Search

Morphological and molecular studies of the taxa of the Biomphalaria tenagophila complex were conducted on specimens from Argentina, Brazil, Paraguay, Peru, Uruguay and Venezuela. The morphological analysis included aspects of the shell, mantle, excretory organs and reproductive system. DNA barcode, ABGD and mPTP were used to group specimens into Operational Taxonomic Units (OTUs) and in attempt to solve species boundary delimitation problems within the Biomphalaria tenagophila complex. Population analyzes were also performed based on the cytochrome C oxidase I (COI) and 16S genes. The seminal vesicle, extension of the oviduct in relation to the distal ovispermioduct, vaginal pouch, aspect of the penial complex, aspect of the prepuce diaphragm, diaphragm papilla, extension of the penial sheath in relation to the prepuce and prepuce dimensions are essential for the determination of the taxa of the Biomphalaria tenagophila complex. An updated molecular phylogeny for Biomphalaria based on COI, 16S and ITS2 genes is presented and recover Biomphalaria tenagophila complex as monophyletic. The morphological, population and phylogenetic data observed in an integrated way define taxonomic questions, such as the proposition of a new status for B. guaibensis, which integrates into the Biomphalaria tenagophila complex. [ABSTRACT FROM AUTHOR]

Invasion of alien species is one of the major environmental problems in the globalised world. Therefore, identifying pathways for the introduction and spread of alien species can help to mitigate their impact on invaded ecosystems. This study focused on the freshwater snail Gyraulus chinensis, which invades Europe from eastern Eurasia, where it is native. It was first recorded in Europe about 50 years ago and has since expanded its distribution. However, its origin and the mechanisms of its spread have not yet been studied. Therefore, we performed molecular identification and estimated its origin and dispersal mechanisms based on a literature review, molecular phylogenetics, and population genetics. We found that the haplotypes of G. chinensis in Europe are closely related to southern East Asia, namely Hong Kong, Taiwan, and the Ryukyu Islands. The results also suggest multiple introductions, mainly due to the diversity of haplotypes detected in European G. chinensis populations. Currently, the distribution and invasion of the species in the outdoor environments are concentrated in southern Europe, probably due to thermal constraints. However, the species has been recorded in many indoor habitats in the northern part of Europe, indicating a high potential for its spread in the warmer world. [ABSTRACT FROM AUTHOR]

The freshwater gastropod fauna of Serbia can be considered understudied compared to the neighbouring countries. This is especially true for the species that frequently occur in smaller and transient habitats such as Aplexa hypnorum (Linnaeus, 1758), Physa fontinalis (Linnaeus, 1758), Anisus (Disculifer) vorticulus (Troschel, 1834), Hippeutis complanatus (Linnaeus, 1758) and Segmentina nitida (O.F. Müller, 1774). Our survey of various smaller habitats in the Pannonian part of Serbia took place in 2021 and 2022 and included 11 sites. One or more of the above-mentioned snail species were found at nine of these sites. Of particular interest are the findings of A. hypnorum, the species whose last and only confirmed finding dated back to the beginning of the 20th century. In total, we present three new localities of A. hypnorum and S. nitida. The number of known localities of A. vorticulus and H. complanatus has doubled (now seven and eight localities respectively). Physa fontinalis, a native species once quite common in the Pannonian areas, is with a declining frequency. During our survey, an abundant population of P. fontinalis was found at a new site. The results presented suggest that a comprehensive survey focusing on smaller and neglected habitats is necessary to fill the gaps in our knowledge of the occurrence and distribution of the freshwater gastropod fauna in Serbia. [ABSTRACT FROM AUTHOR]

Freshwater snails are commonly studied within the context of their role as intermediate hosts for digenetic trematodes. However, there are fundamental data deficiencies related to our understanding of directly transmitted parasites, such as coccidia, for freshwater snails. Because variation in coccidia pathogenicity and transmission among snail species likely has major impacts on snail community structure, we aimed to investigate the spatial distribution and prevalence of coccidia in several freshwater snail species throughout the Ozark and Ouachita Mountains ecoregions in Arkansas. We opportunistically collected 220 freshwater snails from 24 Ozark sites in summer 2022 and scanned fecal slides for the presence of coccidia. In summer 2023, we surveyed an additional 146 snails from 19 Ouachita sites. To test for apparent interactions among coccidia and trematodes, we scanned feces from a subset of snails (Physa and Planorbella in the Ozarks) that did not have concurrent trematode infections and from those that did. We observed oocysts that morphologically conformed to Pfeifferinella ellipsoides in 2 of the 9 snail taxa from 7 of the 43 sites. Planorbella trivolvis was infected at 2 of 6 sites in the Ozarks and 0 of 5 sites in the Ouachitas. Physa species were infected at 6 of 14 sites in the Ozarks and 0 of 12 sites in the Ouachitas. In the Ozarks, Pl. trivolvis had an overall prevalence of 0.13 (6 of 47), whereas individuals in the genus Physa had an overall prevalence of 0.08 (8 of 97). Our chi-square and Fisher exact tests revealed no significant evidence for trematode–coccidia competition or synergism within the two snail species. There were no other species infected, and we did not observe any coccidia in the snails from the Ouachitas. Our survey of 366 snails among 9 taxa and 43 sites represents the largest survey for freshwater snail coccidia to date and indicates that both Pl. trivolvis and Physa spp. may be primary hosts and/or reservoir hosts for Pf. ellipsoides in freshwater snail communities. The highly aggregated distribution of Pf. ellipsoides in northwestern Arkansas requires further investigation. Our results led to proposal of several hypotheses for additional research, including questions regarding the variation of coccidia host specificity and virulence. [ABSTRACT FROM AUTHOR]

