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Amik Lake or, historically, Lake of Antioch, was a large freshwater body in the lower Orontes River basin (Hatay Province, Turkey) that was drained in the 1940s–1970s. Several endemic animal species were described from this lake, including the freshwater mussel Anodonta pseudodopsis Locard, 1883 (Bivalvia: Unionidae) characterized by a large rounded shell covered by a peculiar yellow or yellowish-brown periostracum. Molecular analyses of topotypes of this nominal taxon collected from the former lake's tributaries in the Amik Plain indicate that it is an intra-specific lineage of the widespread Anodonta anatina (Linnaeus, 1758) based on the mitochondrial COI and 16S rRNA , and the nuclear 28S rRNA gene fragments. Geometric morphometric analyses using the lectotype and topotypes of Anodonta pseudodopsis support our DNA-based hypothesis on the status of this nominal taxon. A new synonymy is provided as follows: Anodonta anatina = Anodonta pseudodopsis syn. nov. The syntype of Anodonta pseudodopsis SMF 5129 "See von Antiochia" (Senckenberg Research Institute and Natural History Museum, Frankfurt, Germany) is designated here to be the lectotype of this nominal taxon. Finally, we conclude that Anodonta anatina range covers the Orontes River basin in Turkey and Syria and the Nahr al-Kabir al-Shamali River in the Latakia Governorate of Syria. This intraspecific lineage of Anodonta anatina and other freshwater mussels of the Middle East are highly threatened due to multiple anthropogenic impacts and must be a focus of international conservation efforts. The Karasu River in eastern Turkey hosts viable populations of all freshwater mussel species of the Orontes's fauna and can be considered one of the most important water bodies for the conservation of these imperiled animals in the region. [ABSTRACT FROM AUTHOR]

Freshwater mussels (Bivalvia: Unionoida) play an important role in freshwater habitats as ecosystem engineers of the water environment. Duck mussel Anodonta anatina is widely distributed throughout Europe, Siberia, and Western and Central Asia, which makes it a convenient object for biogeographic studies. In this study, we analyzed the divergence of A. anatina populations and discovered a separate genetic lineage distributed in rivers of the Azov Sea basin. This was confirmed by the high genetic distances between this group and previously defined populations, and by the position of this clade in the Bayesian phylogeny calibrated by an external substitution rate. Based on our approximate Bayesian computation (ABC) analysis, biogeographic scenarios of A. anatina dispersal in Europe and Northern, Western, and Central Asia over the Neogene–Quaternary were simulated. The haplogroup's isolation in the rivers of the Azov Sea basin most likely occurred in the Late Pliocene that was probably facilitated by rearrangement of freshwater basins boundaries in the Ponto-Caspian Region. Population genetic indices show the stability of this group, which allowed it to exist in the river basins of the region for a long time. The discovery of a long-term refugium in the rivers of the Azov Sea led to a better understanding of freshwater fauna evolution in the Neogene–Quaternary and highlighted the importance of conservation of these freshwater animals in the region as a source of unique genetic diversity. [ABSTRACT FROM AUTHOR]

In this work, we present an integrative revision of the Lymnaeidae from the northeastern margin of Asia (Far East Russia, Japan, and Korea) and Alaska. According to our results, 14 native species inhabit this region, belonging to eight genera in two subfamilies (Lymnaeinae: Dallirhytis , Galba , Walhiana , Ladislavella , and Lymnaea ; and Amphipepleinae: Kamtschaticana , Orientogalba , and Radix). Four of these species are new to science and three of them are described in this paper. Additionally, three established alien species are recorded from Japan (Pseudosuccinea columella , Galba schirazensis , and Galba humilis). The Japanese Archipelago represents an evolutionary hotspot of pond snail diversity, encompassing seven native species, three of which are endemic. The faunal connections between North America and northeastern Asia are discussed in the context of historical biotic interchange across the Beringian Land Bridge. Two cold-tolerant pond snails share high-latitude but localized ranges, being endemic to the Beringian Arctic: Dallirhytis atkaensis (Chukchi Peninsula, Alaska, and Aleutian Islands) and Walhiana arctica comb. nov. (Alaska). Our findings indicate that the Beringian Land Bridge has played a role in freshwater faunal exchanges between northeastern Asia and western North America. [ABSTRACT FROM AUTHOR]

