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The study of the Neolithic period in the Lake Eyasi Basin was dominated by attempts to formulate the area’s chronology, mobility, settlement patterns, subsistence, and cultural capabilities of Neolithic people as attested by domesticated animals, pottery, and lithic artefacts. Occasionally, studies on molluscs were mentioned, but rarely described in detail. Neolithic sites across the Lake Eyasi Basin have yielded remains of both terrestrial (gastropods) and freshwater mollusc shells (mussels). The abundance of mollusc shell remains in the archaeological records of the Lake Eyasi Basin have played a great role in chronological settings, mobility and community integrations, studies of settlement patterns, and other analyses. Mollusc remains have often been widely interpreted as a food supplement to other reliable food resources such as meat, vegetables and fish. Archaeological excavations and detailed analysis of the shells from Mumba rock shelter, Jangwani 3 and Laghangasimjega 2 have shown that molluscs played different roles. They were effectively used in tool manufacturing, as practical implements for handling objects, as scraping tools, as harpoons for fishing weapons, and sometimes for symbolism and in rituals. Terrestrial and freshwater molluscs coexisted in the Lake Eyasi Basin and were utilised equally by the Neolithic people during the Mid-Holocene period. Keywords: Mollusc shells; Neolithic; Lake Eyasi Basin; Northern Tanzania

Biological invasions are common among freshwater molluscs, with the North American planorbid gastropod Gyraulus parvus being reported from Europe (Germany) by the 1970s. It has since spread across Central and Western Europe, mostly living in artificial and highly modified habitats. However, considerable conchological and anatomical similarity exists between it and the native European G. laevis. Using four other European and one North American Gyraulus species as outgroups, separate phylogenetic analyses using mitochondrial and nuclear DNA sequences show that G. parvus and G. laevis are in fact part of the same species-level clade, with the former having nomenclatural priority. However, the structure within the mitochondrial tree suggests a North American origin of the invasive populations. It also makes it possible to track down the distribution of both races. Although native and non-native races in Europe tend to possess some differences in conchology and ecology, the degree of overlap makes it impossible to accurately distinguish between them without the DNA barcode data. Our results change the outlook on the conservation of the rare native race. While interspecific competition among snail species is rare, invasion on an intraspecific level may represent a serious threat for native populations.

Molluscs are among the most diverse and widespread animal groups in freshwater habitats. Unfortunately, like most freshwater taxa, they are decreasing dramatically and are now among the most threatened animals on Earth, with many species already extinct or on the brink of extinction. Here, we review our current knowledge on the biodiversity and conservation of freshwater molluscs using the concept of knowledge shortfalls. We focus on seven previously proposed key shortfalls to review and analyse existing knowledge gaps relating to (1) taxonomy, the Linnean Shortfall; (2) distribution, the Wallacean Shortfall; (3) abundance and population dynamics, the Prestonian Shortfall: (4) evolution, the Darwinian Shortfall; (5) abiotic tolerances, the Hutchinsonian Shortfall; (6) traits, the Raunkiaeran Shortfall; and (7) biotic interactions, the Eltonian Shortfall. In addition, we address a new shortfall, which relates to the application and effectiveness of conservation measures, including assessments, methods, funding, and policies, the Ostromian Shortfall. Based on our review, we provide recommendations and suggest pathways to overcome these existing shortfalls. This work also introduces the articles in this special issue of Hydrobiologia, which represent key contributions to the First International Freshwater Mollusk Conservation Society Meeting held in Verbania, Italy, in 2018.

The paper presents results on the analysis of the taxonomic structure of the trematode fauna of the Ukrainian Polissia. It was found that the trematode fauna of freshwater molluscs in the Ukrainian Polissia is represented by 62 species. We supplemented the species composition of larvae of trematodes in the region with 23 species, 13 of which were first recorded in Ukraine. The results showed that the number of trematode species the definitive hosts of which are fishes have decreased. According to the obtained data, the most abundant trematode species of freshwater molluscs in the Ukrainian Polissia are those of the families Echinostomatidae, Plagiorchiidae, Diplostomidae, and Notocotylidae. The combined analysis of literature and original data revealed that in the basis of the regional trematode fauna of molluscs are species of the families Echinostomatidae (13 species) and Plagiorchiidae (10 species), which make up almost one-third of the total number of trematode larvae detected. A quite large portion of larvae belong to species of the families Notocotylidae (8 species), Strigeidae (7 species), Diplostomidae (5 species), and Haematolechidae (5 species). Most families (Diplodiscidae, Opisthorchiidae, Leucochloridiomorphidae, Prostogonimidae, Cathaemasiidae, Cyclocoelidae, Prohemistomatidae, and others) are represented only by 1–2 species. In freshwater molluscs of the studied region, we have found only 38 % of trematode species recorded in definitive hosts. Species found in vertebrate animals of the region potentially can also occur in intermediate hosts, but most of these species parasitize in birds that could be infected in other areas. When comparing the taxonomic structure of the trematode fauna of the Polissia with other well-studied regions of Ukraine (Northern Pryazovia and Crimea), some specifics were noted between them. In particular, it was found that the most abundant trematode species in the region as well as in the whole of Ukraine are those of the families Echinostomatidae, Plagiorchiidae, Diplostomidae, Notocotylidae, and Strigeidae. The obtained data allow considering that the trematode fauna of freshwater gastropods of the Ukrainian Polissia is an integral part of the Central European fauna of trematodes.

