Description of Bithynia gonensis sp. nov. (Gastropoda: Bithyniidae) from Gönen Çayi, north-western Türkiye

<span style="font-family: &quot;Titillium Web&quot;, HelveticaNeue-Light, &quot;Helvetica Neue Light&quot;, &quot;Helvetica Neue&quot;, Helvetica, Arial, &quot;Lucida Grande&quot;, sans-serif; font-size: 14px; text-align: justify;">This study aims to reveal the freshwater mollusc assemblages from 6 sites sampled along Gönen Çayı, a stream which flows into the southern Marmara Sea in north-western Türkiye. The stream was sampled using the multi-habitat sampling method with a hand net. Ten species of freshwater molluscs, most of which are widely distributed in Türkiye, were found in the study area. Among these taxa was an unidentified species of Bithynia, which was only present at 1 site. Its shell and anatomy were compared with other Bithynia species from Türkiye and neighbouring countries and found to differ, which revealed that it is a new species. The discovery of the new species increases the diversity of Bithynia in northern Türkiye to 4 species, and to 11 species for Türkiye. This paper highlights the diversity and endemism of freshwater molluscs in Türkiye and emphasizes the need for further research on the distribution of bithyniid species in the country.</span><br>