The subfamily Sphaeriinae is a diverse and ecologically significant group of freshwater invertebrates, playing a keystone role in the energy flow and nutrient cycling in aquatic ecosystems. Despite a long history of its study, the taxonomic structure and species content of this group are a matter of ongoing disputes between malacologists. We clarify the taxonomy, distribution, and evolutionary biogeography of the Sphaeriinae around the world based on the largest dataset of DNA sequences of these clams ever accumulated, which includes the data on specimens collected from various continents and countries around the globe. Our 16S rRNA and two-locus phylogenies reveal that the Sphaeriinae is a monophyletic group, containing at least seven genus-level clades: Sphaerium Scopoli, 1777, Pisidium C. Pfeifffer, 1821 (s.s.), Euglesa Jenyns, 1832, Odhneripisidium Kuiper, 1962, Conventus Pirogov & Starobogatov stat. nov. 1974, 'Pisidium' sterkianum group, and Hindupisidium Vinarski & Bespalaya gen. nov. Our 16S rRNA phylogenetic tree contains 80 well-supported clades corresponding to the putative species-level taxa. Four species new to science are described here: Euglesa kolymensis Bespalaya, Aksenova & Bolotov sp. nov. , Euglesa kyrgyzica Bespalaya, Aksenova, Kondakov & Palatov sp. nov. , Euglesa moroccana Bespalaya, Vinarski, Aksenova, Mabrouki, Kondakov & Palatov sp. nov. , Odhneripisidium caucasus Bespalaya, Vinarski, Aksenova, Kondakov & Palatov sp. nov. Our fossil-calibrated phylogeny and generalized biogeographic model indicate that the most recent common ancestor of the Sphaeriidae could have originated somewhere within a broad area covering China near the Lower Cretaceous boundary. [ABSTRACT FROM AUTHOR]

Freshwater mussels (Unionida) are one of the most imperiled animal groups worldwide, revealing the fastest rates of extinction. Habitat degradation, river pollution and climate change are the primary causes of global decline. However, biological threats for freshwater mussels are still poorly known. Here, we describe a diverse ecological group of leeches (Hirudinea: Glossiphoniidae) inhabiting the mantle cavity of freshwater mussels. So far, examples of mussel-associated leech species are recorded from East Asia, Southeast Asia, India and Nepal, Africa, and North America. This group comprises a dozen glossiphoniid species with a hidden life style inside the mantle cavity of their hosts largely overlooked by researchers. We show that the association with freshwater mussels evolved independently in three leech clades, i.e. Batracobdelloides, Hemiclepsis, and Placobdella, at least since the Miocene. Seven mussel-associated leech species and two additional free-living taxa are described here as new to science. [ABSTRACT FROM AUTHOR]

The razor clam genus Novaculina represents an example of a marine-derived, secondary freshwater group. It was thought to comprise three species: N. gangetica (Ganges and smaller basins in Bangladesh and northwestern Myanmar), N. siamensis (Bang Pakong and Pasak rivers in Thailand and Mekong River in Vietnam), and N. chinensis (lower Yangtze River, China). Here we describe Novaculina myanmarensis sp. nov., an additional species from the Ayeyarwady and Salween basins representing a divergent lineage that appears to be sister to N. gangetica. This new record closes a Novaculina range disjunction between northwestern Myanmar and Thailand. The populations of this novel species share a shallow molecular divergence from each other indicating potential dispersal events between the two distant freshwater basins during the Late Pleistocene. Our ancestral area modeling suggests that the MRCA of Novaculina crown group was a salt-tolerant freshwater species. The recent Novaculina species most likely originated via allopatric speciation. Our findings highlight that generalist estuarine species could have played the role as a source for bivalve expansions into freshwater and that western Indochina is a separate biogeographic subregion, which is clearly distinct from India. A new synonymy is proposed as follows: Pharellinae Stoliczka, 1870 = Novaculininae Ghosh, 1920 syn. nov. [ABSTRACT FROM AUTHOR]

Bioerosion is a process with a high socio-economic impact that contributes to coastal retreat, and likely to increase with climate change. Whereas limestone bioerosion is well explained by a combination of mechanical and chemical pathways, the bioerosion mechanisms of silicates, which are harder and chemically more resistant, remain elusive. Here we investigated the interface between siltstone and freshwater rock-boring bivalves Lignopholas fluminalis (Bivalvia: Pholadidae). Remains of a microbial biofilm were observed only in the poorly consolidated part of the rock within the macroborings created by bivalves. Secondary Mn-bearing minerals identified in the biofilm suggest that microbes promoted silicate rock weathering by dissolving Mn-rich chlorites. Moreover, hard mineral debris found in a biofilm attached to the shells likely contributed to the abrasion of the rock substrate. Thus, beyond the classical view of chemical and/or mechanical action(s) of macroborers, silicate bioerosion may also be facilitated by an unexpected synergistic association between macro- and microorganisms. [ABSTRACT FROM AUTHOR]

The proliferation of genomic sequencing approaches has significantly impacted the field of phylogenetics. Target capture approaches provide a cost‐effective, fast and easily applied strategy for phylogenetic inference of non‐model organisms. However, several existing target capture processing pipelines are incapable of incorporating whole genome sequencing (WGS). Here, we develop a new pipeline for capture and de novo assembly of the targeted regions using whole genome re‐sequencing reads. This new pipeline captured targeted loci accurately, and given its unbiased nature, can be used with any target capture probe set. Moreover, due to its low computational demand, this new pipeline may be ideal for users with limited resources and when high‐coverage sequencing outputs are required. We demonstrate the utility of our approach by incorporating WGS data into the first comprehensive phylogenomic reconstruction of the freshwater mussel family Margaritiferidae. We also provide a catalogue of well‐curated functional annotations of these previously uncharacterized freshwater mussel‐specific target regions, representing a complementary tool for scrutinizing phylogenetic inferences while expanding future applications of the probe set. [ABSTRACT FROM AUTHOR]

