A team at the National and Kapodistrian University of Athens has identified a completely new genus and species of subterranean freshwater snail in southern Greece. The animal, named Cyllena hermes, lives its entire life underground in a specialized karst spring system and is adapted to near-total darkness, including loss of pigmentation and eyes.
The discovery was made in a highly restricted area in the Peloponnese, specifically within a single karstic spring near Mount Kyllini. The site lies at roughly 610 meters elevation in the Korinthia region, where groundwater emerges from carbonate bedrock and forms a small stream.
From there, the stream flows toward Lake Stymphalia, connecting to the broader underground hydrological network of the Stymphalia closed karst basin. Such systems can act as isolated “aquatic caves,” where species evolve under stable yet fragile conditions and dispersal is extremely limited.
Cyllena hermes is currently known from only this one locality, meaning its survival depends on the persistence of the local water source. Even minor changes in groundwater availability can reshape habitat conditions, affecting flow rate, water chemistry, and overall ecosystem stability in ways surface-dwelling species would not experience.
The researchers used these ecological constraints to assess conservation risk. Because the snail relies entirely on a single, isolated water supply, the species is classified as Vulnerable under IUCN Red List criteria, reflecting its susceptibility to drought and water extraction in neighboring areas.
Taxonomically, the team created a monotypic genus—a genus represented by only this single species—highlighting both its uniqueness and the narrow evolutionary context in which it was found. The names draw on ancient Greek mythology linked to the mountain where the snail lives.
The genus name Cyllena honors Cyllene (Κυλλήνη), a nymph associated with Mount Kyllini who, in myth, nurtured Hermes. The species epithet hermes pays tribute to Hermes (Ἑρμῆς), the messenger god said to have been born in a cave on Mount Kyllini, connecting modern science directly to the geography of the discovery.
Beyond its scientific novelty, the study underscores a broader message: Greece’s karst landscapes can contain hidden biodiversity that remains unrecorded in conventional surveys. At the same time, the work emphasizes how vulnerable these underground habitats are when water systems are pressured by climate variability and human use.
The full research details have been published in the peer-reviewed, open-access journal Subterranean Biology.
Subject of Research: Subterranean freshwater snail taxonomy and conservation
Article Title: From the dark to the light: A new genus and species of stygobiont hydrobiid (Caenogastropoda, Truncatelloidea) from southern Greece
News Publication Date: 18-Jun-2026
Web References: https://doi.org/10.3897/subtbiol.57.189090
References: Radea C, Protopapas D, Parmakelis A, Koskeridou E (2026) Subterranean Biology 57: 1–21. https://doi.org/10.3897/subtbiol.57.189090
Image Credits: Radea et al., 2026
Keywords: subterranean biology, karst spring, stygobiont, Hydrobiidae, new genus, new species, IUCN Vulnerable, Greece, Cyllena hermes
Tags: adaptation to darkness in cave speciescave-dwelling aquatic invertebratesCyllena hermesendemic species Greecefragile cave habitatsfreshwater snail conservationgroundwater-dependent specieskarst spring ecosystemnew genus and speciessubterranean biodiversitysubterranean freshwater snailunderground hydrological systems
