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Freshwater mussels are one of the most diverse groups of freshwater organisms as well as one of the most endangered groups of organisms on Earth. Freshwater mussels have a life history that...

Freshwater mussels provide important functions and services for aquatic ecosystems, but populations of many species have been extirpated. Information on biodiversity plays an important role in the conservation and management of freshwater mussels. The Xin River Basin is a biodiversity hotspot for freshwater mussels in China, with more than 43 species known, but populations of which are decreasing. Here, we quantify the diversity of freshwater mussels in the middle and lower reaches of the Xin River Basin and study the correlation of habitat characteristics and freshwater mussel diversity. Compared to the historical period, the number of species, density, and biomass of freshwater mussels decreased 33%, 83%, and 82% in the current period, respectively. Fifty two percent of recorded species were empty shells, and 14 native freshwater mussels were not found in the study area. Four species are currently listed as vulnerable species using IUCN criteria and their global status. The assemblage structure of freshwater mussels exhibits significant spatial differences, and there was a correlation with substrate and physicochemical parameters. The main tributary of the Xin River with higher freshwater mussel diversity should be established as one large protected area because the nestedness component was the main pattern of beta diversity. These results indicated freshwater mussel diversity was declining rapidly, which can help focus conservation effort for freshwater mussel biodiversity., Freshwater mussels provide important aquatic ecosystem functions and services, but many of their populations are in decline. Here, we systematically quantitative analyze freshwater mussel diversity in the Xinjiang River and explore the correlation of habitat characteristics and freshwater mussel diversity. The results showed that the diversity of freshwater mussels decreased rapidly in the Xinjiang River. Assemblage structure of freshwater mussels exhibits significant spatial differences. The assemblage composition of freshwater mussels was correlated with turbidity, PM, and water temperature. The MT should be established one large protected area because the nestedness component was the main pattern of beta diversity. This study will provide important information for the conservation and management of freshwater mussel biodiversity.

Habitat fragmentation is one of the main threats to biodiversity. Barriers to dispersal caused by anthropogenic habitat alteration may affect phylogeographic patterns in freshwater mussels. Knowledge of the phylogenetic and phylogeographic patterns of unionoids is vital to inform protection of their biodiversity. Here, we assessed influences of dams and their environmental effects on the genetic diversity and population connectivity of a broadly distributed freshwater mussel, Nodularia douglasiae, in Poyang Lake Basin. The results showed high genetic diversity in areas without dams and low genetic diversity in areas with dams. High genetic differentiation and low gene flow were found among the 11 populations. Genetic variation was significantly correlated with dissolved oxygen levels. The observation of low genetic diversity in populations separated by dams indicated that those populations were subjected to genetic erosion and demographic decline because they are disconnected from other populations with higher diversity. High genetic differentiation and low gene flow among the 11 populations could be correlated with anthropogenic habitat alteration. These results indicated that anthropogenic habitat alterations have led to the decline in freshwater mussel diversity. Therefore, we recommend maintaining favourable habitat conditions and connectivity of rivers or lakes, and strengthening study of life histories with host‐test experiments to identify potential host fish species to strengthen the knowledge base underpinning freshwater mussel conservation.