The depressed river mussel Pseudanodonta complanata (Rossmässler, 1835) is an endangered freshwater bivalve with sparse distribution across Europe. Despite its high conservation priority, available data on the current population genetics and biogeography of P. complanata are very limited. In this paper, we studied the genetic diversity and differentiation of P. complanata based on newly sequenced COI and ND1 gene fragments, and on available sequences from the NCBI GenBank. We discovered a localized and highly divergent lineage in the Don River basin and a widespread but low diversified lineage distributed from the Volga River basin to the Oise River in France. A star-like haplotype network, results of mismatch analysis, and significant negative values of neutrality tests reveal that the pan-European lineage went through a bottleneck event. The discovery of the separate lineage in the Don River basin is and additional evidence of the existence of Pleistocene glacial refugia in the south of the Russian Plain. Moreover, this finding confirms the significance of the Azov Sea drainage as a freshwater biodiversity hotspot of great conservation importance. [ABSTRACT FROM AUTHOR]

Hot (geothermal) pools and streams, a specific type of aquatic biotopes having almost worldwide distribution, maintain rich faunas of animals belonging to various taxa. Snails (Gastropoda) represent one of such groups, which form populations in geothermal waterbodies of all continents. Some freshwater snail species produce morphologically distinct hot-water populations, whose rank is often debated (full species or thermal 'ecotype', or 'race'). In this study, we used six species of pond snails (family Lymnaeidae) to investigate the morphological and genetic consequences of infiltration of freshwater snails into geothermal habitats. In particular, we aimed at studying the changes in shell shape and proportions as well as the formation of unique hot-water haplotypes and the occurrence of the latter beyond geothermal waterbodies. All six species studied demonstrate diminutive body size in hot sites accompanied, in four species, by apparent alterations in shell proportions. A phenomenon of phenotypic 'juvenilization', when adult and able to reproduce individuals demonstrate shell proportions characteristic for full-grown individuals living under 'normal' conditions, is described. Unique 'thermal' haplotypes, not found beyond the geothermal sites, were normally restricted to a single locality, and no signs of frequent 'travels' of snails from one thermal habitat to another are seen. In the vast majority of cases, these exclusive haplotypes are separated from their ancestors by only a few (1–3) mutational steps, which may indicate their relatively recent origin. We are inclined to relate both size reduction and 'juvenilization' to the life-cycle re-adjustment following the penetration of lymnaeids to thermal habitats. The ecological ('thermal') intraspecific races of different species, forming in geothermal habitats, exhibit, to a great extent, evolutionary predictability (=convergent evolution; =parallelisms). The dilemma 'ecological race vs. young species' in application to the taxonomy of these hot-water populations is briefly discussed. [ABSTRACT FROM AUTHOR]

Currently, the parasitic and endosymbiontic fauna of Corbicula clams remain poorly studied throughout their range. Here, using samples from the Mekong basin, we describe two Symbiocloeon species new to science: Symbiocloeon corbiculinus sp. nov. and Symbiocloeon laoensis sp. nov. Our results and a review of available published data indicate that freshwater bivalve-associated mayflies are narrow host specialists, being associated with one or a few closely related species of freshwater bivalves. The bivalve-associated mayfly larvae have several specific morphological traits compared with free-living species, which include a reduction of integument chitinization and a significant reduction of the surface structures on segments. An increase in area of the respiratory surface of larval tergalia was also recorded. The possible positive and negative effects of mayflies on the clam hosts are discussed. This study is an example of the many possible hidden associations between aquatic species that remain to be described. [ABSTRACT FROM AUTHOR]

The duck mussel Anodonta anatina is widely distributed throughout the freshwater basins of Northern, Central, and Western Eurasia, and it has a comprehensive genetic structure. This study was devoted to the analysis of lineages, which are defined based on COI gene sequences. Our new dataset was expanded by samples from freshwater basins of Northern and Central Eurasia. It allowed us to reveal a high level of genetic diversity for the widely distributed trans-Eurasian lineage of A. anatina for the first time. As for results, representative samples from the Russian Plain, Southern Siberia, and the Ural region showed the presence of multiple interactions between duck mussel populations, indicating the existence of connections between freshwater basins in this region during the Late Quaternary. The genetic group from the freshwater basins of Northern Eurasia may be divided into two sub-lineages, which have differences in genetic structure and distribution patterns. It was revealed that there was a post-glacial expansion of duck mussels in the freshwater basins of Northern Eurasia after deglaciations of these territories and that the wide distribution of this species in this region was shaped via ancient connections between periglacial waterbodies. The lineage of A. anatina from the Ponto-Caspian region is a genetically rich and diverged group, which is present in the riverine basins of West-Central Asia related to the Caspian Sea. [ABSTRACT FROM AUTHOR]