Based on the literary and personal data, as well as collections of the State Museum of Natural History of the NAS of Ukraine and the Zoological Museum of the Ivan Franko National University of Lviv, the taxonomic composition and peculiarities of the spatial distribution of gastropods and bivalve molluscs in Western Ukraine have been analyzed. Species lists have been drawn up for the Volhynian (Western) Polissia, Volhynian Upland, Male Polissia, Roztochya and Opillya, Western Podillia, Central (Northern) Podillia, Prut-Dnister interfluve, Ciscarpathian, Transcarpathian lowland and mountainous part of the Ukrainian Carpathians. It is established that in the west of Ukraine, 74 autochthonous and 6 adventitious freshwater molluscs with generally recognized species status, belonging to 35 genera and 15 families, can be considered as reliably registered. Adventitious to Western Ukraine are Potamopyrgus antipodarum, Physella acuta, Menetus dilatatus, Dreissena polymorpha, D. bugensis, Sinanodonta woodiana. Additional confirmation requires the presence of Lithoglyphus pyramidatus, Omphiscola glabra, Physella heterostropha, Planorbis carinatus, Pisidium conventus, P. tenuilineatum. Not taking into account the Central Podillia, poorly researched by malacologists, a distinctly pronounced decrease in the species richness of freshwater molluscs is observed only in the mountainous part of the Ukrainian Carpathians (38 species, 17 genera, 8 families), with the presence of some specific components of freshwater molluscs complexes (small gastropods of the genera Bythinella і Paladilhiopsis). The richest taxonomic composition of freshwater molluscs was noted for Volhynian Polissia: 67 species, 29 genera, 15 families. It has been found that most freshwater molluscs are evenly distributed throughout the plain and foothill territories of Western Ukraine. Only few species can be considered as specific components of freshwater malacocomplexes for one of the physical-geographical areas or river basins. A number of species that are not present in the malacological collection of SMNH NASU, as well as the territories poorly represented in it, have been identified. The results obtained will be taken into account when further collecting the museum collection.

The purpose of the research to study the mixed course of sheep infection, caused by pathogens of fasciolosis and paraphistomatosis, in the conditions of Samarkand and Tashkent regions. Materials and methods. The research material was fallen and forcibly killed sheep from two regions of Uzbekistan, simultaneously infected by Fasciola gigantica and Paramphistomum spp. (Gastrothylax crumenifer, Calicophoron calicophorum). The animals' liver was subjected to complete helminthological dissection, followed by the presence of young immature in the parenchyma, and in the bile ducts – sexually mature fasciola. To detect pathogens of paramphistomatosis, we examined the scar and mesh, and, if necessary, the mucous membranes of the abomasum and the initial part of the small intestine. To kill the collected F. gigantica and complete bleeding with a Paramphistomum spp., they were kept in water for one and three to four days, respectively. After they took their natural form, their type, age and number were determined, and then fixed in Barbagallo fluid. If necessary, coprological studies of sheep and malacological studies of biotopes of freshwater mollusks, intermediate hosts of the studied trematodes, were carried out. Results and discussion. In recent years, cases of a mixed course in sheep fasciolosis (F. gigantica) and paramphistomatosis in farms of Uzbekistan have become more frequent. When opening the liver of the fallen sheep, up to 278 specimens were found immature F. gigantica and up to 3994 sp. G. crumenifer. In some farms, the death of individual owners' sheep from calicophorosis caused by C. calicophorum was observed with an intensity of infection of 592 sp. of C. calicophorum.

Acknowledgements The authors acknowledge the two anonymous reviewers for their useful comments that improved the manuscript. Financial support for the excavations in Neumark‐Nord 2 was provided by the Lausitzer Mitteldeutsche Braunkohlengesellschaft mbH, the Landesamt fur Denkmalpflege und Archaologie Sachsen‐Anhalt (Harald Meller, Susanne Friederich), the Romisch‐Germanisches Zentralmuseum Mainz, the Leids Universiteits Fonds ‘Campagne voor Leiden’ program and the Netherlands Organization for Scientific Research (N.W.O.).

Since the end of the 19th century, the circumpolar fauna of freshwater Mollusca has not been reviewed despite the substantial increase of knowledge on this subject. A review of the freshwater mollusks of the Arctic based on an analysis of published data, own results and examination of museum collections is presented. 104 species of Mollusca have been registered, which constitutes less than 2% of the global diversity. The actual diversity of the Circumpolar freshwater molluscs may lie between 100 and 120 species. No endemic taxa are found in the Arctic. The most species-rich Arctic subregion is Siberia, whereas the North America maintains the poorest fauna. The aquatic malacofauna of Beringia is similar to that of North America, and Beringia as a biogeographic region constitutes a part of the Nearctic. The ways of formation of the Circumpolar malacofauna are discussed, with evaluation of dispersal, adaptation, and environmental filtering as the faunogenesis factors. The number of non-alien species in the Circumpolar freshwater malacofauna remains very low, and only one reliable occurrence of an alien species is known. Among the Arctic molluscs only three have a conservation status other than ‘least concern’ or ‘data deficient’, whereas most resident species are widespread and abundant.

The first in-depth revision of a lacustrine freshwater mollusc fauna of the Serbian Lake System (SLS) is carried out. We describe and discuss well-preserved faunas from two localities in central and southern Serbia (Mađere and Medoševac), along with the reinvestigation of type material of several species described in the late nineteenth and early twentieth centuries. Our revision yields 14 species of gastropods, with the families Hydrobiidae (six species) and Planorbidae (four species) being most abundant, along with one species each of Neritidae, Melanopsidae, Bithyniidae and Bulinidae, as well as two dreissenid bivalve species. Three of the hydrobiid gastropods are new to science, Prososthenia milosevici sp. nov., Prososthenia? naissensis sp. nov., and Prososthenia rundici sp. nov., and so is the bivalve Trigonipraxis madjerensis sp. nov. The present study results in 12 lectotype designations, 10 new generic combinations, and 10 new junior synonyms. About four-fifths (81.3%) of the species are endemic to the SLS, which is slightly higher than the overall SLS endemism (71.4%). The composition at the genus and family level overlaps strongly with the slightly older faunas of the Dinaride Lake System in Croatia and Bosnia and Herzegovina, as well as that of the late Miocene Lake Pannon. Its stratigraphically intermediate position and geographical proximity suggest that the SLS was a stepping stone for many of the mollusc lineages, some of which are found only in those systems.

From 2014 to 2019 at more than 100 localities freshwater molluscs were collected along the basin of Moulouya River and Oriental Region of Morocco. These samples revealed two new hydrobiid species which are described here. One new species of Islamia and one species of a new genus. Photos of the holotypes are presented in addition to the penis morphology of the new genus and a map of the sampling area with the type localities.

Based on the literary and personal data, as well as collections of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv City, the peculiarities of the recent spatial distribution of the freshwater molluscs – in the landscape zones and main river basins of Ukraine – have been analyzed. In both cases, relatively weak spatial differentiation of freshwater malakofauna was detected.

