Two new snail species discovered in Montenegro’s threatened Komarnica Canyon

Deep in the limestone landscapes of northern Montenegro, scientists working alongside citizen volunteers have formally described two previously unknown species of land snail, one of which lives at the type locality of a canyon slated for flooding under a planned hydropower dam. The new species, named Cochlostoma (Turritus) dobrido and Cochlostoma (Turritus) komarnica, were discovered during structured biodiversity surveys in Durmitor National Park and the adjoining Komarnica Canyon, and their description in the Biodiversity Data Journal adds fresh weight to ongoing efforts to build a science-based conservation case for one of Europe’s most biodiverse karst regions.

The genus Cochlostoma is a familiar component of the malacofauna of limestone rocks throughout the countries surrounding the Mediterranean. These animals carry small to medium-sized conical shells and have been the subject of many older taxonomic studies that relied on shell shape, pigmentation and conchological details to delineate species. Recent work, however, has revealed that the taxonomic usefulness of shell characters is limited. Instead, the female reproductive anatomy paired with DNA sequence data reveals a far richer and clearer picture of the diversity hidden within the genus, showing that uniform shell morphology conceals surprisingly deep evolutionary divergences.

Within Cochlostoma, earlier research distinguished eight subgenera using evidence from conchology, anatomy and DNA. One of these, the subgenus Turritus, consists of at least 37 partly cryptic species distributed across the Italian and Balkan peninsulas, the eastern and western Alps, the southern coastal mountains of France and Spain, Sardinia and Sicily, with one species from the Algerian coast possibly also belonging to the group. Molecular phylogenetics show that Turritus is a strongly supported monophyletic group subdivided into two well-defined clades, A and B. Two populations from Clade B, found at high elevations in northern Montenegro and previously labelled only as ‘NFS142’ and ‘NFS143’, had been flagged as requiring further study before their species identity could be ascertained, because insufficient material was available at the time.

Between June 2018 and July 2025, researchers sampled extensively in the contiguous areas of the Komarnica Canyon and Durmitor National Park, where Cochlostoma populations are often dense and common on Triassic or Cretaceous limestone. During dry weather, specimens were found in crevices in the rocks and hidden under mosses and at plant roots, while empty shells were sieved from debris underneath vertical limestone faces and retrieved by direct inspection or flotation. During wet weather, the snails were found actively foraging on the rocks and in moss and lichen. Adult individuals were relaxed overnight in water and then transferred into 70% ethanol, with small tissue samples taken from the apical whorls of the shell and preserved in 96% ethanol for molecular work.

The fieldwork was carried out by mixed teams of local and international laypeople and taxonomists as part of a ‘taxon expedition’, in which so-called taxonomy tourists are guided by biodiversity experts through the entire process of species discovery and description. Using a portable field laboratory, the teams extracted DNA from snail tissue, amplified the cytochrome c oxidase subunit I and 16S mitochondrial barcoding regions, and sequenced the resulting amplicons with Oxford Nanopore MinION devices, with additional samples processed through Sanger sequencing in Leiden. Shell morphology was quantified with ImageJ from photographs taken through a Zeiss dissection microscope, capturing measurements such as shell height, body whorl width, rib inclination and rib density, alongside qualitative characters including umbilicus state, columellar lobe shape, shell colour and ribbing strength.

The first new species, Cochlostoma (Turritus) dobrido, is named after the Dobri Do highland plain in Durmitor National Park, where its holotype was collected at 1850 metres elevation in July 2024. Its shell is pale yellowish-grey without orange spots, bears 7.3 to 8.0 whorls, and measures 6.33 to 7.10 millimetres in height with a shell index of 2.37 to 2.58, making it relatively squat with a hidden umbilicus and weak radial ribs. The species has so far been reliably recorded, confirmed by both anatomy and DNA, from three localities on the Dobri Do highland plain, where it was found in high densities on limestone cliffs between 1680 and 2080 metres, sometimes syntopic with its newly described relative. The name was chosen by vote on the final night of the 2023 Taxon Expedition to Durmitor National Park.