We identified 14 emerging and poorly understood threats and opportunities for addressing the global conservation of freshwater mussels over the next decade. A panel of 17 researchers and stakeholders from six continents submitted a total of 56 topics that were ranked and prioritized using a consensus‐building Delphi technique. Our 14 priority topics fell into five broad themes (autecology, population dynamics, global stressors, global diversity, and ecosystem services) and included understanding diets throughout mussel life history; identifying the drivers of population declines; defining metrics for quantifying mussel health; assessing the role of predators, parasites, and disease; informed guidance on the risks and opportunities for captive breeding and translocations; the loss of mussel–fish co‐evolutionary relationships; assessing the effects of increasing surface water changes; understanding the effects of sand and aggregate mining; understanding the effects of drug pollution and other emerging contaminants such as nanomaterials; appreciating the threats and opportunities arising from river restoration; conserving understudied hotspots by building local capacity through the principles of decolonization; identifying appropriate taxonomic units for conservation; improved quantification of the ecosystem services provided by mussels; and understanding how many mussels are enough to provide these services. Solutions for addressing the topics ranged from ecological studies to technological advances and socio‐political engagement. Prioritization of our topics can help to drive a proactive approach to the conservation of this declining group which provides a multitude of important ecosystem services. [ABSTRACT FROM AUTHOR]

(i-k) Differently sized chironomid larvae from the cavity of C. fluminea, Sein Kaphoe River, Laos, 14.7710N, 106.1704E, 3 March 2020. gl In summary, it was discovered for the first time that mayflies, chironomids, and fishes can use the I Corbicula i clams as a host for their larval development (Figure 1; Appendix S1: Table S1). Keywords: chironomids; Corbicula clams; endosymbionts; gudgeon; larvae; mayfly EN chironomids Corbicula clams endosymbionts gudgeon larvae mayfly 1 5 5 01/04/23 20230101 NES 230101 In a sense, a single individual host can be considered an ecosystem. It is noteworthy to mention that one I Corbicula i contained both chironomid and mayfly larvae (Figure 1g), and two clams had two chironomid larvae under the mantle of the right and the left valves. Chironomids, Corbicula clams, endosymbionts, gudgeon, larvae, mayfly. [Extracted from the article]

Southern Thailand represents a region of unique freshwater biodiversity with many endemic taxa, including a number of freshwater mussel species (Bivalvia: Unionidae). In this study, we recognize 13 taxa in the tribes Contradentini, Rectidentini, Pseudodontini (subfamily Gonideinae), and Indochinellini (subfamily Parreysiinae) that inhabit different localities in the Songkhla Lake, Tapi River, and Tha Taphao River basins. Based on the results of morphological and phylogenetic analyses, we discovered among these mussels six taxa new to science, including one genus, three species, and two subspecies. New taxonomic names are introduced here as follows: Songkhlanaiagen. nov.; S. tamodienicagen. & sp. nov.; Sundadontina plugpomenicasp. nov.; Monodontina vondembuschiana tapienicassp. nov.; M. vondembuschiana thasaenicassp. nov. (Pseudodontini); and Trapezoideus thachiadensissp. nov. (Contradentini). These new taxa confirm the high conservation priority of the Southern Thai freshwater mussel fauna. [ABSTRACT FROM AUTHOR]

Currently, the validity of many nominal bivalve species of the genus Corbicula endemic to the Russian Far East and South Korea needs a critical reassessment. In this study, we clarify the taxonomic status of Corbicula species of this area based on a combination of molecular genetic, conchological and anatomical data. According to our results, four Corbicula lineages, corresponding to the nominal species Corbicula japonica , Corbicula elatior , Corbicula leana and Corbicula fluminea , can be delineated in samples collected in the Primorye and Khabarovsk regions of Russia and South Korea. Two species endemic to the Russian Far East (i.e. Corbicula finitima and Corbicula lindholmi) are considered here as junior synonyms of the species C. japonica , which is widely distributed in estuarine habitats around the Japanese Archipelago, Sakhalin Island, southern Kurile Islands, Primorye and Khabarovsk regions, Korean Peninsula and China. Three nominal species described from the Lower Amur basin (Corbicula amurensis , Corbicula nevelskoyi and Corbicula sirotskii) appeared to be synonyms of C. elatior , whose range covers the Korean Peninsula, Primorye and Khabarovsk regions and, perhaps, China. We delineated several colour morphs of C. fluminea and C. japonica. The distinctness between these colour morphs can be attributed to both heritable and environmental factors. [ABSTRACT FROM AUTHOR]

