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A new species of freshwater mussel belonging to the genus Pseudocuneopsis, namely Pseudocuneopsis yangshuoensis sp. nov., is diagnosed and described from Guangxi Province, China. This paper provides a detailed morphological description, photograph of the type specimen, and anatomical characteristics along with partial sequences of mitochondrial COI as DNA barcode data for this novel species. The new species can be distinguished from its congeners (Pseudocuneopsis sichuanensis and Pseudocuneopsis capitata) by shell shape, beak position and surface sculpture. The interspecies genetic distance based on the COI barcode between P. yangshuoensis sp. nov. and P. sichuanensis is 8%, while it reaches 9% with P. capitata. Therefore, we provide robust morphological and molecular evidence to support the validity of this new species. [ABSTRACT FROM AUTHOR]

A new species of freshwater mussel belonging to the genus Pseudocuneopsis, namely Pseudocuneopsis wuana sp. nov., is diagnosed and described from Guangxi Province, China. This paper provides a detailed shell morphological description, soft-body anatomical characteristics, and partial sequences of mitochondrial COI as DNA barcode data for the novel species. The new species can be distinguished from its congeners (Pseudocuneopsis sichuanensis, P. yangshuoensis, and P. capitata) by shell shape, beak position, and surface sculpture. Phylogenetic analyses based on the mitochondrial COI gene reveal that Pseudocuneopsis wuana sp. nov. forms a sister group with P. yangshuoensis and exhibits an interspecific genetic distance of 5.1%. Therefore, we provide robust morphological and molecular evidence to support the validity of this new species. [ABSTRACT FROM AUTHOR]

Increasingly sophisticated molecular techniques and research tools have greatly advanced the understanding of species diversity and phylogenetic relationships in freshwater mussels. However, malacologists have been puzzled by the taxonomic position and species validity of certain species, particularly those described solely based on conchological characteristics. The genus Lepidodesma is one such group. Here, we integrate shell morphology, soft-body anatomy, and molecular phylogeny to delimit the species validity of Lepidodesma aligera (Heude in Conchyliologie Fluviatile de la Provoince de Nanking 3:17–24, 1877) and Lepidodesma languilati (Heude in Journal De Conchyliologie 22:112–118, 1874). Comparative morphology reveals that L. aligera can be distinguished from L. languilati by its higher post-dorsal wing covered with scattered nodules, as well as differences in the incurrent aperture, excurrent aperture, and gill. Additionally, the average genetic distance based on DNA barcodes (COI) between both species is 4.0%. Integrative taxonomy supports the distinct species of L. aligera, rather than synonymy for L. languilati. Mitochondrial phylogenomic analyses confirm four monophyletic groups (Ambleminae + (Gonideinae + (Unioninae + Parreysiinae))) within the family Unionidae. L. aligera and L. languilati have a well-supported sister-group relationship and form a basal clade splitting from the rest of Unioninae. Therefore, the genus Lepidodesma should be classified as Lepidodesmini in Unioninae. The molecular clock with fossil calibration indicates that Lepidodesma originated in the Early Cretaceous (~121.30 Mya, 95% HPD = 90.37–156.54 Mya) and diverged in the Middle Neogene (~12.94 Mya, 95% HPD = 6.72–22.13 Mya). This study firstly provides anatomical features and molecular data for L. aligera and demonstrates the species validity and the systematic position of Lepidodesma taxa, which enrich our understanding of this rare group and facilitate its management and conservation. [ABSTRACT FROM AUTHOR]