This paper analyses the different phonological strata of first division unrounded finals of the Xiè Rhyme Group （蟹攝），specifically the Xai rhyme and Tài rhyme, in the finals system of proto-Min and explores the distinction between double rhymes in old Jiangdong dialects. Norman (1981) reconstructed five finals for Xai rhyme and Tài rhyme. They are: *əi for Xai 菜咍栽咍來咍 *oi for Xai 袋咍 *ɑi for Tài 帶泰蔡泰蓋泰 *uəi for Xai 改咍 *yəi for Xai 開咍 According to Norman’s reconstruction, there are four finals for the Xai rhyme but there is only one final for the Tài rhyme. Therefore, some issues need to be clarified. To begin with, what is the time sequence of those four forms of Xai? Additionally, three forms are reconstructed by one cognate in proto-Min. It is highly doubtful to regard those forms as a single stratum individually. Furthermore, the double rhymes, Xai and Tài, could be distinct in the Qieyun system but merged in most modern Chinese dialects. However, some southern dialects retain the distinction (refer to Cao et al. 2000, Wang 2004 and Wu 2005). How is the distinction of double rhymes expressed in proto-Min? It is worth examining those questions in depth. The methodology of this paper is the comparative method. We would like to expand Min dialectal material and find more reliable cognates to reexamine Norman’s finals of Xai and Tài. From the perspective of historical development, proto-Min has several different phonological strata. After thoughtful and cautious analysis, those strata could be an important reference for the reconstruction of both Middle Chinese and Old Chinese. An important aim of this paper is to reconstruct the Jiangdong dialect, a southern Chinese dialect used in the Six Dynasties period, using proto-Min and related common dialect systems. In conclusion: 1. both Xai and Tài could be reconstructed as two forms in the finals system of Proto-Min. In brief, *-əi and *-oi are for Xai; *-ɑi and *-ai are for Tài. 2. from a diachronic development viewpoint,the pattern *-oi: *-ai reveals the distinction of Xai and Tài, i.e. double rhyme, in the Six Dynasties Jiangdong dialect. 3. Relatedly, the pattern *-əi: *-ɑi could be traced to differences between the Zhi group （之部） and Jì group （祭部） in Old Chinese.

According to Qièyùn, Tán (覃) and Tán (談) are two distinct rhymes, i.e. double rhyme, in Xián Shè Grade I. From the historical Chinese phonology perspective, the Northern people who spoke the Northern dialect started merging Tán / Tán distinction at early Tang Dynasty but, relatively, the Southern people retained it. In other words, Tán / Tán distinction is an important phonological feature to divide the early Chinese dialects into Northern group and Southern group. Recent researches shows that Tán / Tán distinction still obtain in modern Chinese dialects, such as Wú, Mĭn and Gàn dialects. However, the question ‘if Tán / Tán distinction obtains in modern Xiang dialect’ is under debate until now. This article would like to examine 12 modern Xiang dialects and explore the phenomena and phonological contrast in Xiang dialects. Furthermore, this article also tried to reconstruction the proto forms for Tán / Tán rhymes. This article not only focused on the phonological contrast provided by Qièyùn framework but also noticed the colloquial lexicons, which retained the early distinction. The main conclusions are as follows:1.From the viewpoint of phonological contrast, only one kind of Xiang dialect subcategories, i.e. Lóu-Shào Piàn, obtains Tán / Tán distinction. The distinction has been dropped in Cháng Yì Piàn and Xù Pŭ Piàn.2.From the viewpoint of colloquial lexicon, there are still four lexicons with Tán / Tán distinction. Those lexicons are distributed in modern Xiang dialects more or less. 3. From the viewpoint of historical linguistics, the Tán (覃) rhyme after velar initials could be reconstructed as *-oN and *-oʔ and the Tán (談) rhyme as *ɑN and *ɑʔ after the same initial environment. It shows that Tán / Tán distinction is partially remained in Xiang dialects. The main vowel *-o in *oN and *-oɁ finals tends to vowel breaking and so the reflections of *oN and *oʔ in modern Xiang dialects include -uẽ, -uɛ̃, -ua and -ue etc.

Despite the diversity and economic and ecological value of freshwater mussels, relatively little is known about their biology (especially for species outside of Europe and North America). Solenaiacarinata is an endangered freshwater mussel, is endemic to China and is now only distributed in Poyang Lake basin. However, its conservation status is not clear. Thus, for this study, surveys were conducted at 41 sites along the lower reaches of the Ganjiang River to study the conservation status of S.carinatus. The results showed that S.carinata had a restricted distribution and extremely low density. In addition, the habitat sediments where S.carinata was located were mainly composed of silt (particle size S.carinata was correlated to dissolved oxygen, temperature, turbidity and chlorophyll-a. Microsatellite analysis showed that S.carinata had a low genetic diversity (mean HO: 0.419; mean HE: 0.484; mean PIC: 0.430). At the same time, we firstly report the glochidia of S.carinata and describe its morphological characteristic. Surprisingly, its reproduction period and morphological characteristics were different from that of others freshwater mussels. Therefore, this study clarified the resource conditions, endangered status and threat factors for S.carinata and it provided a theoretical basis for the conservation and management of its resources.