Here we describe a new subgenus and three new species of parasitic water mites in the genus Unionicola (Acari: Hydrachnidia) from Myanmar: Myanmaratax subgen. nov., Unionicola (Myanmaratax) savadiensis subgen. and sp. nov. (hosts: Lamellidens savadiensis and L. generosus), U. (My.) generosa sp. nov. (the same hosts), and U. (My.) trapezidenssp. nov. (hosts: Trapezidens dolichorhynchus and T. angustior). These taxa were identified based on a two-gene phylogenetic analysis (COI + 28S), which also confirms the division of the genus Unionicola into numerous subgenera. The new species are cryptic species, which are morphologically indistinguishable but strongly resemble U. (Prasadatax) brandti Vidrine, 1985 described from Thailand (hosts: Lens spp. and Ensidens spp.). We also transfer the latter taxon from Prasadatax to Myanmaratax based on a set of morphological evidence and propose U. (My.) brandti comb. nov. The new subgenus contains a total of five species, one of which needs future sampling efforts and will be described elsewhere. Additionally, 56 valid subgenera, which were placed in the synonymy of the genus and in one case raised to the genus level, are restored here until robust phylogenetic evidence on their taxonomic status is available. Our results also confirm that Unionicola mites are narrow host specialists that are associated with either one or a few closely related freshwater mussel species belonging to one or two sister genera. [ABSTRACT FROM AUTHOR]

The bumble bee fauna of the Russian Arctic is rather poorly known. Kolguev Island, a remote insular territory in the Barents Sea, is one of the deficiently studied areas. In this study, material on Kolguev's bumble bees is re-examined, phylogeographic data analysed, putative scenarios explaining the origin of the bumble bee fauna on the island discussed, and the biology and phenology of these insular populations described. Five bumble bee species, i.e., Bombus flavidus, B. lapponicus, B. jonellus, B. pyrrhopygus, and B. balteatus, were recorded on this island. All of these species are widespread throughout the Eurasian Arctic. Bumble bee populations on Kolguev Island are characterised by a low level of molecular divergence from mainland populations. Based on paleogeographic reconstructions and phylogeographic patterns, it is hypothesised that the bumble bees appeared on this island in the Early Holocene. The lack of rodents (lemmings and voles) sharply decreases the number of available nesting places for bumble bees on Kolguev Island. [ABSTRACT FROM AUTHOR]

The high‐elevation Tibetan Plateau (western China) is inhabited by a unique, though not particularly species‐rich, community of organisms. We explored the species content and evolutionary history of the Tibetan Plateau endemic freshwater snail genus Tibetoradix. Phylogenetic relationships within the genus were reconstructed based on available sequence data. We used a single‐rate Poisson Tree Processes approach for species delimitation and compared putative species‐level clades with already described taxa. We found that the genus consists of at least 6 species, of which we described 4 as new to science. Shell and soft body morphology was examined and the radula in Tibetoradix was described for the first time. Based on our findings, the diversification of the genus did not result in a prominent morphological differentiation and a number of species can be regarded as morphologically cryptic. Single species found in different drainage areas indicate relatively good passive dispersal abilities of the snails. The allopatric distribution of the species could result from competitive exclusion between them. The absence of Tibetoradix spp. outside the Tibetan Plateau could be explained by a scenario of an "evolutionary trap", where adaptations to high elevation conditions prevented the taxa from a successful colonization of lower elevations. [ABSTRACT FROM AUTHOR]

Currently, the reproductive mode of the Indonesian endemic species Corbicula tobae from Lake Toba is yet to be investigated. In this study, we describe, for the first time, the reproductive mode of this endemic species based on a series of topotype specimens, combining anatomical and histological data. According to our data, C. tobae is a dioecious species, incubating D-shaped larvae in the inner demibranchs and having monoflagellate sperm. The head of the C. tobae spermatozoon differs from those of other Indonesian species of Corbicula by having the smallest length. A histological investigation of C. tobae gills revealed that the inner demibranch has larger interlamellar spaces compared with the outer demibranches. Our study highlights several specific reproductive traits may have evolved in narrowly endemic Corbicula clams within their native ranges. [ABSTRACT FROM AUTHOR]

The freshwater pearl mussel Margaritifera margaritifera is a unionid species distributed across Northwestern Russia, Fennoscandia, Western and Southwestern Europe, and the Atlantic Coast of North America. In this study, we reconstructed the post-glacial expansion routes of this species based on FST genetic distances and the fact that M. margaritifera distribution is directly connected with salmonid expansion. The freshwater-pearl-mussel populations from North America and Northeastern Europe were the closest groups, judging by FST distances, supporting the concept of the North Atlantic Salmo salar colonization of the Barents and White Sea basins. We also documented that unique haplotypes in the populations of the Baltic and White Sea basins may have originated in isolated glacial refugia in Eastern and Northeastern Europe. The Iberian clade was the most distant group of populations, which is consistent with the previously observed role of the Iberian Peninsula as a glacial refugium. The high genetic diversity in the populations of Northern and Eastern Karelia was facilitated by migrants utilizing complex periglacial hydrological networks and by admixture in the contact zone where the migration flows met. We confirm that this region should be considered as a major center of genetic diversity within the European part of the species' range. [ABSTRACT FROM AUTHOR]

