Copepod Eurytemoracaspica Sukhikh et Alekseev, 2013 (Crustacea, Calanoida) in Volga and Kama River Reservoirs

In 2013, a new species, Eurytemora caspica Sukhikh et Alekseev, 2013, was described from the northern part of the Caspian Sea. A thorough morphological analysis of Eurytemora from the Volga River basin by the original descriptors of the species has shown that E. caspica , rather than previously assumed E. affinis , actually inhabits the studied area. The species E. affinis itself was not detected in any sample. Analysis of the mitochondrial cytochrome oxidase subunit 1 gene (COI) has confirmed the species status of the studied populations from the Caspian Sea and some other areas of the Volga basin. The species is widespread throughout the Volga basin to the Kama Reservoir at the confluence of the Inva and Kosva rivers (58°52′ N) in the north and has penetrated to the mouth of the Kama River (55°12′ N) upstream the Volga. During summer, the abundance of the species in different parts of the Volga–Kama basin ranged from single findings to several thousand species per cubic meter.