The Great African Lakes in Uganda (Lake Albert and Lake Victoria) are known habitats to several sympatric species of Biomphalaria , intermediate snail hosts of the human parasite Schistosoma mansoni. However, accurate identification of snails by morphology alone can be problematic, highlighting a need for robust, on-site identification methods, since only certain species have important roles in parasite transmission. This study investigates the conchological variation within Biomphalaria species collected from these two Great East African Lakes. We compared the shell morphologies of Biomphalaria species using landmark-based morphometric techniques and were able to distinguish Biomphalaria species through canonical variate analysis (CVA) of the apical and apertural shell angles. After identification with molecular methods, three Biomphalaria species (B. pfeifferi , B. stanleyi , and B. sudanica), with heterogenous occurrences along the shoreline, were identified at Lake Albert that could be differentiated from one another using CVA of apical and apertural datasets; by contrast, a single Biomphalaria species was identified at Lake Victoria (B. choanomphala). When snails from both lakes were compared together, CVA was able to differentiate all four species using the apical dataset but not the apertural dataset. Of the Biomphalaria species identified, ecological phenotypic variation was only found in B. choanomphala , which exhibited two distinct ecological morphotypes. Furthermore, these two B. choanomphala morphotypes from Lake Victoria overlapped upon analysis of the apical dataset, yet were clearly separated upon analysis of the apertural dataset. Our study demonstrates that landmark-based morphometrics could play a future role in distinguishing sympatric Biomphalaria species in Uganda. [ABSTRACT FROM AUTHOR]

Long‐distance dispersal (LDD) is a critical process in the distribution of less‐migratory organisms. Migratory birds are considered the principal vector of LDD, especially over extremely long distances such as between continents. However, there has been no evidence of LDD spanning thousands of kilometers, even via birds. In this study, we collected a freshwater snail attached to a Latham's snipe. This snail was identified as the genus Glyptophysa through morphological and molecular identification based on four genetic regions. Considering the migration route of the bird and the distribution of the molluscan genus, we conclude that the snail was attached to a bird which migrated over 4000 km across the ocean. This finding demonstrates the LDD on an intercontinental scale of an organism via a migratory bird, which many biologists have long presumed to occur. [ABSTRACT FROM AUTHOR]

We present a genome assembly from an individual Anisus vortex (the Whirlpool Ramshorn snail; Mollusca; Gastropoda; Hygrophila; Lymnaeoidea; Planorbidae). The genome sequence is 869.5 megabases in span. Most of the assembly is scaffolded into 18 chromosomal pseudomolecules. The mitochondrial genome has also been assembled and is 13.57 kilobases in length.

El molusco exótico Helisoma duryi es un popular caracol ornamental de agua dulce que se utiliza para controlar las microalgas en los acuarios. Ahora se presenta como una especie introducida en hábitats acuáticos de Europa, África y América del Sur. Presentamos el primer hallazgo de una población aclimatada de H. duryi en Marruecos y el norte de África. A pesar de ubicarse en una única localidad de las más de 100 muestreadas por nosotros, las investigaciones en curso podrían revelar pronto más citas de la especie en el país y el resto del continente. Se deben establecer políticas y procedimientos estrictos de aplicación de la ley en el comercio de especies acuáticas como medida preventiva para preservar la biodiversidad nativa.

Dispersal is a fundamental mechanism for maintaining biodiversity, and long‐distance dispersal (LDD) has attracted the interest of many researchers owing to its unusual characteristics. Conventionally, LDD has been defined based on absolute and proportional distances; however, it has recently been redefined based on geographic and genetic limits. Based on this redefinition, short‐distance dispersal can have the same characteristics as LDD, depending upon the dispersal dynamics of an organism. However, the effects of LDD at a local scale on the genetic structure and diversification of organisms are poorly understood, since many studies have focused on definitive LDD, such as oversea dispersal.We focused on the freshwater snail Gyraulus sp. on an oceanic island, Chichijima Island, attempting to clarify the dynamics and effects of LDD on its genetic structure. We conducted molecular phylogenetic analyses, including divergence‐time estimation, using mitochondrial DNA and nuclear DNA markers to reveal the origin of the snail. In addition, we clarified the genetic structure, gene flow, and evolutionary history of snails on the island using mitochondrial DNA and genome‐wide single‐nucleotide polymorphisms. Finally, we followed a landscape ecology approach to identify barriers to dispersal.Our phylogenies suggested that the snail has a single origin. Based on our divergence–time estimation, colonisation was estimated to have occurred around the late Pliocene to early Pleistocene. Our population genetic analyses documented genetic differentiation even within this small oceanic island. Based on the divergence time estimation and approximate Bayesian computation using single‐nucleotide polymorphisms, the differentiation was estimated to have begun around the late Pleistocene. Little gene flow occurred between the geographically structured snail genetic groups. Landscape analysis suggested that catchment boundaries were a major barrier to dispersal.Considering the geography of the island, these results suggested that low‐frequency dispersal over barriers is an important factor in genetic differentiation within the island. Furthermore, dispersal over barrier may be considered LDD, even though the dispersal distance is only several kilometres.Genetic evidence also suggested that resistance to gene flow over the barrier, rather than distance, is more important in determining whether dispersal should be considered LDD. This suggests that a definition of LDD that depends only on the distance may mislead an understanding of dispersal mode. [ABSTRACT FROM AUTHOR]