India represents a tropical biodiversity hotspot, harbouring a unique and largely endemic fauna of freshwater mussels (Bivalvia: Unionidae). Unfortunately, the type series of many freshwater mussel taxa historically described from this country are thought to be lost. Here, we report on the rediscovery of the type series of Parreysia corrugata (O.F Müller, 1774) (Parreysiinae: Parreysiini) in the Natural History Museum of Denmark (NHMD), Copenhagen. It contains four syntypes (complete shells), which were examined by means of morphological and geometric morphometric techniques. We show that the nominal taxon Parreysia corrugata was established based on a composite type series, because one of the syntypes belongs to another species, Potomida semirugata (Lamarck, 1819) (Gonideinae: Lamprotulini), originating from the Middle East. To fix the taxonomic identity of the Indian species, a syntype (lot NHMD 916309) that was most likely illustrated by O.F. Müller in 1779 is designated here as the lectotype of Parreysia corrugata. The lectotype, paralectotypes and corresponding labels are illustrated in detail. Our new findings clarify the taxonomic concept of Parreysia corrugata and contribute to the further development of the Indian Unionidae taxonomy. [ABSTRACT FROM AUTHOR]

The faunal, molecular, and palaeogeographic data that make it possible to discuss where and when aquatic animals could have crossed the watershed divide between the basins of the Caspian Sea and the Arctic Ocean are discussed. The freshwater fauna of Europe and northern Asia were largely similar in the Pliocene, while Pliocene fauna in Siberia went almost totally extinct during the Pleistocene glaciations. In interglacial periods, cold-water freshwater organisms colonized the Volga River basin, most likely during dispersal events from the basins of the Pechora and Ob' rivers. Marine animals might have found their way into the Caspian Sea with saline waters arriving from the Arctic Ocean in the late Pliocene and early Pleistocene epochs. There was probably no possibility to cross the watershed divide during the last glacial period. After this period had ended, freshwater organisms, including mostly warm-water groups, entered the basins of the Onega, Northern Dvina, and Ob' rivers as the watershed divide shifted to another location. Similar expansions currently take place due to human-mediated introduction and dispersal events through the channels connecting the Volga and Northern Dvina river basins. [ABSTRACT FROM AUTHOR]

Diverse associations of freshwater sponges with molluscs were recently described from the Xingu River, Amazon Basin. However, such associations in other parts of the world are almost unknown. Here, we report on the discovery of epifaunal associations of a freshwater sponge (Corvospongilla, Spongillidae) with a byssus‐attaching clam (Limnoperna, Mytilidae) and a freshwater mussel (Hyriopsis, Unionidae) in tropical Asia (Mun River, Thailand). We used this association as a model system to show how the application of an integrative taxonomic approach can change modern views on the taxonomic status and biogeographic affinities of tropical invertebrates in a rather small sample. The freshwater sponge from the Mun River morphologically corresponds to the nominal taxon Corvospongilla siamensis but it is identical to Corvospongilla ultima from the Kaladan River, western Myanmar, based on the sequences of five DNA markers and the PTP species delimitation modeling. Hence, the first species is considered here to be a junior synonym of C. ultima. Conversely, the Limnoperna clam from the Mun River is found to be distant phylogenetically from the invasive golden mussel Limnoperna fortunei based on the sequences of three DNA markers. We therefore restore Limnoperna siamensisstat. rev. as a valid species. Our time‐calibrated multi‐locus phylogeny reveals that the split between L. siamensis and L. fortunei most likely occurred at the Miocene—Pliocene boundary. Finally, the freshwater mussel Hyriopsis khoratensis is an abundant species endemic to the Mun River. Our novel data highlight that associations of freshwater sponges with bivalves are present in Asia but were historically overlooked there and that the Mekong's sponge‐mollusc association can be considered analogous to those discovered in South America. [ABSTRACT FROM AUTHOR]

Discoveries of new Hemiclepsis species (Hirudinea: Glossiphoniidae) in East and Southeast Asia were expected. A peculiar freshwater leech was found on the body surface of Asian Swamp Eel Monopterus albus (Synbranchiformes: Synbranchidae) in Jingzhou, Hubei Province, China. Here, we describe this leech species as Hemiclepsis yangtzenensissp. nov. It could be distinguished from other congeners based on a combination of morphological features such as very small size, translucent body with dense green reticulate markings throughout dorsum, very large posterior sucker with a characteristic reticulate pattern, and two pairs of well-developed drop-like eyespots. It also represents a phylogenetic lineage that is distant from other members of the genus based on the COI and 18S rRNA sequences. This leech species seems to be a specialized fish parasite that could negatively affect farming and wild stocks of Asian Swamp Eel in China. [ABSTRACT FROM AUTHOR]

North Sumatra's Lake Toba is a famous example of a supervolcano caldera, being the world's deepest and largest crater lake. It has been originated since the massive Toba eruption of 74,000 years ago that coincides with global environmental shifts and a significant bottleneck in the global human population. While the freshwater fauna of this lake does not share high levels of endemism, there is Corbicula tobae, an Asian clam species that was described as a taxon endemic to Lake Toba. Here we confirm the validity of this species using morphological, anatomical, and DNA‐based evidences, although the general species‐level concept for this genus is yet to be developed. Additionally, Corbicula leana, a widespread invasive species, was recorded from Lake Toba for the first time. These two species living in sympatry in Lake Toba appear to exploit different ecological niches within the lake. [ABSTRACT FROM AUTHOR]