Background Sound knowledge of the abundance and distribution of intermediate host snails is key to understanding schistosomiasis transmission and to inform effective interventions in endemic areas. Methods A longitudinal field survey of freshwater snails of biomedical importance was undertaken in the Niger River Valley (NRV) between July 2011 and January 2016, targeting Bulinus spp. and Biomphalaria pfeifferi (intermediate hosts of Schistosoma spp.), and Radix natalensis (intermediate host of Fasciola spp.). Monthly snail collections were carried out in 92 sites, near 20 localities endemic for S. haematobium. All bulinids and Bi. pfeifferi were inspected for infection with Schistosoma spp., and R. natalensis for infection with Fasciola spp. Results Bulinus truncatus was the most abundant species found, followed by Bulinus forskalii, R. natalensis and Bi. pfeifferi. High abundance was associated with irrigation canals for all species with highest numbers of Bulinus spp. and R. natalensis. Seasonality in abundance was statistically significant in all species, with greater numbers associated with dry season months in the first half of the year. Both B. truncatus and R. natalensis showed a negative association with some wet season months, particularly August. Prevalences of Schistosoma spp. within snails across the entire study were as follows: Bi. pfeifferi: 3.45% (79/2290); B. truncatus: 0.8% (342/42,500); and B. forskalii: 0.2% (24/11,989). No R. natalensis (n = 2530) were infected. Seasonality of infection was evident for B. truncatus, with highest proportions shedding in the middle of the dry season and lowest in the rainy season, and month being a significant predictor of infection. Bulinus spp. and Bi. pfeifferi showed a significant correlation of snail abundance with the number of snails shedding. In B. truncatus, both prevalence of Schistosoma spp. infection, and abundance of shedding snails were significantly higher in pond habitats than in irrigation canals. Conclusions Evidence of seasonality in both overall snail abundance and infection with Schistosoma spp. in B. truncatus, the main intermediate host in the region, has significant implications for monitoring and interrupting transmission of Schistosoma spp. in the NRV. Monthly longitudinal surveys, representing intensive sampling effort have provided the resolution needed to ascertain both temporal and spatial trends in this study. These data can inform planning of interventions and treatment within the region.

Pipelines, mechanisms and hydraulic structures laid on the bottom of freshwater bodies are exposed to massive exposure of fouling organisms - mollusks Dreissena polymorpha . Such fouling hinders the equipment operation and increases the corrosion of materials, besides, utilization of mollusks ( Dreissena polymorpha ) requires financial expenditure. Therefore, to solve the problem, dreissena was suggested to be used as a raw material for producing enzymatic hydrolyzate. The data of the mass-size and chemical composition of the raw materials (dreissena flesh) are presented. During the analysis of the model of a 2-factor experiment (the amount of enzyme preparation and the duration of fermentolysis were taken as factors) there was defined the optimal amount of enzyme (bacterial protease - protozyme). The comparative analysis of a control sample (without adding the enzyme) and enzymatic hydrolyzates of dreissena was carried out. There was stated the increase in protein content (3.7-17.8%), in dry matter (7.0-22.7%), amine nitrogen (446.2-158.6 mg/100 g). The periods of the most intensive increase in the degree of hydrolysis (during the first 2 hours of enzymatic hydrolysis by 2.8% and further 3-4 hours by 1.2%), as well as periods of values stabilization (during 2-3 hours and after 4 hours of enzymatic hydrolysis an increase by 0.6% on average). The change in the optical density of hydrolyzate solutions and their TCA-filtrates has been studied, which helped to compare the degree of protein destruction. There has been presented the technological chart of producing enzymatic hydrolyzates from dreissena with following conditions for fermentolysis: temperature 50 ºС, water ratio 1:1, quantity of enzyme protozyme 0.1% to the mass of blanched dreissena with valves, duration 3-4 hours.

Mapa del riesgo de contraer schistosomiasis urogenital provocada por Bulinus truncatus (Audouin, 1827) (Mollusca Gastropoda, Bulinidae) en España y Portugal Se da a conocer el mapa de la distribución geográfica de Bulinus truncatus en España y Portugal en el que se recopilan las localidades históricas y actuales, que coincide con el mapa del riesgo de contraer schistosomiasis urogenital provocada por este caracol de agua dulce. Se revisan las muestras de esta especie depositadas en el Museu de Ciències Naturals de Barcelona y en el Museo de Ciencias Naturales de Madrid, así como datos propios, incluidas algunas aportaciones inéditas. Este mapa permitirá conocer el área óptima de esta especie y determinar las zonas de mayor riesgo de contraer schistosomiasis urogenital en los dos países. Se pone de manifiesto que el cambio global y el cambio climático pueden favorecer la presencia tanto del vector (B. truncatus) como del parásito (Schistosoma haematobium) en España y Portugal., We present a geographical distribution map of Bulinus truncatus based on historical and current localities in Spain and Portugal, that corresponds to the risk map of urogenital schistosomiasis for this freshwater snail. We reviewed samples of the species deposited at the Museu de Ciències Naturals of Barcelona and the Museo Nacional de Ciencias Naturales of Madrid, together with our own data, including some unpublished contributions. This map will help determine the optimal area for this species and identify areas of greatest risk for urogenital schistosomiasis in the two countries. We emphasize that global change and climate change may favour the presence of both the vector (B. truncatus) and the parasite (Schistosoma haematobium) in Spain and Portugal., Mapa del riesgo de contraer schistosomiasis urogenital provocada por Bulinus truncatus (Audouin, 1827) (Mollusca Gastropoda, Bulinidae) en España y PortugalSe da a conocer el mapa de la distribución geográfica de Bulinus truncatus en España y Portugal en el que se recopilan las localidades históricas y actuales, que coincide con el mapa del riesgo de contraer schistosomiasis urogenital provocada por este caracol de agua dulce. Se revisan las muestras de esta especie depositadas en el Museu de Ciències Naturals de Barcelona y en el Museo de Ciencias Naturales de Madrid, así como datos propios, incluidas algunas aportaciones inéditas. Este mapa permitirá conocer el área óptima de esta especie y determinar las zonas de mayor riesgo de contraer schistosomiasis urogenital en los dos países. Se pone de manifiesto que el cambio global y el cambio climático pueden favorecer la presencia tanto del vector (B. truncatus) como del parásito (Schistosoma haematobium) en España y Portugal.