The second species, Cochlostoma (Turritus) komarnica, carries the name of the Komarnica Canyon itself, where its holotype was collected from the left bank of the river at 730 metres elevation in July 2024. Its shell is also pale yellowish-grey without orange spots, but is more slender, measuring 5.12 to 5.79 millimetres in height with a shell index of 2.44 to 2.65, moderately strong radial ribs and a hidden umbilicus. The species appears to be endemic to Durmitor National Park and the adjacent Komarnica Canyon, with a remarkably broad elevational range from 730 to 1735 metres. Genetically and morphologically, it is closely related to Cochlostoma hallgassi, which occurs north of Naples and is separated geographically by the Adriatic Sea and the Italian peninsula, the two species differing chiefly by the pattern of two spiral rows of orange dots on the shell of the Italian relative.

The molecular analysis showed that the two new species are genetically quite distant from each other, at approximately eight percent based on two partial mitochondrial DNA loci, and are also well separated from Cochlostoma scalariniforme, which occurs in the same region. Conchologically, however, the separation from scalariniforme is difficult, which is why the researchers relied on DNA sequence data to confirm the identity of specimens found in the study area. Anatomically, the two new species are quite similar to each other, and much of the observed difference may reflect individual rather than species-level variability. Nonetheless, by considering a combination of conchological, genetic and anatomical features, the two new species can be distinguished from each other and from the other Cochlostoma species occurring in the area, including Cochlostoma pallgergelyi and Cochlostoma arnautorum.

Both new species were found sympatrically and, in some cases, syntopically with Cochlostoma scalariniforme as well as with each other, meaning that two species might occur in mixed populations at the same site. This, combined with the challenges of identifying individuals from shell characters alone, suggests that reliable distribution maps for each species will need to await further research, and it is entirely possible that more new species may turn up as sampling continues. The region in which Durmitor Mountain and Komarnica Canyon are located is a geologically and ecologically complex area with many canyons, plains, gorges and mountains, and many microhabitats across a wide elevational range, so local endemism in these slow-migrating snails may be even more widespread than currently documented.

The conservation implications are stark. Cochlostoma dobrido might be endemic to the Dobri Do highland plain and may be adapted to highland environmental conditions, meaning its populations could suffer if climate change continues to shift montane environmental zones upward. Cochlostoma komarnica faces a more immediate threat: while its higher-elevation populations lie within Durmitor National Park, those at lower elevation occur inside the continuity habitats of the Komarnica Canyon, which is threatened by a planned hydropower dam and reservoir. Should the project be realised, the type locality will flood and this population will perish. The researchers argue that construction of the Komarnica Dam should be prevented and that the canyon’s inclusion in the Durmitor UNESCO World Heritage Site should be persistently advocated, noting that slow-migrating gastropods are key indicators of habitat continuity and long-term ecological stability in these ancient karst landscapes.

Subject of Research: Two new Cochlostoma land snail species described from northern Montenegro

Article Title: Two new Cochlostoma species from the Durmitor and Komarnica regions of northern Montenegro ( Caenogastropoda , Cochlostomatidae )

Article References: Schilthuizen, M., Boomsma, R., Faes, S., Jousma, M., Buisman, J., Lankenau, D.-H., Kountouras, S., van den Broek, M., Hemelaar, E., Noomen, J., de Vries, R., Lopatriello, G., Limongi, A. R., Maestri, S., Kamchev, P., van Manen, S., Khalik, M. Z., Delledonne, M., Đokić, J., … Zallot, E. (2026). Two new Cochlostoma species from the Durmitor and Komarnica regions of northern Montenegro (Caenogastropoda, Cochlostomatidae). Biodiversity Data Journal, 14, Article e196955. https://doi.org/10.3897/bdj.14.e196955

Image Credits: AI Generated

DOI: 10.3897/BDJ.14.e196955

Keywords: Cochlostoma, Turritus, Montenegro, Durmitor National Park, Komarnica Canyon, Taxon Expeditions, biodiversity, conservation, gastropods, karst, species, Durmitor