Invasion of the common percarina Percarina demidoffii (Percidae, Perciformes) in the Dnieper River upstream

In December 2016, the common perсarina Percarina demidoffii Nordmann, 1840 has been evidentiary detected in the Dniprovske (Zaporizske) reservoir for the first time. Two specimens of percarina were caught in the rowing channel area (the upper part of the reservoir) near the Dnipro city. One individual was caught there in 2017 as well. The paper presents their morphological characteristics, as well as a comparison with specimens from the brackish waters of the Dniester estuary (the Black Sea). The preliminary data allow us to assume that differences in some plastic characters may have adaptive character in relation to the environment. There are no any meristic differences between these fishes. It is noted that the new finding of this fish species in the cascade of Dniprovske reservoirs allows us consider P. demidoffii as not mesohaline but as a freshwater-oligohaline species. The finding of the common percarina in the Dniprovske reservoir confirms a few earlier published data about the advance of this fish upstream of the Dnieper River and extends its current range. The presence of P. demidoffii as a new species for the fish fauna of the Dniprovske reservoir shows a continued active advance of the Ponto-Caspian fish species upstream of the cascade of reservoirs on the Dnieper River.