This study focused on finding of freshwater molluscs in Holocene sediments outcropping in western Eritrea. Three species of gastropods were found in calcareous sediments at the bank of a tributary river named Shatera River, within the license of Bisha Mines, they are Melanoides tuberculate (O. F. Müller, 1774), Bulinus globosus (Morelet, 1866) and Indoplanorbis exustus (Deshayes, 1833). The 14C dating on the shells of I. exustus and B. globosus was also carried out. The age dating result showed (9326-9134 cal yr BP) and (9134-8999 cal yr BP) respectively, of which are in the mid-Holocene epoch (11,000–5000 yr BP). This epoch is best known for it was a time when the northern and eastern part of Africa experienced a warm and humid climate. Among the freshwater molluscs, the existence of Melanonids tuberculate makes it more significant, for its widespread occurrence in Quaternary deposits throughout Africa and Asia in both fresh and highly evaporated lakes. This is suggestive of the considerable development of the lacustrine environment in the western part of Eritrea, which at present has disappeared.

First records of invasive bivalve freshwater mollusc species Mytilopsis leucophaeata (Conrad, 1831) and Corbicula fluminalis (O. F. Müller, 1774) in Georgia are reported. No native or alien extant dreissenid species have ever been recorded form this region so far. A finding of C. fluminalis in Georgia is also a new record for the country though this species inhabits the rivers of adjacent Azerbaijan. Apart from two mentioned bivalve molluscs three non-indigenous gastropod species are registered from Georgia: freshwater Ferrisia californica (Rowell, 1863) and Physella acuta (Draparnaud, 1805) and land snail Eobania vermiculata (O. F. Müller, 1774).

Freshwater mollusc diversity has repeatedly been found to peak in lowland stagnant waters, which are highly exposed to human-made degradation and the spread of non-native species. Despite the increasing loss of these habitats, little is known about the main predictors of their mollusc diversity patterns. Therefore, we aimed to determine the environmental drivers of mollusc assemblage variation between and within sites by sampling 62 water bodies in the Dyje River floodplain (south-eastern Czechia). We measured 14 environmental variables, categorized as site-specific or plot-specific. Species richness and abundances were analysed by GLM and GEE; species compositional variance was assessed by NMDS and db-RDA ordinations. Mollusc species richness, ranging between 0 and 15 species per site, and abundance sharply decreased towards high trophy sites, with the chlorophyll-a concentration and water pH highly correlated with species counts. Species compositional variation was driven mainly by water trophy and the quality of organic detritus. Site heterogeneity turned out to significantly control local assemblages of molluscs, while the presence of individual species seemed to be filtered by site trophy and the shoreline length. Thus, to maintain high regional diversity of aquatic molluscs in lowland agricultural landscapes, the presence of low trophy sites seems to be essential.

Summary Freshwater snails serve as one of trematodes’ intermediate hosts. Previous studies on trematode larval stages in the Philippines have largely focused on species with public health importance. This study sought to investigate the prevalence of cercarial morphotypes in several freshwater snail species found in different habitat types (rice field, irrigation canals, and residential area) in selected agricultural areas in Los Baños and Bay in Laguna. Cercarial emergence was induced through exposure to artificial light. A total of 2,720 freshwater snails were collected and were represented by seven species, namely, Melanoides tuberculata Muller 1774 (n = 1229), Radix quadrasi von Moellendorf (n = 630), Tarebia granifera Lamarck, 1816 (n = 417), Pomacea canaliculata Lamarck 1819 (n = 257), Vivipara angularis philippinensis Nevill (n = 18), Stenomelania sp. (n = 104), Thiara scabra Muller 1774 (n = 65). A 2.57 % over-all prevalence was recorded; the infected snail species were M. tuberculata (2.21 %), R. quadrasi (0.21 %), T. granifera (0.11 %). Four cercarial morphotypes, namely, Parapleurolophocercous cercaria (1.80 %), Virgulate xiphidiocercaria (0.26 %), Megaluruous cercaria (0.29 %), and Echinostome cercaria (0.22 %) were recovered from the infected snail species. Prevalence of cercarial infection was significantly different (p < 0.05) among habitat types.

River floodplain ecosystems host one of the highest freshwater molluscan biodiversity on Earth. However, multiple human disturbances, such as loss of hydrological connectivity and deterioration of water quality, are seriously threatening most floodplain lakes throughout the world. Given the high imperilment rate of freshwater molluscs but the scarcity of studies examining the anthropogenic effects on this fauna, we test the response of mollusc assemblages to river-lake disconnection and eutrophication in 30 lakes in the Yangtze River floodplain, China. The species richness of entire Mollusca, Gastropoda and Bivalvia and 6 dominant families were all much lower at disconnected lakes than that in connected lakes, and decreased with increasing water eutrophication. The assemblage structure differed significantly among four lake groups for datasets based on entire Mollusca, Gastropoda and Bivalvia, indicating the serious impacts of hydrological disconnection and eutrophication. Moreover, the connected lakes showed significantly lower values of average taxonomic distinctness (Δ+) but higher values of variation in taxonomic distinctness (Λ+) than disconnected lakes. Such variations were triggered by the extirpation of congeneric and endemic species (mainly from families Unionidae and Viviparidae), which giving a waring of the loss of mollusc endemism in this region. In general, the present study showed that river-lake disconnection and deterioration of water quality resulted in serious biodiversity declines of both gastropods and bivalves in the Yangtze River floodplain lakes. A systematic approach including restoration of river-lake connectivity and habitats and improvement of water quality should be implemented in the conservation planning in this large river floodplain.

OBJECTIVES: Identify freshwater mollusks and trematode larvae from drainage ditches in the Municipality of Peruibe, Sao Paulo State, Brazil, and describe the morphology of emerged larvae. MATERIALS AND METHODS: Mollusks were collected from 53 ditches. In the laboratory, the specimens were morphologically identified, and parasitological analysis was carried out to determine and describe the larvae. RESULTS: 5,969 mollusks belonging to the families Planorbidae, Lymnaeidae, Physidae, Thiaridae, and Ampullariidae were collected. The parasitological analysis of the mollusks revealed nine different larvae corresponding to the following seven types of cercariae: xiphidio cercariae, echinostome cercariae, strigea cercariae, brevifurcate pharyngeate distome cercariae, brevifurcate apharyngeate distome cercariae, pleurolophocercous cercariae, and amphistome cercariae. Biomphalaria tenagophila (d'Orbigny, 1835) was susceptible to eight of the nine cercariae found, and six specimens of mollusks were parasitized by Schistosoma mansoni Sambon, 1907. CONCLUSION: It is fundamental to establish malacological control and surveillance programs in vulnerable areas when mollusks, intermediate host of parasites of medical and veterinary importance, colonize these environments, especially when infected with S. mansoni larvae.