Gastropoda are an important component of the freshwater benthic communities of Western Siberia and participate in a number of trophic relationships and as the intermediate hosts of trematodes. The purpose of this study is defining the ratio of Bithyniidae mollusks between other gastropods with regard to species diversity, and to compile all information about the abundance of bithyniid snails that we examined over 27 years in four major basins situated in the Novosibirsk region. Analyzing the data diversity and abundance of gastropod communities from freshwater ecosystems south of Western Siberia, we found that 22% of the water bodies contained bithyniid snails. In total, 201 samples that were abundant with bithyniid snails of reproductive age were collected in 34 localities in 25 water bodies. While these freshwater snails are not abundant in most of the inspected reservoirs (fewer than 10 mollusks per square meter), two of the water bodies accommodated a great number of Bithyniidae (more than 100 ind.·m−2). Bithyniid snail abundance may vary tenfold in different years in the same water body. This and the study of seasonal dynamics show that the abundance of bithyniid snails of reproductive age decreased from June to August in all years. The results of this study can be used to identify and predict the natural foci of opisthorchiasis in the south of Western Siberia. [ABSTRACT FROM AUTHOR]

The file ramshorn snail Planorbella pilsbryi Baker, 1926 (Gastropoda: Hygrophila: Planorbidae) is a widespread herbivorous North American freshwater snail found in diverse habitats, including standing and moving water bodies. Genome skimming by Illumina sequencing allowed the assembly of a complete nuclear rRNA repeat sequence and a complete circular mitogenome of 13,720 bp from P. pilsbryi consisting of 75.3% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the typical order found in panpulmonate snails. Planorbella pilsbryi COXI features a rare TTG start codon while COXII, CYTB, ND2, ND3, and ND5 exhibit incomplete stop codons completed by the addition of 3′ A residues to the mRNA. Phylogenetic reconstruction of mitochondrial protein-coding gene and rRNA sequences places P. pilsbryi as sister taxon to Planorbella duryi (Planorbidae) within family Planorbidae, which is consistent with previous phylogenetic hypotheses.

Copyright of Egyptian Journal of Experimental Biology (Zoology) is the property of Egyptian Society of Experimental Biology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

The family Planorbidae comprises freshwater gastropods with planispiral, spiral and limpet-shaped shells. Subfamily Planorbinae sensu stricto, has a richness of almost 300 species, with some of the main genera being Biomphalaria Preston, 1910 and Drepanotrema Fischer & Crosse, 1880. Some Biomphalaria species are of concern to human health as they are intermediate hosts of blood flukes in Latin America. In Argentina, the family Planorbidae is represented by 15 species in four genera. In Northern Argentina (NOA region), records of the family are scarce, and most of them are a result of occasional collecting. We provide an updated checklist of Planorbinae in NOA resulting from fieldwork, material in malacological collections, and data in the literature. Nine species occur in the area: four species of Biomphalaria and five of Drepanotrema. Among Biomphalaria species, we recorded Biomphalaria straminea (Dunker, 1848), which is considered a natural host of the blood fluke Schistostoma mansoni Sambon, 1907, for first time in Salta province; the known geographic distribution of B. straminea is extended in the country. [ABSTRACT FROM AUTHOR]

Freshwater mollusc species were collected in Bulgaria (2007, Varna Region) and Greece (2013, Corfu Island) by one of the present authors (MLZ). Within this material, five new species were detected and described in the present article: Bithynia beloslavensis n. sp. from Bulgaria and Bithynia corfuensis n. sp., Pseudobithynia nigra n. sp., Gyraulus messonghi n. sp. and Pseudamnicola kavosensis n. sp. from Corfu Island, Greece. The descriptions are illustrated with photos of the holotypes and details of the penis morphology. [ABSTRACT FROM AUTHOR]