The taxonomic position of three nominal species of lymnaeid snails placed by Kruglov & Starobogatov (1993) into the subgenus Lymnaea (Pacifimyxas) Kruglov & Starobogatov, 1985, has been re‐assessed based on a molecular genetic study of topotypic specimens and an examination of the type series and other materials available. It has been shown that the two species, Lymnaea (Pacifimyxas) magadanensis Kruglov & Starobogatov, 1985 and Lymnaea (Pacifimyxas) streletzkajae Kruglov & Starobogatov, 1985, are identical with the species Kamtschaticana kamtschatica (Middendorff, 1850) and must be treated as its junior synonyms. Hence, Pacifimyxas becomes a junior synonym of Kamtschaticana Kruglov & Starobogatov, 1984. The taxonomic identity of the third species of Pacifimyxas, Lymnaea (Pacifimyxas) perpolita, remains obscure, and this species is considered here as taxon inquirendum. Two other nominal species, Lymnaea aberrans (Westerlund, 1897) and Lymnaea middendorffi (W. Dybowski, 1904), have been synonymized with K. kamtschatica based on morphological and geographical evidence. The lectotype of Limnaea peregra var. middendorffi is designated. The actual level of species richness in the Beringian freshwater malacofauna may be 20–25% lower than it was determined on the basis of the traditional system. Some implications of this outcome for the biogeography of the Beringian freshwater fauna are discussed. [ABSTRACT FROM AUTHOR]

In this review, we synthesize the current knowledge of the biology, ecology, and impact of Sinanodonta freshwater mussels (Bivalvia, Unionidae), native to East Asia, that have successfully invaded Europe, Central America, North Africa, and several Asian regions. The main introduction pathways of Sinanodonta were reconstructed based on DNA sequence data and distribution records. We show that invasive lineages of Sinanodonta belong to three species, namely, S. woodiana s. str. (“temperate invasive” lineage), S. pacifica (“tropical invasive” lineage), and S. lauta. Their generalist fish-dispersed larvae, short life span, high fecundity, use by humans for multiple purposes, and ability to establish populations in anthropogenically disturbed conditions were identified as crucial traits driving their invasions. Information on the consequences is scarcer, but Sinanodonta can impact native species through larval parasitism, host fish/food competition, and parasite transmission. In addition, ecosystem effects through their filtration—biodeposition—excretion activity and the occurrence of massive die-offs were detected. Ecosystem services and disservices have not yet been quantified, even at local scales, and management methods in the invasive range are understudied. A better understanding of Sinanodonta ecology, impacts, and management options is urgently needed to make informed decisions and set realistic and impactful restoration goals. [ABSTRACT FROM AUTHOR]

The High Arctic bumble bee fauna is rather poorly known, while a growing body of recent molecular research indicates that several Arctic species may represent endemic lineages with restricted ranges. Such local endemics are in need of special conservation efforts because of the increasing anthropogenic pressure and climate changes. Here, we re-examine the taxonomic and biogeographic affinities of bumble bees from Novaya Zemlya using historical samples and recently collected materials (1895-1925 vs. 2015-2017). Three bumble bee species inhabit the Yuzhny (Southern) Island and the southern edge of Severny (Northern) Island of this archipelago: Bombus glacialis Friese, 1902, B. hyperboreus Schönherr, 1809, and B. pyrrhopygus Friese, 1902. Bombus glacialis shares three unique COI haplotypes that may indicate its long-term (pre-glacial) persistence on Novaya Zemlya. In contrast, Bombus hyperboreus and B. pyrrhopygus share a rather low molecular divergence from mainland populations, with the same or closely related haplotypes as those from Arctic Siberia and Norway. A brief re-description of Bombus pyrrhopygus based on the newly collected topotypes is presented. Habitats, foraging plants and life cycles of bumble bees on Novaya Zemlya are characterized, and possible causes of extremely low bumble bee abundance on the archipelago are discussed. The species-poor bumble bee fauna of Novaya Zemlya is compared with those in other areas throughout the Arctic. The mean bumble bee species richness on the Arctic Ocean islands is three times lower than that in the mainland Arctic areas (3.1 vs. 8.6 species per local fauna, respectively). General linear models (GLMs) indicate that this difference can be explained by specific environmental conditions of insular areas. Our findings highlight that the insularity is a significant factor sharply decreasing species richness in bumble bee assemblages on the Arctic Ocean archipelagoes through colder climate (lower summer temperatures), prevalence of harsh Arctic tundra landscapes with poor foraging resources, and in isolation from the mainland. [ABSTRACT FROM AUTHOR]