Molluscs are the most important resources among all the seafood items in South-East Asian countries. However, very little information available on nutritional value of molluscs in these regions. In this study, we evaluated the 7 economically important species of molluscs in terms of proximate composition, amino acids profile, fatty acids profile, cholesterol and heavy metal contents in the bivalves (mussels, oysters, clams and cockles) and univalve (snail) collected from freshwater and marine environments of Bangladesh. The results of the proximate analyses revealed that significantly higher amount of crude protein contents were present in marine water oysters, clams and cockles (59.3 ± 0.3 to 75.4 ± 0.2%) than the freshwater mussels and snail (36.9 ± 0.4 to 49.6 ± 0.6%) on dry matter basis. However, carbohydrate contents were significantly higher in freshwater mussels and snail (30.2 ± 0.9 to 57.3 ± 0.2%) compared to the marine water bivalves (8.1 ± 0.4 to 20.2 ± 0.6%). Crude lipid contents were ranged from 2.5 ± 0.2 to 11.2 ± 0.1% and ash from 11.4 ± 0.1 to 16.8 ± 0.6% among the bivalves and snail species. The amino acid contents were comparatively higher in marine water bivalves than their freshwater counterparts. Saturated fatty acid contents were found to be higher in marine water bivalves than the freshwater mollusc species. The results also show that the omega-3 (eicosapentaenoic acid, EPA and docosahexaenoic acid, DHA) fatty acids were comparatively higher in oysters, clams and cockles in marine water than those in freshwater mussels and snail. However, omega-6 fatty acids like linoleic acid (LA), α- linolenic acid (ALA) and arachidonic acid (ARA) were higher in freshwater mussels and snail than in the marine bivalves. The n-3/n-6 ratio were significantly higher in oysters and cockle species than the other groups of bivalves and snail. The index of atherogenicity and index of thrombogenicity of the mollusc species ranged from 0.74 ± 0.1 to 1.74 ± 0.2 and 0.5 ± 0.1 to 2.6 ± 0.2, respectively. The results show that marine water bivalves contained higher amount of potassium, sodium, iron, chlorine especially oyster species contained significantly higher iodine than the freshwater bivalves and snail. However, freshwater mussels and snail showed significantly higher amount of zinc contents than the marine bivalves. The heavy metal contents such as arsenic, chromium and mercury were absent or present in very tiny amounts among the mollusc species. Significantly higher amount of cholesterol was present in marine bivalves and freshwater snail species than the freshwater mussels. Overall, the results indicate that marine bivalves can be good sources of high quality protein and lipid especially EPA and DHA. On the other hand, freshwater mussels and snails also could be good sources of protein, LA and ARA but scarcity of EPA and DHA., Seafood; Nutritive value; Bivalves; Macronutrients; Micronutrients; Heavy metals

The diversity and distribution of freshwater molluscs is poorly studied in the Republic of Georgia, due to the scarcity of field studies during the last 50 years. Here, we present the results of the first concerted investigation of freshwater mollusc biodiversity in the Javakheti Highlands, in the southern, mountainous region of Georgia. In total, we were able to collect 22 species from 42 sampling localities, including different kinds of freshwater habitats. Amongst the 22 collected species, 12 were recorded for the first time from Javakheti. From the newly-recorded species,Bathyomphalus contortusis a new country record, whose identity is supported by 16S rRNA sequence data.

With the biodiversity crisis continuing unchecked, we need to establish levels and drivers of extinction risk, and reassessments over time, to effectively allocate conservation resources and track progress towards global conservation targets. Given that threat appears particularly high in freshwaters, we assessed the extinction risk of 1428 randomly selected freshwater molluscs using the IUCN Red List Categories and Criteria, as part of the Sampled Red List Index project. We show that close to one-third of species in our sample are estimated to be threatened with extinction, with highest levels of threat in the Nearctic, Palearctic and Australasia and among gastropods. Threat levels were higher in lotic than lentic systems. Pollution (chemical and physical) and the modification of natural systems (e.g. through damming and water abstraction) were the most frequently reported threats to freshwater molluscs, with some regional variation. Given that we found little spatial congruence between species richness patterns of freshwater molluscs and other freshwater taxa, apart from crayfish, new additional conservation priority areas emerged from our study. We discuss the implications of our findings for freshwater mollusc conservation, the adequacy of a sampled approach and important next steps to estimate trends in freshwater mollusc extinction risk over time., The authors would like to acknowledge the Esme ́e Fairbairn Foundation (NIDR and MB) and the Rufford Foundation (MB) for their generous support. MV is supported by the Russian Fund for Basic Research (project No. 19-04-00270).

Background In this study, we clarify the classification of museum specimens of the family Viviparidae , which is composed of six species/subspecies in Japan, including three endangered species. We examined Viviparus sclateri specimens from the Tomotaro Iwakawa collection (1855-1933) in the National Museum of Nature and Science, Tokyo. The Iwakawa's collection was catalogued in 1919 and Viviparus sclateri , labelled with Naga-tanishi, the current Japanese name for H. longispira , which was, at the time, equivalent to Viviparus sclateri , was listed in this catalogue. The catalogue noted localities of Viviparus sclateri (Naga-tanishi) from outside Lake Biwa, including occurrences in Lake Kasumigaura and Lake Suwa. However, Heterogen longispira (Naga-tanishi) is currently considered to be endemic to Lake Biwa drainage. The actual status of Viviparus sclateri in Iwakawa (1919) has not been clarified until now. New information Our examination revealed that Viviparus sclateri from Iwakawa’s catalogue included H. japonica , H. longispira and Sinotaia quadrata histrica , based on current taxonomy. Specimens assigned to H. longispira occurred only in Lake Biwa drainage. Heterogen japonica was confirmed to be present in all lots and some H. japonica from Lake Suwa had a distinctive morphology. Sinotaia quadrata histrica was only confirmed to occur in Lake Suwa. Furthermore, some specimens from southern Lake Biwa and the Seta River had intermediate characteristics between H. japonica and H. longispira and their populations are currently almost extinct.