Abstract Background Islands have traditionally been the centre of evolutionary biological research, but the dynamics of immigration and differentiation at continental islands have not been well studied. Therefore, we focused on the Japanese archipelago, the continental islands located at the eastern end of the Eurasian continent. While the Japanese archipelago is characterised by high biodiversity and rich freshwater habitats, the origin and formation mechanisms of its freshwater organisms are not clear. In order to clarify the history of the planorbid gastropod fauna, we conducted phylogenetic analysis, divergence time estimation, ancestral state reconstruction, and lineage diversity estimations. Results Our analyses revealed the formation process of the planorbid fauna in the Japanese archipelago. Most lineages in the Japanese archipelago have closely related lineages on the continent, and the divergence within the Japanese lineages presumably occurred after the late Pliocene. In addition, each lineage is characterised by different phylogeographical patterns, suggesting that immigration routes from the continent to the Japanese archipelago differ among lineages. Furthermore, a regional lineage diversity plot showed that the present diversity in the Japanese archipelago potentially reflects the differentiation of lineages within the islands after the development of the Japanese archipelago. Conclusions Although additional taxon sampling and genetic analysis focused on each lineage are needed, our results suggest that immigration from multiple routes just prior to the development of the Japanese archipelago and subsequent diversification within the islands are major causes of the present-day diversity of the Japanese planorbid fauna.

The set of ancient lakes on Sulawesi, Indonesia, represents a unique global hotspot of aquatic biodiversity. These lakes have been recognized widely because of their high number of endemic species with specialized and distinctive morphological characters, life history and ecological adaptations. An interesting case of unusual life history involving brood care exists in the planorbid limpets of the genus Protancylus , which live exclusively as epizoans on the endemic pachychilid gastropod Tylomelania. We aimed to unravel the evolutionary and phylogeographical patterns of Protancylus from the Malili lakes and Lake Poso using two mitochondrial markers in an integrated framework that includes morphological, life-history and ecological data. At least three species of Protancylus evolved allopatrically, with a newly recognized species occurring in lakes Matano and Mahalona. All species are characterized by low morphological variation, shared life-history traits including a unique reproduction strategy. Our genetic data indicates that a drift-based geographic speciation mode correlates with the present distribution pattern. The initial diversification significantly predates the ages of the respective lakes and the lineages of Protancylus are significantly older than their corresponding Tylomelania 'hosts'. The deep split between P. pileolus of Lake Poso and the populations in the Malili lakes is remarkable and hints to a very early separation in a time frame when Sulawesi reached its current composition. As colonization and onset of diversification is strikingly different in Tylomelania and the epizoic Protancylus , co-evolutionary components in this association can be excluded and both evolved largely independently. We discuss and compare our findings to other invertebrate assemblages in the ancient lakes of Sulawesi. [ABSTRACT FROM AUTHOR]

Trematode-induced castration of snails is widespread and can lead to other life history changes of snails such as changes in trajectories of size and growth or survival. The changes produced likely depend on whether the parasite or host controls allocation of host resources remaining after partial or complete cessation of host current reproduction by castrating trematodes. Documenting host life history changes, like changes in host size in response to castration, is a first step in assessing whether these changes are beneficial to the parasite (increasing transmission success) or to the host (outliving the infection) or to neither. Herein, we test for differences in size and survival among individuals of two snail species in relation to infection by Echinostoma spp. trematodes. Active shedding of Echinostoma spp. was associated with castration of all Stagnicola elodes snails from a site in Eastern Ontario. Snails actively shedding cercariae were not different in size from non-shedding, egg-laying snails but had a higher mortality than egg-laying snails. Active shedding of Echinostoma spp. cercariae was also associated with castration of nearly all Helisoma trivolvis monitored, from a site in Southwestern Ontario. Actively shedding, non-laying H. trivolvis hosts were smaller on average than non-shedding egg-laying hosts, but both non-laying and egg-laying snails survived equally well. We discuss these results in light of what is known about effects of castration on snail hosts in terms of growth and survival for these and other trematode species and speculate on whether changes in size or survival benefits parasite or host. [ABSTRACT FROM AUTHOR]

The construction of Lake Kariba brought about a rise in the incidence of schistosomiasis in its surrounding towns of Kariba (Zimbabwe) and Siavonga (Zambia). After extensive control programs in Kariba, schistosomiasis prevalence dropped significantly. The objective of this study was to revisit the same localities sampled by Chimbari et al. (2003), and provide an update on the snail community and prevalence of trematodes in the Northern shore of Lake Kariba while focusing on planorbid species. Monthly sampling of snails at 16 sites along the Northern shoreline of Lake Kariba, near Kariba town, was undertaken for one year. Minimum one specimen per morphotype was identified using molecular barcoding (sequencing a fragment of cytochrome c oxidase I subunit (COI)). The infection status of snails was assessed by Rapid Diagnostic PCRs (RD-PCR), and trematode infections were genotyped by sequencing COI and 18S rDNA markers. We collected and identified seven snail species: Bulinus truncatus, Bulinus forskalii, Gyraulus sp., Physella acuta, Bellamya sp. , Radix affinis plicatula and Pseudosuccinea columella. Physella acuta was the most abundant snail species (comprising 56.95% of the total snail count) and present at all sites. The B. truncatus population was found to be infected with the stomach fluke Carmyerius cruciformis , a Petasiger sp. and a trematode species belonging to the family Notocotylidae. No Schistosoma sp. infections were detected in our collected snail specimens. We report B. truncatus as an intermediate snail host for Carmyerius cruciformis , and the presence of three non-schistosome trematode species that have not been reported in Lake Kariba before. Furthermore, we detect a possible shift in the snail community when compared to the report by Chimbari et al. (2003): this is the first record of Gyraulus sp. in Lake Kariba, and we did not observe the previously reported B. pfeifferi , B. globosus and Radix natalensis. Although this shift in snail communities might have contributed to the absence of Schistosoma spp. detection in this study, further monitoring of final and intermediate hosts across the Kariba basin is essential to prove a decrease of schistosomiasis in the area. [Display omitted] [ABSTRACT FROM AUTHOR]