As the endemic species of China, Aculamprotula scripta is one of the most imperilled freshwater mussels. In this study, the complete maternal mitochondrial genome of A. scripta was firstly determined. The genome (15688 bp) had a typical structure of invertebrate mtDNA. It contained 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and 1 novel gender-specific ORF. The nucleotide composition of the genome had a base preference, with the overall A + T content of 62.91%. The phylogenetic analysis revealed that A. scripta belonged to Unioninae, and was closely related to A. tientsinensis and A. coreana.

Freshwater mussels have suffered a severe decline during the last century. Accurate description and identification of species have been an arduous and important task for the conservation of this group. Recently, with the promotion of molecular technology, especially mtDNA, many morphological species have been merged. In the genus Lamprotula, L. caveata, L. cornuumlunae and L. leaii are recognized as valid species. The complete mitogenome of. L. cornuumlunae was firstly sequenced in this study. By comparing mitochondrial genomics and phylogenetic analysis, the results showed that mtDNA cannot distinguish between L. caveata and L. cornuumlunae. We hypothesized that the deficiencies of mtDNA in species delimitation was caused by very recent speciation. Time-calibrated multilocus divergence time estimation revealed that L. caveata and L. cornuumlunae recently diverged in the Neogene Pliocene. This study presents the potential problems of relying on mtDNA sequences for delimiting recently diverged species. We emphasis that mtDNA cannot be used solely or dominantly to understand biodiversity. Instead, it is indeed an effective tool, combined with more data, such as shell morphology, reproductive characters and biogeography, to integrate species concepts.

The Yangtze River Basin (Changjiang Basin) hosts one of the most diverse freshwater mussel assemblages on Earth. However, due to human activities this fauna is dramatically imperiled in this region, highlighting the need for urgent conservation measures. To better protect and conserve these taxa, it is crucial to understand the main drivers that control the diversity patterns, as well as the anthropogenic influence on these patterns. Here, we estimated distinct diversity metrics (i.e. species richness and alpha, gamma, and beta diversity) to analyze the spatial freshwater mussel diversity changes across 16 tributaries and lakes from the middle and lower Yangtze River Basin, in two periods: past 1962–2012 and present. For the past, mussel records were compiled from previous studies, for the present, we surveyed 565 sites for freshwater mussel presence and abundance within the 16 selected areas. We also assessed several climatic and geographical parameters to try to identify the main factors that modulate species composition across the study area. We show that from the historical to the present periods, species diversity experienced a significant decrease, registering, per river/lake, an average of 5.4 extirpations of species native to China and 3.9 of the Yangtze River Basin endemics. The gamma diversity of the whole study area and the alpha diversity of each of the studied rivers and lakes have also decreased during this period. The beta diversity values indicated a significant trend towards taxonomic homogenization over the last decades. Poyang and Dongting Lakes should be considered for protection given due to their high diversity and species loss given that nestedness in these lakes represented the main component of beta diversity.