Parasites and symbionts of freshwater mussels are poorly understood, although a diverse assemblage of mussel-associated leeches (Glossiphoniidae) was recently described. Here, we report on the discovery of a fish leech (Piscicolidae) in the mantle cavity of the freshwater mussel Cristaria plicata (Unionidae) in the Russian Far East. It is the first member of this leech family being associated with freshwater molluscs. This leech does not match any known genus and species both morphologically and genetically, and is described here as Alexandrobdella makhrovigen. & sp. nov. It uses mussels as shelter (and probably as a secondary host), while the Amur catfish Silurus asotus (Siluridae) seems to be the primary host. These novel findings indicate that mussel-associated leech assemblage contains at least one piscicolid species. Our fossil-calibrated phylogeny suggests that the crown group of Piscicolidae was originated in the Early Cretaceous. This primarily marine family shares at least five independent colonization events into freshwater environments.

The syntype of Pseudamnicola brachia (Westerlund, 1886), the only known Pseudamnicola sp. from Crete, is compared with a recently collected Pseudamnicola sp. which could be identified as a species new to science. Comparisons with data in the literature show us that P. brachia (Westerlund, 1886) has nothing in common with P. brachia sensu Schutt, 1980 as well as P. brachia sensu Szarowska et al ., 2015, but both are possibly conspecific with the new species which is described here. In addition we describe two new Bythinella spp. from Crete which could be found in addition to B. cretensis Schutt, 1980, and a new Valvata ( Tropidina ) sp. from Lake Kournas.

This is the first review of life cycles of trematodes with parthenitae and larvae in freshwater gastropods from forest biocoenoses of Ukrainian Polissia. Altogether 26 trematode species from 14 families were found circulating in 13 ways in molluscs from reservoirs connected with forest ecosystems of the region. Three-host life cycle is typical of 18 trematode species, two-host life cycle has found in 7 species, and four-host cycles has found in one species. Alaria alata Goeze, 1782, has three-host (Shults, 1972) and four-host cycles. Opisthioglyphe ranae (Froehlich, 1791) can change three-host life cycle to two-host cycle replacing the second intermediate host (Niewiadomska et al., 2006) with the definitive host. Species with primary two-host life cycle belong to Notocotylidae Lühe, 1909, Paramphistomidae Fischoeder, 1901 and Fasciolidae Railliet, 1758 families. Trematodes with three-host cycle have variable second intermediate hosts, including invertebrates and aquatic or amphibious vertebrates. Definitive hosts of trematodes are always vertebrates from different taxonomic groups. The greatest diversity of life cycles is typical for trematodes of birds. Trematodes in the forest biocoenoses of Ukrainian Polissia infect birds in six ways, mammals in three, amphibians in four, and reptiles in one way. The following species have epizootic significance: Liorchis scotiae (Willmott, 1950); Parafasciolopsis fasciolaemorpha Ejsmont, 1932; Notocotylus seineti Fuhrmann, 1919; Catatropis verrucosa (Frölich, 1789) Odhner, 1905; Cotylurus cornutus (Rudolphi, 1808); Echinostoma revolutum (Fröhlich, 1802) Dietz, 1909; Echinoparyphium aconiatum Dietz, 1909; Echinoparyphium recurvatum (Linstow, 1873); Hypoderaeum conoideum (Bloch, 1782) Dietz, 1909; Paracoenogonimus ovatus Kasturada, 1914; Alaria alata Goeze, 1782.

Echinostome metacercariae were investigated in freshwater snails from 26 districts in 7 provinces of upper northern Thailand. The species identification was carried out based on the morphologies of the metacercariae and adult flukes harvested from experimental hamsters, and on nucleotide sequences of internal transcribed spacer 2 (ITS2) and nicotinamide adenine dinucleotide dehydrogenase subunit 1 (nad1) genes. Twenty-four out of 26 districts were found to be infected with echinostome metacercariae in freshwater snails with the prevalence of 40.4%. The metacercariae were found in all 6 species of snails, including Filopaludina martensi martensi (21.9%), Filopaludina doliaris (50.8%), F. sumatrensis polygramma (61.3%), Bithynia siamensis siamensis (14.5%), Bithynia pulchella (38.0%), and Anenthome helena (4.9%). The echinostome metacercariae found in these snails were identified as Echinostoma revolutum (37-collar-spined) and Echinostoma macrorchis (45-collar-spined) morphologically and molecularly. The 2-week-old adult flukes of E. revolutum revealed unique features of the cirrus sac extending to middle of the ventral sucker and smooth testes. E. macrorchis adults revealed the cirrus sac close to the right lateral margin of the ventral sucker and 2 large and elliptical testes with slight indentations and pointed posterior end of the posterior testis. The ITS2 and nad1 sequences confirmed the species identification of E. revolutum, and the sequences of E. macrorchis have been deposited for the first time in Gen-Bank. The presence of the life cycle of E. macrorchis is a new record in Thailand and the snail F. doliaris as their second intermediate host seems to be new among the literature.

The Tonle Sap Lake in Cambodia is a crucial freshwater biodiversity hotspot and supports one of the world’s largest inland fisheries. Within the Tonle Sap basin, freshwater molluscs provide vital ecosystem services and are among the fauna targetted for commercial harvesting. Despite their importance, freshwater molluscs of the Tonle Sap basin remain poorly studied. The historical literature was reviewed and at least 153 species of freshwater molluscs have been previously recorded from throughout Cambodia, including 33 from the Tonle Sap basin. Surveys of the Tonle Sap Lake and surrounding watershed were also conducted and found 31 species, 15 bivalves (five families) and 16 gastropods (eight families), in the Tonle Sap basin, including three new records for Cambodia (Scaphula minuta, Novaculina siamensis, Wattebledia siamensis), the presence of globally invasive Pomacea maculata and potential pest species like Limnoperna fortunei. This study represents the most comprehensive documentation of freshwater molluscs of the Tonle Sap basin, and voucher specimens deposited at the Inland Fisheries Research and Development Institute, Cambodia, represent the first known reference collection of freshwater molluscs in the country. In order to combat the combined anthropogenic pressures, including invasive species, climate change and dams along the Mekong River, a multi-pronged approach is urgently required to study the biodiversity, ecology, ecosystem functioning of freshwater molluscs and other aquatic fauna in the Tonle Sap basin.