The file ramshorn snail Planorbella pilsbryi Baker, 1926 (Gastropoda: Hygrophila: Planorbidae) is a widespread herbivorous North American freshwater snail found in diverse habitats, including standing and moving water bodies. Genome skimming by Illumina sequencing allowed the assembly of a complete nuclear rRNA repeat sequence and a complete circular mitogenome of 13,720 bp from P. pilsbryi consisting of 75.3% AT nucleotides, 22 tRNAs, 13 protein-coding genes, 2 rRNAs and a control region in the typical order found in panpulmonate snails. Planorbella pilsbryi COXI features a rare TTG start codon while COXII, CYTB, ND2, ND3, and ND5 exhibit incomplete stop codons completed by the addition of 3′ A residues to the mRNA. Phylogenetic reconstruction of mitochondrial protein-coding gene and rRNA sequences places P. pilsbryi as sister taxon to Planorbella duryi (Planorbidae) within family Planorbidae, which is consistent with previous phylogenetic hypotheses. [ABSTRACT FROM AUTHOR]

The pronounced dry season determines the characteristics of the semiarid region of Brazil. Numerous small reservoirs are built to overcome this condition, accumulating multiple uses and causing important changes in the landscape and the local biota. Considering the limited amount of information about the malacofauna of reservoirs, mainly in the Northeast region of the country, this inventory provides a list of mollusks from three important reservoirs located in the city of São Julião, state of Piauí. The collections were carried out monthly between May/2017 and April/2018, sampling a total of 11,149 mollusks, corresponding to the species Melanoides tuberculata (Müller, 1774) (n = 9,724), Biomphalaria straminea (Dunker, 1848) (n = 1,361) and Pomacea lineata (Spix, 1827) (n = 64). The richness of mollusks from the three reservoirs was low, similar to those described in studies conducted in other regions of Northeast Brazil. There was a significant difference in the abundance of M. tuberculata and B. straminea among the studied reservoirs. These environments are not connected and are installed in urban and rural areas, presenting different ecological conditions. The relationship between the human population and the reservoirs, associated with the lack of sanitation, increases the risks of spreading waterborne diseases besides the development of environmental imbalance by the introduction of exotic species. [ABSTRACT FROM AUTHOR]

Two new locations in Spain of Bulinus truncatus (Audouin, 1827) (Gastropoda, Planorbidae), intermediate host of urinary Schistosomiasis Two new populations of the planorbid snail species Bulinus truncatus were found in Spain in 2014. The first consisted of shells only, found in the lagoon of Villena (province of Alicante), which had dried up at the beginning of the 19th century. This finding is of important biogeographic interest because it links the presence of this species in northern Catalonia with its detection in southern Andalucia as this species had not been found previously in the regions of Murcia or Valencia. The second population was found in El Ejido (province of Almeria), and thousands of living specimens were found here. This allowed a complete shell characterisation and molecular assessment by means of sequencing the cox1 gene of the mitochondrial DNA genome, which showed 100% homology with sequences of other populations of the same snail species available in the GenBank. The finding of B. truncatus in Almeria is of additional value given the applied importance of this planorbid species as a vector of urinary Schistosomiasis, thus representing a risk of introduction and autochthonous transmission of the disease in Spain, as has occurred in other southern European countries in the past and recently.

Durante 2014, los autores han hallado dos nuevas poblaciones de Bulinus truncatus en España. En una de ellas, la laguna de Villena (Alicante), que fue desecada a principios del siglo XIX, sólo se encontraron conchas, mientras que en la otra, que se encuentra en El Ejido (Almería), se hallaron miles de ejemplares vivos. El enclave de Villena tiene un gran interés biogeográfico pues enlaza las poblaciones catalanas con las andaluzas, ya que ni en Murcia ni hasta ahora en la Comunidad Valenciana se conocía su presencia. La población almeriense ha sido objeto de estudio conquiliológico y molecular (gen cox1 del ADN mitocondrial) detectándose un 100% de homología con otras poblaciones de B. truncatus cuyas secuencias ya están disponibles en el GenBank. El hallazgo almeriense es de gran interés por la posible llegada a España de la Schistosomiasis urinaria y establecerse una transmisión autóctona, como ha ocurrido ya en otros países europeos en el pasado y recientemente.

