From the dark to the light: A new genus and species of stygobiont hydrobiid (Caenogastropoda, Truncatelloidea) from southern Greece

A new stygobiont hydrobiid genus and species is described from the Stymphalia karst basin (Peloponnese, Greece). Cyllena hermes gen. et sp. nov. is distinguished from other valvatiform or valvatiform – planorboid stygobiont hydrobiids by a unique combination of shell and anatomical characters, supporting the establishment of a new monotypic genus. It is currently known from a single karstic spring connected to the subterranean hydrological network of the Stymphalia polje, indicating a highly localized distribution.

Following a precautionary approach, and in accordance with IUCN criteria, the species is here considered to qualify as Vulnerable (VU D 2). The discovery of the new genus contributes to the documentation of subterranean aquatic gastropod diversity in Greece and emphasizes the need for further targeted exploration of karst ecosystems in the region.