Digenetic trematode infections including schistosomiasis and fascioliasis have highly neglected statuses but are a menace to people in the poorest countries of the tropics, causing high morbidity and mortality in humans as well as great global losses in livestock production. This has neccesitated the widespread search for better control options for the snail vectors of these diseases. Hence, a novel drug - curcumin and nisin poly lactic acid (PLA) entrapped nanoparticles (CurNisNp) was screened for molluscicidal activity against the adults (> 2 months old) of Biomphalaria pfeifferi, Bulinus globosus and Lymnaea natalensis vector snails. Mortality was determined after 96-h of exposure at varying concentrations. The snails of the species L. natalensis were found to be the most susceptible to the molluscicide (LC50 323.6 ppm). This finding further supports the desirability of curcumin-nisin polylactic acid (PLA) nanoparticles as a molluscicide and therefore shows that it could be a good alternative to conventional molluscicides with prospects in the selective control of fascioliasis. However, more optimization of the drug could ensure a greater molluscicidal potency.

Background Schistosomiasis is a common parasitic disease designated as a neglected tropical disease by the World Health Organization. Schistosomiasis mansoni is a form of the disease that is caused by the digenean trematode Schistosoma mansoni, transmitted through Biomphalaria spp. as an intermediate host. Biomphalaria was introduced to Hong Kong, China in aquatic plants shipments coming from Brazil and the snail rapidly established its habitats in southern China. Earlier studies of Biomphalaria spp. introduced to southern China identified the snails as Biomphalaria straminea, one of the susceptible species implicated in S. mansoni transmission in South America. However, recent molecular investigations also indicated the presence of another South American species, B. kuhniana, which is refractory to infection. As such, it is important to identify accurately the species currently distributed in southern China, especially with emerging reports of active S. mansoni infections in Chinese workers returning from Africa. Methods We combined morphological and molecular taxonomy tools to precisely identify Biomphalaria spp. distributed in Guangdong Province, southern China. In order to clearly understand the molecular profile of the species, we constructed a phylogeny using mtDNA data (COI and 16S rRNA sequences) from six populations of Biomphalaria spp. from Shenzhen City in Guangdong Province. In addition, we examined the external morphology of the shell and internal anatomy of the reproductive organs. Results Both morphological and molecular evidences indicated a close affinity between Biomphalaria spp. populations from Guangdong and B. straminea from Brazil. The shell morphology was roughly identical in all the populations collected with rounded whorls on one side and subangulated on the other, a smooth periphery, an egg-shaped aperture bowed to one side, and a deep umbilicus. The shape and number of prostate diverticula (ranged from 11.67 to 17.67) in Guangdong populations supports its close affinity to B. straminea rather than B. kuhniana. Molecular analysis did not conflict with morphological analysis. Little genetic differentiation was observed within Biomphalaria populations collected. Phylogenetic analysis of COI and 16S rRNA haplotypes from snails collected and B. straminea sequences from Brazil and China using Bayesian inference revealed that Guangdong populations were clustered in one clade with B. straminea from Hong Kong of China and B. straminea from Brazil indicating their close affinity to each other. Conclusions Data obtained in the current study clearly show that the populations of Biomphalaria spp. investigated are B. straminea, and we assume that those snails were either introduced via passive dispersal from Hong Kong of China or as a result of multiple introduction routes from Brazil. Electronic supplementary material The online version of this article (10.1186/s40249-018-0505-5) contains supplementary material, which is available to authorized users.

Background Biomphalaria straminea is an invasive vector in China, posing a significant threat to public health. Understanding the factors affecting the establishment of this snail is crucial to improve our ability to manage its dispersal and potential risk of schistosomiasis transmission. This study sought to determine the spatial distribution of B. straminea in mainland China and whether environmental factors were divergent between places with and without B. straminea. Methods A malacological survey of B. straminea was conducted in Guangdong Province, China. Snails were identified using anatomical keys. Water and sediment samples were taken, and their physicochemical properties were analyzed using national standard methods. Landscape and climatic variables were also collected for each site. We compared the environmental characteristics between sites with and without B. straminea using Mann-Whitney U test. We further used generalized linear mixed models to account for seasonal effects. Results B. straminea was found at six sites, including one in Dongguan and five in Shenzhen. Probability map found a hot spot of B. straminea distribution at Shenzhen and Hong Kong. Sites occupied by B. straminea were characterized by higher median altitude, mean annual precipitation and moderate temperature. Water with snails had higher median concentrations of total nitrogen, nitrate and nitrites, ammoniacal nitrogen, calcium, zinc and manganese but lower dissolved oxygen and magnesium. Sediments with snails had higher median copper, zinc and manganese. B. straminea was associated with maximum temperature of the warmest month (pMCMC

The molluscan fauna of the Syoyakha (Zelenaya) River remain poorly explored even though the Syoyakha is one of the biggest rivers on the Yamal Peninsula. The Syoyakha River is remarkable for its high fish stocking capacity and it plays an important role in the seasonal distribution and migration of commercial fish species. Freshwater mollusks are known to be a major component of freshwater ecosystems and they make up a part of the diet of many commercially important fish species. The species composition of the mollusks inhabiting the lower reaches of the Syoyakha River has been studied. Five bivalve species of the family Sphaeriidae were found, namelySphaeriumcorneum(Linnaeus, 1758),Pisidiumcasertanum(Poli, 1791),P.globulare(Clessin in Westerlund, 1873),P.lilljeborgi(Clessin in Esmark et Hoyer, 1886) andP.dilatatum(Westerlund, 1897). In general, the molluscan fauna of the lower reaches of the Syoyakha River are taxonomically poor, which can be considered typical of freshwater invertebrate communities living at high latitudes. Another reason for the decline in species diversity may lie in the absence of any large transit watercourse in the basin in question allowing northward dispersion of the mollusks. The average density of mollusks in the watercourse stretch under study varied from 98.9 ind./m2to 620.5 ind./m2.P.globularesettlements had the highest recorded density of 1,442.9 ind./m2. The mollusks are confined to clayey, silty and sandy substrates with remnants of vegetation. The fauna is basically formed by widespread Palearctic and Holarctic mollusk species that have adapted to the extreme conditions of the Arctic. The findings may be used for hydrobiological and fishery characterization of the watercourse given that the recorded species ofS.corneum,P.globulare,P.lilljeborgi, andP.dilatatumare a major food item for important fish species, such as cisco, vendace, char, muksun, etc.