A new species of the family Planorbidae is described from the land thermal spring Khakusy, on the northeastern shore of Lake Baikal. The description of Gyraulus takhteevi sp. n. includes morphological characters and gene sequences (COI of mtDNA) for the species separation from sister taxon Gyraulus acronicus (A. Férussac, 1807) collected from the small Krestovka River in-flowing into the south-western part of the Lake. The new species differs from G. acronicus in small shell size of adults, having smaller number of prostate folds (maximal up to 26 in G. takhteevi n. sp. vs. 40 in G. acronicus), a short preputium (approximately twice shorter than the phallotheca), and an elongated bursa copulatrix. The population of Gyraulus takhteevi sp. n. consists of two co-existent morphs: one of them has a narrow shell spire and the second is characterized by wide spire similar to the shell of G. acronicus. One of the two revealed haplotypes of the new species includes both morphs, while the second consists of snails with wide spired shells. [ABSTRACT FROM AUTHOR]

The study was carried out to understand the factors that affect community structure and generate heterogeneity in gastropod species diversity in various types of man-made ponds (e.g., subsidence ponds, sand pits and fish ponds at forested and non-forested locations). The studied waterbodies differed in water chemistry, bottom sediment type, source and drainage of water and in terms of snail occurrence patterns. Differences in gastropod species composition were related to differences in bottom sediments and water chemistry. Two-way indicator species analysis split the clusters into four groups with respect to substratum type and location. Forest ponds were important for the gastropod diversity and specifically for Planorbidae species. [ABSTRACT FROM AUTHOR]

Schistosomiasis remains a major parasitic disease, endemic in large parts of South America. Five neotropical species of Biomphalaria have been found to act as intermediate hosts of Schistosoma mansoni in natural populations, while others have been shown to be susceptible in experimental infections, although not found infected in the field. Among these potential intermediate hosts, Biomphalaria peregrina represents the most widespread species in South America, with confirmed occurrence records from Venezuela to northern Patagonia. In this study, we report the southernmost record for the species at the Pinturas River, in southern Patagonia, which finding implies a southward reassessment of the limit for the known species of this genus. The identities of the individuals from this population were confirmed through morphological examination, and by means of two mitochondrial genes, cytochrome oxidase subunit I (COI) and 16S-rRNA. With both markers, phylogenetic analyses were conducted in order to compare the genetic background of individuals from the Pinturas River with previously genetically characterized strains of B. peregrina from various South-American locations. In addition, we produced a potential distribution model of B. peregrina in South America and identified the environmental variables that best predict that distribution. The model was estimated through a maximum entropy algorithm and run with occurrence points obtained from several sources, including the scientific literature and international databases, along with climatic and hydrographic variables. Different phylogenetic analyses with either the COI or 16S-rRNA sequences did not conflict, but rather gave very similar topological organizations. Two major groups were identified, with sequences from the Pinturas River grouping together with haplotypes from subtropical and temperate regions. The model developed had a satisfactory performance for the study area. We observed that the areas with higher habitat suitability were found to be mainly linked to subtropical and temperate regions of South America between 15° and 45° south latitude, with different moderate- and low-suitability areas outside this range. We also identified the coldest temperatures as the main predictors of the potential distribution of this snail. Susceptibility surveys would be required to evaluate if southern populations of B. peregrina still retain their potential as intermediate hosts of S. mansoni.

The complete mitochondrial genome of a freshwater planorbid snail, Planorbella duryi (Mollusca, Gastropoda) was recovered from de novo assembly of genomic sequences generated with the Illumina NextSeq500 platform. The P. duryi mitogenome (14,217 base pairs) is AT rich (72.69%) and comprises 13 protein-coding genes, two ribosomal subunit genes, and 22 transfer RNAs. The gene order is identical to that of Biomphalaria glabrata and other snail species in the family Planorbidae. This is the first full characterization of a mitochondrial genome of the genus Planorbella.

In contrast to the well-studied trematode fauna of lymnaeid snails, only little is known about the role of small planorbid snails as first intermediate hosts for trematodes in temperate freshwater systems. This study aims at closing this gap by assessing the diversity and composition of larval trematode communities in Gyraulus albus and Segmentina nitida in a Central European reservoir system, and by providing an updated comprehensive review of the published trematode records of these snail hosts. A total of 3691 planorbid snails (3270 G. albus; 421 S. nitida) was collected in three consecutive years from four reservoirs of the River Ruhr catchment area in Germany. Gyraulus albus showed a higher overall trematode prevalence (11.7%) and more diverse trematode fauna (12 species) compared to S. nitida, which harboured three species and showed a lower trematode prevalence (1.7%). Altogether, 13 trematode species belonging to four families were identified in both hosts. Seven trematode species encountered in this study represent novel records for these hosts, and/or constitute first records of these larval stages from Germany. Trematode component communities in G. albus were stable across seasons and years, indicating excellent conditions for trematodes in this snail host and the continuous presence of the final hosts of the most dominant trematode species. Overall, this study reveals the importance of small planorbid snails, in particular G. albus, as first intermediate hosts for a species-rich trematode fauna in European freshwater systems, and highlights the parasites' contribution to the ecosystem's biodiversity. [ABSTRACT FROM AUTHOR]