Accurate species identification is crucial for developing conservation strategies for freshwater mussels, one of the most imperiled faunas in the world. Traditionally, mussel species description primarily relied on conchological characters. However, shell morphology has great variability, which leads to the complexity of species delimitation. As endemic species to China, Lamprotula caveata was originally described by Heude (1877). Lamprotula quadrangulosus and Lamprotula contritus were considered for synonymization of L. caveata based on shell variants in the early 20th century, which has been long debated due to lack of rigorous molecular analysis. Moreover, great morphological variation caused doubt whether there are cryptic species. In this study, we used a combined phylogenetic and morphometric approach to verify the validity of the synonymization of L. caveata. The results of molecular species delimitation showed that two molecular operational taxonomic units (MOTUs) were identified in Lamprotula spp., including the L. leaii lineage and the complex lineage (L. quadrangulosa, L. cornuumlunae, L. contritus, and L. caveata). Phylogenetic analyses revealed that L. cornuumlunae formed a basal monophyletic clade, whose divergence time was relatively recent (4.26 Ma [95% HPD = 1.91–7.22 Ma]), and L. contritus, L. caveata, and L. quadrangulosa formed a large polytomy group with very shallow branches. In the previous study, we have demonstrated the validity of L. cornuumlunae. The molecular evidences supported that the complex (L. quadrangulosa + L. contritus + L. caveata) was a valid species; L. quadrangulosa and L. contritus were synonyms of L. caveata. In addition, three morphospecies (L. quadrangulosa, L. contritus, and L. caveata) were aggregated without clear differentiation based on shell morphometric analysis. We confirmed multiple phenotypes in L. caveata for species identification and presumed that the phenotypic plasticity was a response to specific habitats. This study clarified the diversity and phylogeny of the Lamprotula group, which is a crucial step for developing new conservation and management strategies for this imperiled group. [ABSTRACT FROM AUTHOR]

Freshwater mussels (Mollusca: Bivalvia: Unionida) have a broad global distribution on every continent except Antarctica. However, owing to human activities, the diversity of freshwater mussels is seriously globally threatened. China is an important global biodiversity hotspot for this fauna.This article comprehensively reviews the 99 currently recognized species in China, collating for the first time their systematics, distribution, life‐history traits, habitat preferences, conservation status, and main threats to suggest future management actions.The review showed that the taxonomic status and species validity of many freshwater mussels are still not well resolved. The freshwater mussel diversity in the Yangtze River Basin is higher than that in other freshwater habitats in China. Life history characteristics and habitat preferences are poorly known for most species.Only half of the total number of species in China have been assessed for their conservation status. Among those assessed, around half of them are threatened with extinction with more than 10% being considered as Data Deficient.The key threats identified as potentially related to species declines are pollution, habitat loss and fragmentation, loss of access to host fishes and overharvesting of mussels or their host fishes.The review shows that there is a strong geographical bias in the amount of knowledge available for freshwater mussels, with most of the available data being concentrated in the middle and lower reaches of the Yangtze basin. Almost no data are available for these taxa north of the Yellow River basin and in the west and south‐west regions of China.To make future conservation and management more effective we suggest that efforts should be concentrated on: (i) increasing the amount of research on basic ecological and life‐history features, including growth, life‐span, reproductive cycle, host fish identification and habitat requirements of each species; (ii) establishing the interspecific and intraspecific genetic diversity patterns of Chinese freshwater mussels, to clarify their taxonomy, systematics and phylogeny, and to understand the phylogeography and population structure of each species; and (iii) urgently establishing protected areas for fish and mussels in locations of high species richness, such as Poyang Lake and Dongting Lake, and also in regions with high levels of endemism or genetic uniqueness, such as Guangxi Province, Yunnan Province and Heilongjiang Province. In addition, the need for habitat restoration and the conservation of freshwater mussels has become urgent in China, and an integrated systematic conservation and management plan should be developed and effectively implemented. [ABSTRACT FROM AUTHOR]

The Yangtze River drainage in China is among the most species rich rivers for freshwater mussels (order Unionida) on Earth with at least 68 species known. The freshwater mussels of the Yangtze River face a variety of threats with indications that species are declining in abundance and area of occupancy. This study represents the first analyses of the genetic structure and diversity for the common and widespread freshwater mussel Nodularia douglasiae based on microsatellite DNA genotypes and mitochondrial DNA sequences. Phylogenetic analysis a fragment of the COI mitochondrial gene indicated that N. douglasiae collected from across the middle and lower Yangtze River drainage are monophyletic with N. douglasiae from Japan, Russia, and South Korea. The results of the analysis of both the mtDNA and microsatellite datasets indicated that the seven collection locations of N. douglasiae in the middle and lower Yangtze River drainage showed high genetic diversity, significant genetic differentiation and genetic structure, and stable population dynamics over time. Moreover, we found that the connections among tributaries rivers and lakes in the Yangtze River drainage were important in maintaining gene flow among locations that N. douglasiae inhabits. An understanding of the genetic structure and diversity of a widespread species like N. douglasiae could be used as a surrogate to better understand the populations of other freshwater mussel species that are more rare in the Yangtze River drainage. At the same time, these results could provide a basis for the protection of genetic diversity and management of unionid mussels diversity and other aquatic organisms in the system. [ABSTRACT FROM AUTHOR]