Information about rare species used for decide widely spectrum of problems. In practice ‒ for estimating environmental impact from human activities. For example by studying biodiversity in fundamental science. This information very important for monitoring and prevention of species extinction. Regional and Federal Red Books serve this aim. However freshwater mollusks species of the Bolshoy Yugan river basin not presented in the Federal Red Book of Russian Federation. In addition, in the Regional Red Books of Khanty-Mansi autonomous region and Tyumen region data about mollusks are absence. This paper the first step to fill in the gap. Article contains the first data about rare species of freshwater mollusks of the Bolshoy Yugan River basin collected during the field season of 2016. In future, these species possibly will be propose to inclusion in the Red Book of Khanty-Mansi autonomous region. I followed the standard techniques of mollusks sampling, fixation and laboratory treatment. In this research I call species rare if species occurrence was 5,0% and lower. I used contemporary macrosystems of mollusks in the level above family groups of both Bivalves and Gastropods. In addition, on the level under family groups and lower I used alternative approach, which consist of combination of two different taxonomic systems: “traditional” European and Ya.I. Starobogatov’s scientific school or “Russian”. The collection of mollusks is kept in the Federal Zapovednik (Nature Reserve) “Yuganskiy”, which was the material base of my study. In the article discussed aspects of rareness and difficulty of investigates freshwater mollusks. These difficulties connected with existence of different taxonomical approaches and underexplored mollusk's fauna and ecology. Studies of rare species in the Western Siberia are briefly considered. The results of own research and annotated list of rare mollusks species of Bolshoy Yugan River basin collected during the field season of 2016 are presented. Showed that significant part of species richness in the Bolshoy Yugan River basin consist of rare species. These results do not change independent of applied taxonomical approaches “traditional” or “Russian” and discussed with facts in malacologycal literature. There are 50 species of freshwater mollusks were find in 2016, 41 of them are rare in the Bolshoy Yugan River basin. In conclusion marked need for further research of freshwater mollusks. In addition denoted some important priorities of studies, such as systematics, fauna, zoogeography and ecology of mollusks. The question about inclusion in the Red Book of Khanty-Mansi autonomous region some any species of freshwater mollusks are still opened. Because needed additional facts about distribution and abundance species from others parts of region.Partial financial support for this study was obtained from the Ministry of Education and Science of Russian Federation (project 6.1352.2017/ПЧ).

Lake Lanao on Mindanao island is the largest freshwater lake in the Philippines and may represent one of the few ancient lakes in Southeast Asia. This lake’s fauna is best known for its endemic cyprinid fishes that have been nearly driven to extinction through various anthropogenic actions. In contrast, only little is known about Lake Lanao’s invertebrate fauna and its placement within related Southeast Asian taxa. We here focus on the diversity in freshwater molluscs, particularly the morphologically diverse viviparid gastropods, and provide first genetic insights into this group in order to test whether the morphological variability observed is also reflected by corresponding genetic variation. Mitochondrial sequence data indicate that these viviparids form a monophyletic group comprising morphologically distinct and partly genetically different (morpho)species. Both the high diversity found in cyprinid fishes and viviparid gastropods together with the geological and tectonic evolution of Mindanao suggest that Lake Lanao may have originated more than 100,000 years ago and is thus indeed an ancient lake. However, its fauna is under continuous threat not least from the introduction of non-native species, and the development and implementation of sustainable conservation strategies is direly needed.

In spite of considerable progress made in the prevention and control of schistosomiasis and other snail-borne diseases, transmission has intensified in some endemic areas as a result of land-use and climate changes. We used decision tree models and multivariate analysis to identify factors affecting the occurrence and abundance of medically important freshwater snail intermediate hosts in the Omo-Gibe river basin, Ethiopia. The models were based on a dataset of 140 samples collected from lakes, wetlands, rivers, dam reservoir shores and irrigation canals. A total of 1866 freshwater snails belonging to four genera and seven species were collected. Biomphalaria pfeifferi, Lymnaea natalensis and Bulinus globosus had fair to moderate predictive performance based on Kappa statistics (ĸ > 0.2), indicating that these species have clear environmental requirements within the habitat gradient studied. The most important variables influencing the abundance and occurrence of snail species were the presence of predator and competitor, canopy cover, type of water body, waste dumping and water pH. In conclusion, snail species occurred less frequently and in smaller numbers in water bodies with minimal human disturbances. Therefore, preventing human disturbance in water bodies may enhance aquatic biodiversity, thereby increasing the abundance of snail predators and competitors. Preventing the pollution of these ecosystems is essential to maintain their ecological integrity and sustain the ecosystem services they provide to local communities.

A new large population of the Asian clam Corbicula fluminea (O. F. Müller, 1774) was found within a reach (ca 210 km long) of one of the largest European rivers, the Vistula. The largest population and the largest individuals were found at the outlet of a channel collecting heated water from the cooling process at the Połaniec power station and adjacent parts of the river. In the northern part of the study area, bivalves occurred at the channel margins, in groyne fields, and in the shallows of sand banks or sandbars. The clams were less numerous in places where the river was regulated with straightened banks and stone ripraps. Twenty-five other taxa of mollusks were found altogether at the sampling stations where Corbicula was observed, including other non-indigenous mollusk species.

Bulinid snails act as intermediate host of schistosomes and the presence of the snail gives schistosomiasis an expansive characteristics. Schistosomiasis is of medical and veterinary importance in the tropical and subtropical regions. The shell shape and structure of radula teeth of bulinids are often specific to a species or genus, and are widely used for gastropod species identification. Bulinid species collected from schistosome endemic areas of Ogun State, South-western Nigeria were used for this study. Shell morphometrics were recorded using vernier caliper while the buccal mass of each snail was removed and permanent slides of the radulae were made according to standard procedure. There was a significant difference in the shell height, width, aperture height and aperture width between Bulinus globosus and Bulinus jousseaumei (p