New larval avian schistosomes found in planorbid snails from Brazil and USA were used for morphological and molecular studies. Eggs with a distinctive long polar filament were found in ducks infected experimentally with Brazilian cercariae. Similar eggs were reported previously in wild or experimentally infected anatids from Brazil, South Africa, and the Czech Republic. Molecular phylogenetic analyses showed that the North American and European schistosomes are sister taxa, which are both sister to the Brazilian species. However, these clades do not group with any named genus. Molecular data plus egg morphology suggest that these are new putative genera and species of avian schistosomes that can cause human cercarial dermatitis in the Americas, Africa and Europe. [ABSTRACT FROM AUTHOR]

We report digeneans (Diplostomidae, Crassiphialinae) in the endangered freshwater fishes Valencia letourneuxi and Valencia robertae, endemics of Western Greece. Digenean metacercariae occurred in two forms in the abdominal cavity, excysted and encysted, the latter attached to the gonads, liver and alimentary tract. Parasites were, using morphological and molecular techniques, identified as two representatives of Crassiphialinae, specifically part of the Posthodiplostomum- Ornithodiplostomum clade. The spatial, seasonal, and age class variation in parasite prevalence was examined. Autumn parasite prevalence varied between the six populations sampled (18.2 to 100%). Seasonal prevalence at the two sites sampled quadannually peaked in autumn and reached its lowest value in spring; prevalence increased with size to 100% in young adult fish. We did not find a correlation between prevalence and host sex. Overall parasites' weight averaged 0.64% of the host's, while parasite weight increased with host weight. A comparison of relative condition and hepatosomatic and gonadosomatic indices of infected and metacercariae-free specimens showed that infection did not have a significant effect on host body condition and reproduction. Regarding the parasite's life cycle, planorbid gastropods are proposed as potential first intermediate hosts in view of the host's diet and occurrence data of molluscs in the ecosystem. This is the first record of a diplostomid digenean in valenciid fishes and of representatives of the Posthodiplostomum- Ornithodiplostomum clade in a native Greek freshwater fish. Our findings are discussed in conjunction to fish conservation interventions, since parasites may contribute to the decline of endangered species. [ABSTRACT FROM AUTHOR]

Research on behavioural fever in Planorbarius corneus was undertaken using a longitudinal thermal gradient. Before the experiment, snails were acclimated at 19 °C. Following injections of lipopolysaccharide (LPS, a pyrogenic agent), ketoprofen (an antipyretic) or saline solution (control), thermal behaviour of the animals was automatically recorded for 48 h. The results demonstrated that LPS-induced symptoms of behavioural fever were inhibited by ketoprofen. Additionally, it was observed that snails which, before the injection of LPS, were preinjected with ketoprofen showed symptoms of behavioural fever with a 20-h delay. This result shows the inhibitory effect of ketoprofen on the occurrence of behavioural fever symptoms in P. corneus. It may suggest some similarity in mechanism of enhanced thermal preference in snails to vertebrate fever--both effectively inhibited by aspirin-like anti-inflammatory compounds. [ABSTRACT FROM AUTHOR]

Many chemicals are applied for disinfecting purposes. Although chlorination is the most common procedure, it has many drawbacks. So there becomes an urgent need for new chemicals which are both effective and less harmful to other water fauna. The present work aims at investigating the comparative effects of chlorine and Huwa-san as a new disinfectant on Biomphalaria alexandrina snails which act as bioindicators of toxicity, besides evaluating their miracicidal and cercaricidal activities. The results showed that Huwa-san was more toxic on tested snails than chlorine, where the LC values were 21 and 1368.9 ppm, respectively after 24 h. Also, it was found that the activities of catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and glutathione peroxidase (GPX) in snails' tissues were either induced or inhibited according to the tested disinfectant. Regarding reduced glutathione (GSH) content, it was increased as chlorine concentrations increased, while it reached its minimum content at the highest Huwa-san concentration. Such fluctuations were supported by histopathological examination of digestive and hermaphrodite glands, as prolonged exposure to chlorine led to more detrimental effects than Huwa-san concentrations. Moreover, Huwa-san was more effective on Schistosoma mansoni miracidia than on its cercariae, while the reverse was observed with chlorine. In conclusion, Huwa-san as a newly applied disinfectant can also be used as miracicidal and cercaricidal agent at small concentrations. Despite being more toxic to B. alexandrina snails, the chronic effect of its sublethal concentrations is less harmful than chlorine. [ABSTRACT FROM AUTHOR]

