New localities and morphological contributions to two little-known endemic species, Pseudamnicola bilgini and Sheitanok amidicus (Gastropoda: Hydrobiidae), from SE Anatolia, Turkey

This study reports three new localities for two endemic microsnails, Pseudamnicola bilgini and Sheitanok amidicus (Caenogastropoda: Hydrobiidae), from Southeastern Turkey, and provides morphological descriptions of both species’ populations. Previously known from 16 and 12 localities, respectively, the distributions of P. bilgini and S. amidicus are now extended to include sites in Şırnak (Eskiyapı and Faki Teyran) and Mardin (Yardere Village). Two of the previously documented localities for S. amidicus – Tüllük Village spring (type locality) and Herbik spring – are no longer accessible due to their destruction. The three new localities, each characterised by clean, moderately flowing springs within dense woodlands, serve as the natural habitat for these snails, closely matching their ecological preferences. These hydrobiids were found in sympatry with Theodoxus sp. and Melanopsis sp. within the same spring ecosystem. Juveniles of all four species were observed in October 2024, suggesting that all of the species spawn at the beginning of autumn. Additionally, this study presents the first live images of P. bilgini, offering valuable insights into its morphological features for comparison.