A new species of Pseudorientalia (Gastropoda: Hydrobiidae) from midwestern Trkiye with notes on Pseudorientalia natolica (Kster, 1853).

The members of the genus Pseudorientalia Radoman, 1983 are small hydrobiid species with characteristic features of the penis and female genitalia. The type locality of the genus is the southern Marmara region, northwestern Trkiye. In this study, sampling was carried out in the upper Sakarya River Basin, western-middle Anatolia to obtain hydrobiid specimens, which yielded a new Pseudorientalia. The shell, penis, and female genitalia of the new species are described. The measurement of some shell characters is compared with the other representatives of the genus from Trkiye, northern Greece, and some Aegean islands: Samos, Chios and Lesvos. In addition, notes on Pseudorientalia natolica are also given from examination of the type specimens.