Eudiaptomus transylvanicus and E. vulgaris (Copepoda: Calanoida: Diaptomidae): comparative morphology, distribution and ecology

Abstract

Two closely related, difficult to diagnose calanoid copepod species, Eudiaptomus transylvanicus (Daday, 1891) and E. vulgaris (Schmeil, 1898), were studied based on the new material from the Sura River floodplain (the Middle Volga region, European Russia). The redescriptions and illustrations of two species are provided. The main diagnostic differences between these species are refined. New characters useful in the identification of E. transylvanicus are proposed. The data on distribution and habitats of the two species are reviewed and briefly analysed.