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The basic knowledge of freshwater bivalves in the Unionida in some regions of the world is still limited, hindering potential conservation efforts, including in Vietnam. A subset of these mussels, the freshwater bivalve tribe Anodontini, is especially difficult to properly identify morphologically due to intraspecific shell similarity. This study aims to define the species of Anodontini in Vietnam and describe their evolutionary relationships and distributions by estimating phylogenies and analyzing collected specimens. The Anodontini are represented in Vietnam by five species divided among three genera: Sinanodonta, Cristaria, and Pletholophus. Sinanodonta woodiana, a large species complex, is represented in Vietnam by Sinanodonta jourdyi. Cristaria is confirmed to include the widespread Cristaria plicata and substantiates the validity of Cristaria truncata. Finally, Pletholophus is here recognized as distinct from Cristaria, containing two species in Vietnam, Pletholophus tenuis, and a species new to science. Our study is an important baseline for future studies on Vietnamese freshwater mussels and highlights the importance of surveys, molecular work, and taxonomic expertise to describe the biodiversity of understudied regions.

Abstract Background Anthropogenic factors potentially affect observed biogeographical patterns in population genetics, but the effects of ancient human activities on the original patterns created by natural processes are unknown. Sinotaia quadrata, a widely distributed freshwater snail species in East Asia, was used to investigate this issue. It is unclear whether S. quadrata in Japan was introduced from China and how different human uses and varying geographic patterns affect the contemporary population genetics between the two regions. Thus, we investigated the demography of S. quadrata and detected its genetic structure in Japan and continental East Asia. Results Sinotaia quadrata populations first naturally migrated from continental East Asia to Japan, which is associated with the ancient period in Japanese geohistory (about 70,000 years ago). They were then artificially introduced in association with agriculture expansion by human movements in two recent periods (about 8,000 and 1,200 years ago). Populations in different parts of Japan have their own sources. Natural migration in the ancient period and artificial introduction in the recent period suggest that the population distribution is affected by both the geohistory of East Asia and the history of human expansion. In the background of the historical migration and introduction, contemporary populations in the two regions show different genetic patterns. Population divergence levels were significantly correlated with geographical patterns in Japan and significantly correlated with human interventions variables in continental East Asia, suggesting that long‐term geographical isolation is likely the major factor that shaped the contemporary population genetics in Japan, while modern human uses are likely the major factor in continental East Asia. Conclusions Our preliminary results show a complex demography and unusual genetic patterns in the contemporary populations for a common freshwater snail and are of significance to determine the historical formation and contemporary patterns of biogeography in Japan and continental East Asia.

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.

Case Presentation: A 44-year-old man consulted in April 2020 for a 1-week persistent left lateral chest pain, increased with deep breathing and change of position. He had left lower limb pain without redness or swelling 2 weeks before presentation. He did not complain of shortness of breath, cough, hemoptysis, syncope, fever, nor general status alteration. [ABSTRACT FROM AUTHOR]

Two new species of freshwater shrimp in the family Atyidae, Caridina tricincta and C. pacbo, are described from the provinces of Tuyen Quang and Ha Giang, and from the province of Cao Bang, respectively, all in northern Vietnam. The new species can be distinguished from congeners by distinct characteristics of the rostrum, first and second pereopods, and male first and second pleopods. Molecular phylogenetic analysis of the mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16S) genes also support the distinctiveness of the new species from all other examined species. [ABSTRACT FROM AUTHOR]

South-east Asian apple snails, Pila spp., have been declining since the introduction of globally invasive, confamilial South American Pomacea spp., yet Pila ecology remains poorly studied, with most occurrence records unconfirmed. Pila scutata , a previously widespread species, presumed native to the Malay peninsula and assessed as Least Concern in the IUCN Red List, was formerly harvested for food, and may have experienced anthropogenic translocations. We surveyed the Malay peninsula (specifically Peninsular Malaysia and Singapore) to investigate the current distribution and genetic diversity of P. scutata. Six populations were found in Singapore, but only one in Peninsular Malaysia. Mitochondrial COI and 16S sequencing revealed that the Malaysian population shared a single haplotype of both genes with the Singapore populations (500 km distant). This low genetic diversity could stem from a recent anthropogenic introduction, which brings into question the true native range of P. scutata and, coupled with poorly resolved taxonomy of the genus, necessitates a reassessment of its IUCN Red List status. Introduced populations pose a dilemma, and the lack of genetic diversity is of concern in light of Pila decline throughout South-east Asia. Our results highlight that conservation management of P. scutata and its congeners must therefore be better informed by greater taxonomic resolution and more comprehensive investigations of their ecology, both in native and introduced ranges. [ABSTRACT FROM AUTHOR]

During recent survey work and examination of museum collections in Hanoi, we became aware that a species misidentified in the literature was in fact a new and rare species of freshwater bivalve. It is currently known only from 12 dry valves in the collections in Hanoi, Vietnam and 2 valves in the North Carolina Museum Collection. These specimens resemble the eastern Chinese genus Pseudobaphia Simpson, 1900. We describe these specimens from the Bằng River, Cao Bằng Province, Vietnam as a new species: Pseudobaphia banggiangensis new species. [ABSTRACT FROM AUTHOR]

Two new terrestrial crab species of the family Potamidae, Tiwaripotamon xuanson and T. hamyen, are described from northern Vietnam. Tiwaripotamon xuanson was collected from Xuan Son National Park, Thanh Son district, Phu Tho province, and T. hamyen was found in Binh Xa commune, Ham Yen district, Tuyen Quang province. They can be distinguished from other congeners by distinct carapace characteristics and gonopod 1 structures. [ABSTRACT FROM AUTHOR]

A new freshwater crab species of the family Potamidae is described from the boundaries of northern Vietnam and southern China. Tiwaripotamon pluviosum sp. nov. can be distinguished from other species by a suite of morphological characters, including a relatively flat carapace, relatively less slender legs, and distinct dorsal flaps on the male first gonopods. Molecular data using the mitochondrial cytochrome oxidase subunit I (COI) also supports this species as being new. [ABSTRACT FROM AUTHOR]

A new species of potamid freshwater crab, Indochinamon chuahuong, is described from Ha Noi, northern Vietnam. The new species can be distinguished from all other Indochinamon species by a suite of characters, including a carapace broader than long; an anterolateral margin that is convex and distinctly serrated; longer ambulatory legs than its congeners; and the terminal segment of the male first gonopod being curved outwards, with a very low dorsal flap. [ABSTRACT FROM AUTHOR]

A revision of Vietnamese freshwater gastropods of the family Pachychilidae is presented based on the analysis of morphological characteristics and partial sequences of the mitochondrial genes of 16S rRNA (16S) and cytochrome c oxidase subunit I (COI). We found that in Vietnam two pachychilid genera occur, Brotia and Sulcospira. Of the eight to fifteen species reported by earlier authors, we can only confirm the presence of two species, Sulcospira tonkiniana and S. tourannensis. All further taxonomic names that were previously applied for Vietnamese pachychilids are considered as junior synonyms of these two species or erroneous references to species from other regions of Southeast and South Asia. Additionally, we describe two new species of Brotia, four new species of Sulcospira, and report another undescribed species with uncertain affinities. Patterns of morphological and genetic differentiation of the Vietnamese species and their affinities within the context of pachychilid phylogeny are briefly discussed. [ABSTRACT FROM AUTHOR]