Synopsis of the terrestrial and freshwater gastropod fauna of southern Bahia, Brazil

The terrestrial and freshwater malacofauna of southern Bahia is little known, especially in comparison to the well-studied eastern portion of the state covered by remnants of Atlantic Forest. We present here a synopsis of all gastropod species known from the central southern region of Bahia state, known as ‘Centro-Sul Baiano’, focusing on four municipalities: Condeúba, Cordeiros, Mortugaba, and Piripá. The list herein contains data from the literature, historical material deposited in museum collections, and two recent expeditions undertaken in the region. The survey resulted in 21 species of gastropods, with nearly 700 voucher specimens (mostly freshwater) deposited in the collection of the Museu de Zoologia da Universidade de São Paulo (São Paulo, Brazil). Circa 30% of the species are non-indigenous; previously, the only known exotic in the region was Melanoides tuberculata (Müller, 1774). The family Achatinidae was the most diverse group in number of native species, while the typically diverse superfamily Orthalicoidea was represented by only two species.

First report of the freshwater gastropod Pettancylus tenuis (Bourguignat, 1862) (Gastropoda, Planorbidae) from Pune region, India

We present the first record of the freshwater gastropod Pettancylus tenuis from the Pune region of India. This species, which resembles a limpet, was found in November and December 2020 in a wetland formed near the confluence of Mula and Ram rivers in Pune city. The shell characters of the specimens match the available description of the species. The other records of this species from Maharashtra are nearly 150 km from Pune.

No effects of waterproof marking on the behaviour and growth of Physa acuta Draparnaud, 1805 (Gastropoda: Hygrophila: Physidae) in the laboratory

Physa acuta Draparnaud, 1805 is one of the most common freshwater gastropod species, with worldwide distribution. It is an effective periphyton grazer and a potential keystone species in shallow-water systems, where it can boost macrophyte well-being and thus help maintain high water clarity even in nutrient-rich habitats. P. acuta also has been extensively studied in ecotoxicological and behavioural investigations. Such investigations may require observations on individual snails. A method to distinguish individual snails in small-scale experiments is marking their shells with paint dots. However, such marking must not influence snail behaviour (nutritional, reproductive, respiratory, etc.) or growth to avoid confounding effects. Earlier investigations point to no or very limited effects of marking on aquatic and terrestrial snail survival, behaviour, and growth. We tested whether marking could affect the behaviour (as snail activity) and growth of P. acuta using a waterproof, oil-based, non-toxic, fine-point car-body paint marker. Snails were divided into a “marked” and an “unmarked” (control) group of ten snails each in an eight-day experiment. The marking had no effect on the snail activity or growth. The snails survived the experiment and produced egg clutches well beyond the eight-day period. The marking persisted without fading during and beyond the experimental period. Our results support earlier findings that the use of oil-based, non-toxic markers can assist in carrying out reliable observations on individual snails, including the small-bodied P. acuta. Combinations of two dots of different colours allow simultaneous observations on a high number of replicate individuals.

First freshwater gastropod preserved in amber suggests long-distance dispersal during the Cretaceous Period

Burmese amber continues to provide unique insights into the terrestrial biota inhabiting tropical equatorial forests during mid-Cretaceous time. In contrast to the large amount and great diversity of terrestrial species retrieved so far, aquatic biota constitute rare inclusions. Here we describe the first freshwater snail ever preserved in amber. The new species Galba prima sp. nov. belongs in the family Lymnaeidae, today a diverse and near globally distributed family. Its inclusion in terrestrial amber is probably a result of the amphibious lifestyle typical of modern representatives of the genus. The finding of a freshwater snail on the Burma Terrane, back then an island situated at some 1500 km from mainland Asia, has implications for the dispersal mechanisms of Mesozoic lymnaeids. The Cenomanian species precedes the evolution of waterfowl, which are today considered a main vector for long-distance dispersal. In their absence, we discuss several hypotheses to explain the disjunct occurrence of the new species.

Behavioral Biomarker Responses of Filopaludina bengalensis to Acute Copper Toxicity

As heavy metals are bioaccumulative and toxic in nature, increasing heavy metal levels in the environment is of great concern. The present study was aimed to assess the acute toxicity effects of copper on some behavioral attributes of Filopaludina bengalensis (locally known as ‘Genri’), a freshwater gastropod, under laboratory condition. Exposure to copper (0.50-2.0 ppm) for 96 h resulted in significant mortality. Recorded LC50 value at 96h was 0.586 ppm. The aggregation tendency, crawling activity and mucus secretion were observed at different exposure period upon acute exposure of copper (0.586 ppm).With the advancement of exposure period, gradual deaggregation was observed in snails of copper treated sets. There was statistically significant difference (P <0.01) in aggregation response and foot protrusion response at different span of exposure in copper treated groups. In copper treated sets, a substantial increase (P<0.01) in mucus secretion (%) was evident with time. Foot protrusion and movement was inhibited in copper treated groups. All three responses in the copper treated groups were significantly different (P <0.01) from that of control groups. The behavioral responses observed in this study of Filopaludina bengalensis could be used as biomarkers for copper contamination in any aquatic ecosystems.

Pseudobithynia ambrakis Glöer, Falniowski & Pešić 2010 (Gastropoda: Rissooidea: Bithyniidae), a new species from the Macedonian part of Dojran Lake

The recently described freshwater gastropod Pseudobithynia ambrakis Glöer, Falniowski & Pešić 2010 is reported from the R. North Macedonia for the first time. The species was previously known only from Lake Amvrakia in Greece, but it turned out to be present in Dojran Lake as well, only misidentified and recognized under different name, Bithynia leachii (Sheppard, 1823). In the following paper we present information about the species’ habitat and distribution. Photographs of the shell and male genitalia are also provided.

A survey of miRNAs involved in biomineralization and shell repair in the freshwater gastropod Lymnaea stagnalis

MicroRNAs (miRNAs) are a deeply conserved class of small, single stranded RNA molecules that post-transcriptionally regulate mRNA levels via several targeted degradation pathways. They are involved in a wide variety of biological processes and have been used to infer the deep evolutionary relationships of major groups such as the Metazoa. Here we have surveyed several adult tissues of the freshwater pulmonate Lymnaea stagnalis (the Great Pond Snail) for miRNAs. In addition we perform a shell regeneration assay to identify miRNAs that may be involved in regulating mRNAs directly involved in the shell-forming process. From seven mature tissues we identify a total of 370 unique precursor miRNAs that give rise to 336 unique mature miRNAs. While the majority of these appear to be evolutionarily novel, most of the 70 most highly expressed (which account for 99.8% of all reads) share sequence similarity with a miRBase or mirGeneDB2.0 entry. We also identify 10 miRNAs that are differentially regulated in mantle tissue that is actively regenerating shell material, 5 of which appear to be evolutionarily novel and none of which share similarity with any miRNA previously reported to regulate biomineralization in molluscs. One significantly down-regulated miRNA is predicted to target Lst-Dermatopontin, a previously characterized shell matrix protein from another freshwater gastropod. This survey provides a foundation for future studies that would seek to characterize the functional role of these molecules in biomineralization or other processes of interest.