ from each other in the lateral surface ornamentation of the caudal rami in female (naked, vs. short serra present), and the relative length of the dorsal caudal seta in both female and male (seta longer in E. persistens tauricus). Eucyclops persistens s.l. share some characters, such as the reduced “serra”on the caudal rami, reduced lateral pilosity of pediger 5, lack of (or few) hairs on the distal margin of P4 intercoxal sclerite, and long aesthetasc on the ninth antennulary segment in female, with some European subterranean taxa in the Eucyclops graeteri complex. Sparse morphological information on the graeteri-complex hinders a rigorous phylogenetic analysis. Future revision of the graeteri-complex might shed light on a Western/Central Europe – Ponto-Caspian connection during the evolution of these subterranean Eucyclops.