Freshwater molluscs are key components of aquatic ecosystems, contributing to ecosystem functioning. However, their diversity in southern Tamil Nadu remains poorly studied, especially in lentic ecosystems. We surveyed 41 waterbodies across the Tenkasi, Tirunelveli and Thoothukudi districts of Tamil Nadu to document species composition and water quality variables. A total of 24 species belonging to 18 genera and 12 families were recorded, accounting for 11.2% of India's freshwater malacofauna. Gastropods dominated the assemblage (83%) compared to bivalves (17%). Gabbia travancoria and Idiopoma dissimilis were the most widespread species, whereas Pettancyclus tenuis and Corbicula striatella were restricted to single sites. Sundarapandipuram tank exhibited the highest richness with nine species. Physicochemical analysis revealed variation in conductivity, nutrients, and dissolved oxygen across sites, and CCA indicated that conductivity and nutrient enrichment were the primary drivers of species composition, with dissolved oxygen playing a secondary role. The frequent occurrence of pollution-tolerant and medically important taxa in human-use waterbodies highlights both ecological and public health concerns. This study provides the first regional checklist and highlights the need for long-term monitoring, habitat conservation, and integrated eco-health studies on freshwater molluscs.
This paper analyses the results of our own research from 2019 to 2025, as well as other available data on the shell colouration in C. nemoralis from different parts of Ukraine. Qualitative data from more than 70 localities (usually settlements, less often their environs) in 17 administrative regions were summarised. Quantitative data (7 regions, 28 localities, almost a hundred collection sites, and more than 13 thousand specimens) represent mainly the western part of the country, especially the city of Lviv and its immediate surroundings. It has been shown that western Ukrainian populations of C. nemoralis have, in general, a large phenotypic diversity and a very variable phenotypic composition. The latter can be considered characteristic of recently established populations outside the natural range. A comparison with similar data for other parts of Eastern Europe was made.
Zonites nikariae and Zonites chloroticus polycrates were previously recorded from Ikaria Island only as empty shells, collected over a century ago. Here, we report the first collection of living specimens of both taxa during a 2025 survey on the island. In the case of Z. nikariae, the collection of adult specimens enabled the first description of its reproductive system. Furthermore, two individuals of Z. chloroticus polycrates were found in Ikaria, marking the species’ rediscovery on the island 138 years after it was last documented. The confirmed presence of these populations is important amid the overall decline of the genus Zonites across the Aegean region. However, given that both taxa were found in sparse and localised populations, targeted conservation efforts and systematic monitoring are needed to secure their survival.
In this work, we provide replacement names for three fossil gastropod taxa described by Petar S. Pavlovi & cacute;, which are all currently junior primary homonyms. The newly introduced names include Gyraulus lacertula Goj & scaron;ina et Vuji & cacute;, nom. nov. (replacement name for Planorbis fragilis Pavlovi & cacute;, 1903, non Dunker, 1850), Gyraulus explanorbis Goj & scaron;ina et Vuji & cacute;, nom. nov. (replacement name for Planorbis verticilloides Pavlovi & cacute;, 1931, non Serres, 1851) and Micromelania megalomania Goj & scaron;ina et Vuji & cacute;, nom. nov. (replacement name for Micromelania subulata Pavlovi & cacute;, 1927, non Westerlund, 1902).
Ancylus fluviatilis (O. F. M & uuml;ller, 1774) was collected in July 2025 from a karstic, spring-fed tributary of the upper Munzur River Basin in eastern Turkey. The examined specimens exhibited the species' characteristic conical, limpet-like shell, measuring 5.8-7.6 mm in shell length (6.9 +/- 0.5 mm), 2.4-3.6 mm in shell height (3.1 +/- 0.3 mm), 4.4-6.6 mm in aperture width (5.5 +/- 0.4 mm), and 5.3-7.2 mm in aperture height (6.4 +/- 0.5 mm) (n = 20). The apex is subcentral, and the shell surface shows fine concentric growth lines with faint radial striations. Coloration is dark grey centrally, gradually fading to a yellowish margin. The habitat, characterised by clear, cold (13-16 degrees C), and fast-flowing water over a stone-cobble substrate, aligns with the species' rheophilic ecology previously documented in Europe and Anatolia. This study provides baseline data to support freshwater biodiversity assessments and future conservation studies of rheophilic gastropods in the region.