The aquatic planorbid snail Biomphalaria glabrata is one of the most intensively-studied mollusks due to its role in the transmission of schistosomiasis. Its 916 Mb genome has recently been sequenced and annotated, but it remains poorly assembled. Here, we used targeted capture markers to map over 10,000 B. glabrata scaffolds in a linkage cross of 94 F1 offspring, generating 24 linkage groups (LGs). We added additional scaffolds to these LGs based on linkage disequilibrium (LD) analysis of targeted capture and whole-genome sequences of 96 unrelated snails. Our final linkage map consists of 18,613 scaffolds comprising 515 Mb, representing 56% of the genome and 75% of genic and nonrepetitive regions. There are 18 large (> 10 Mb) LGs, likely representing the expected 18 haploid chromosomes, and > 50% of the genome has been assigned to LGs of at least 17 Mb. Comparisons with other gastropod genomes reveal patterns of synteny and chromosomal rearrangements. Linkage relationships of key immune-relevant genes may help clarify snail-schistosome interactions. By focusing on linkage among genic and nonrepetitive regions, we have generated a useful resource for associating snail phenotypes with causal genes, even in the absence of a complete genome assembly. A similar approach could potentially improve numerous poorly-assembled genomes in other taxa. This map will facilitate future work on this host of a serious human parasite. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The effects of sub-lethal concentrations of bisphenol A on some biochemical parameters inBiomphalariaalexandrinasnail's hemolymph and tissues as well as on histological changes of the hermaphrodite gland were evaluated. Adult snails were exposed to sub-lethal concentrations for four weeks and samples of snails were investigated after two and four weeks. Total protein and albumin levels in hemolymph, as well as lipid peroxidation and glutathione contents of snails’ tissues, were measured. After two weeks of exposure, total protein content and albumin levels decreased in all groups. Elevation of lipid peroxidation levels was correlated with decreasing glutathione content in the treated snails. Histological examination of the hermaphrodite gland revealed deformations in eggs and affected sperm production. [ABSTRACT FROM PUBLISHER]

En Chile la familia Planorbidae está representada por el género Biomphalaria Preston, 1910, compuesta por siete especies distribuidas desde Isluga hasta el río Puelo. De estas especies, solo B.peregrina, ampliamente distribuida en el neotrópico, y Biomphalaria aymara de Isluga, han sido reconocidas sobre la base de la morfología del sistema reproductor y la rádula, caracteres que fueron utilizados en el presente estudio para diferenciar a Biomphalaria cristiani como nueva especie del grupo y primer registro de la familia en la Patagonia chilena, ampliando su actual rango de distribución. Los caracteres que permiten la diagnosis de B. cristiani son el saco vaginal vestigial truncado, ausencia del desarrollo de los músculos suspensores del pene, vaina del pene corta en relación al prepucio, oviducto largo en relación al espermioducto y vaso deferente más delgado y largo que la vaina del pene, de tamano similar al prepucio. La localidad tipo de Biomphalaria cristiani sp. nov. es Laguna Cisnes (47°7'10.02"S, 72°27'40.65"W), región de Aysén.The family Planorbidae in Chile is represented by the genus Biomphalaria Preston, 1910, consisting of seven species distributed from Isluga to Puelo River. Of these species, only Biomphalaria peregrina widely distributed in the neotropical and Biomphalaria aymara from Isluga are recognized based on the morphology of the reproductive system and radula, characters that were used in the following study to differentiate Biomphalaria cristiani as a new species of this group and first record of the family in Chilean Patagonia, extending its current distribution range. The characters for the diagnosis of B. cristiani are: truncated vestigial vaginal pouch, lack of development of the penis retractor muscles, penis sheath shorter than the prepuce, oviduct longer than the spermiduct and vas deferens thinner and longer than the penis sheath, similar size to the prepuce. The type locality of B. cristiani nov. sp. is Laguna Cisnes (47°7'10.02"S; 72°27'40.65"W), Aysén region.

The transmission of some schistosome parasites is dependent on the planorbid snail hosts. Bulinus truncatus is important in urinary schistosomiasis epidemiology in Africa. Hence, there is a need to define the snails’ phylogeography. This study assessed the population genetic structure of B. truncatus from Giza and Sharkia (Egypt), Barakat (Sudan) and Madziwa, Shamva District (Zimbabwe) using mitochondrial cytochrome oxidase subunit 1 gene (COI) and internal transcribed spacer 1 (ITS 1) markers. COI was sequenced from 94 B. truncatus samples including 38 (Egypt), 36 (Sudan) and 20 (Zimbabwe). However, only 51 ITS 1 sequences were identified from Egypt (28) and Sudan (23) (because of failure in either amplification or sequencing). The unique COI haplotypes of B. truncatus sequences observed were 6, 11, and 6 for Egypt, Sudan, and Zimbabwe, respectively. Also, 3 and 2 unique ITS 1 haplotypes were observed in sequences from Egypt and Sudan respectively. Mitochondrial DNA sequences from Sudan and Zimbabwe indicated high haplotype diversity with 0.768 and 0.784, respectively, while relatively low haplotype diversity was also observed for sequences from Egypt (0.334). The location of populations from Egypt and Sudan on the B. truncatus clade agrees with the location of both countries geographically. The clustering of the Zimbabwe sequences on different locations on the clade can be attributed to individuals with different genotypes within the population. No significant variation was observed within B. truncatus populations from Egypt and Sudan as indicated by the ITS 1 tree. This study investigated the genetic diversity of B. truncatus from Giza and Sharkia (Egypt), Barakat area (Sudan), and Madziwa (Zimbabwe), which is necessary for snail host surveillance in the study areas and also provided genomic data of this important snail species from the sampled countries.