Abstract Freshwater mussels are declining globally, and effective conservation requires prioritizing research and actions to identify and mitigate threats impacting mussel species. Conservation priorities vary widely, ranging from preventing imminent extinction to maintaining abundant populations. Here, we develop a portfolio of priority research topics for freshwater mussel conservation assessment. To address these topics, we group research priorities into two categories: intrinsic or extrinsic factors. Intrinsic factors are indicators of organismal or population status, while extrinsic factors encompass environmental variables and threats. An understanding of intrinsic factors is useful in monitoring, and of extrinsic factors are important to understand ongoing and potential impacts on conservation status. This dual approach can guide conservation status assessments prior to the establishment of priority species and implementation of conservation management actions. Highlights • We develop a portfolio of priority research topics for freshwater mussel conservation assessment. • The portfolio summarizes the knowledge of a multidisciplinary, global team of scientists working in this area. • Research priorities are divided into two categories, intrinsic and extrinsic factors. • We discuss how practitioners can leverage this information to improve conservation actions. [ABSTRACT FROM AUTHOR]

Associations of various invertebrate species with bryozoans and sponges are a well-known marine phenomenon but such epizooic communities are far less diverse in freshwater environments. Here an occurrence of numerous leeches Alboglossiphonia cf. papillosa (Braun, 1805), in interstitial spaces between zooids of a colony of the freshwater bryozoan species Plumatella aff. fungosa (Pallas, 1768) in Eastern Siberia is described. To the best of our knowledge, this record appears to be the first known example of a leech-bryozoan association, although such relationships deserve further research. [ABSTRACT FROM AUTHOR]

Burial histories of the eastern, central and western parts of the Northern Caucasus basin are reconstructed on the basis of well data and seismic sections. Subsidence began in the Early Triassic after the Late Carboniferous–Permian orogeny. Triassic sediments were mainly removed during Late Triassic–Early Jurassic uplift and erosion. Platform cover began to form in the Middle Jurassic and Albian sediments covered the whole territory of the basin. Thermal modelling shows that Jurassic–Eocene subsidence was mainly controlled by Late Triassic–Early Jurassic intrusive warming. This heating event induced thermal uplift of the whole territory followed by exponentially decelerating subsidence due to cooling of the lithosphere. In the southern areas adjacent to Great Caucasus, subsidence was also affected by Caucasian extensional and compressional events. In the Oligocene–Early Miocene, the eastern and the central basins underwent rapid long wavelength subsidence (Maikopian subsidence). The geodynamic cause of this subsidence is probably associated with the mantle flow appearance after cessation of the Tethyan subduction, due to reequilibration of subducted slab. While in the Late Miocene–Quaternary times, the eastern and the western basins underwent foreland-type asymmetrical subsidence due to loading of the Great Caucasus orogen; the central basin was uplifted. According to flexural modelling, the main component of orogen loading was the lithospheric root load; delamination of the latter under the Central Caucasus caused rapid uplift of the orogen and adjacent basin. [Copyright &y& Elsevier]

[Display omitted] • Freshwater mussels were surveyed comprehensively in the East Mediterranean Region. • Voucher specimens and tissue snips were collected for genetics. • COI barcoding and species delineation methods are applied to all available genera. • New phylogeny and systematics of the East Mediterranean Unionidae are provided. • Biogeographic and conservation considerations are provided. Located at the junction between Europe, Africa, and Asia, with distinct evolutionary origins and varied ecological and geographical settings, together with a marked history of changes in orogeny and configuration of the main river basins, turned the Eastern Mediterranean into a region of high diversity and endemism of freshwater taxa. Freshwater mussels (Bivalvia, Unionidae) from the Western Palearctic have been widely studied in their European range, but little attention has been dedicated to these taxa in the Eastern Mediterranean region and their diversity and phylogeography are still poorly understood. The present study aims to resolve the diversity, biogeography, and evolutionary relationships of the Eastern Mediterranean freshwater mussels. To that end, we performed multiple field surveys, phylogenetic analyses, and a thorough taxonomic revaluation. We reassessed the systematics of all Unionidae species in the region, including newly collected specimens across Turkey, Israel, and Iran, combining COI + 16S + 28S and COI phylogenies with molecular species delineation methods. Phylogeographical patterns were characterized based on published molecular data, newly sequenced specimens, and species distribution data, as well as ancestral range estimations. We reveal that Unionidae species richness in the Eastern Mediterranean is over 70% higher than previously assumed, counting 19 species within two subfamilies, the Unioninae (14) and Gonideinae (5). We propose two new species, Anodonta seddoni sp. nov. and Leguminaia anatolica sp. nov. Six additional taxa, Unio delicatus stat. rev. , Unio eucirrus stat. rev. , Unio hueti stat. rev. , Unio sesirmensis stat. rev. , Unio terminalis stat. rev. removed from the synonymy of Unio tigridis , as well as Unio damascensis stat. rev. removed from the synonymy of Unio crassus , are re-described. The nominal taxa Unio rothi var. komarowi O. Boettger, 1880 and Unio armeniacus Kobelt, 1911 are proposed as new synonyms of Unio bruguierianus , and Anodonta cyrea Drouët, 1881 and Anodonta cilicica Kobelt & Rolle, 1895 as new synonyms of Anodonta anatina. Also, the presence of Unio tumidus in the Maritza River is confirmed. The phylogeographic patterns described here are interpreted concerning major past geological events. Conservation needs and implications are presented, together with populations and species conservation priorities. [ABSTRACT FROM AUTHOR]