Two Unionida (freshwater mussel) families are present in the Northern Hemisphere; the Margaritiferidae, representing the most threatened of unionid families, and the Unionidae, which include several genera of unresolved taxonomic placement. The recent reassignment of the poorly studied Lamprotula rochechouartii from the Unionidae to the Margaritiferidae motivated a new search for other potential species of margaritiferids from members of Gibbosula and Lamprotula. Based on molecular and morphological analyses conducted on newly collected specimens from Vietnam, we here assign Gibbosula crassa to the Margaritiferidae. Additionally, we reanalyzed all diagnostic characteristics of the Margaritiferidae and examined museum specimens of Lamprotula and Gibbosula. As a result, two additional species are also moved to the Margaritiferidae, i.e. Gibbosula confragosa and Gibbosula polysticta. We performed a robust five marker phylogeny with all available margaritiferid species and discuss the taxonomy within the family. The present phylogeny reveals the division of Margaritiferidae into four ancient clades with distinct morphological, biogeographical and ecological characteristics that justify the division of the Margaritiferidae into two subfamilies (Gibbosulinae and Margaritiferinae) and four genera (Gibbosula, Cumberlandia, Margaritifera, and Pseudunio). The systematics of the Margaritiferidae family is redefined as well as their distribution, potential origin and main biogeographic patterns., This work was supported by FCT – Foundation for Science and Technology, Project 3599 – Promote the Scientific Production and Technological Development and Thematic 3599-PPCDT by FEDER as part of the project FRESHCO: Multiple implications of invasive species on Freshwater Mussel co-extinction processes (contract: PTDC/ AGRFOR/1627/2014). FCT also supported MLL (SFRH/BD/115728/2016) and EF (SFRH/BPD/108445/2015). The Russian Ministry of Education and Science (project no. 6.2343.2017/4.6), the Federal Agency for Scientific Organizations (project no. 0409-2015-0143), the Presidium of the Russian Academy of Sciences (scientific program no. 52), and the Russian Foundation for Basic Research, RFBR (project no. 17-45-290066) supported INB, MYG, AVK, and IVV. The Nagao Natural Environment Foundation (NEF) supported for VTD research project “The study of Unionoida biodiversity and conservation status in Bang and Ky Cung River basins in Northeast Vietnam”.

Stylommatophora is a main clade of Gastropoda that encompasses approximately 112 gastropod families and may exceed a total of 30,000 species. Twenty-four complete stylommatophoran mitogenomes have been sequenced to date, yet our understanding of mitochondrial evolution in stylommatophorans is still in its infancy. To further expand the set of available mitogenomes, we sequenced the mitogenome of Meghimatium bilineatum (Arionoidea: Philomycidae), a widespread land slug in East Asia. This is the first report on a mitogenome of the superfamily Arionoidea, and indeed on a terrestrial slug. The mitogenome of Meghimatium bilineatum comprises 13,972 bp and exhibits a novel, highly distinctive gene arrangement among the Stylommatophora. Phylogenetic reconstructions based on the sequences of all protein-coding genes consistently recovered Meghimatium bilineatum as sister-group of the Succineidae. A phylogenetic reconstruction based on gene order, however, suggested a highly divergent tree topology, which is less credible when taking into account prior knowledge of stylommatophoran relationships. Our CREx (Common interval Rearrangement Explorer) analysis suggested that three successive events of tandem duplication random loss (TDRL) best explain the evolutionary process of gene order rearrangement in Meghimatium bilineatum from an ancestral stylommatophoran mitogenome. The present example offers new insights into the mechanisms of mitogenome rearrangements in gastropods at large and into the usefulness of mitogenomic gene order as a phylogenetic marker.

The middle and lower portions of the Yangtze River basin is the most species-rich region for freshwater mussels in Asia. The management and conservation of the taxa in this region has been greatly hampered by the lack of a well-developed phylogeny and species-level taxonomic framework. In this study, we tested the utility of two mitochondrial genes commonly used as DNA barcodes: the first subunit of the cytochrome oxidase c gene (COI) and the first subunit of the NADH dehydrogenase gene (ND1) for 34 putative species representing 15 genera, and also generated phylogenetic hypotheses for Chinese unionids based on the combined dataset of the two mitochondrial genes. The results showed that both loci performed well as barcodes for species identification, but the ND1 sequences provided better resolution when compared to COI. Based on the two-locus dataset, Bayesian Inference (BI) and Maximum Likelihood (ML) phylogenetic analyses indicated 3 of the 15 genera of Chinese freshwater mussels examined were polyphyletic. Additionally, the analyses placed the 15 genera into 3 subfamilies: Unioninae (Aculamprotula, Cuneopsis, Nodularia and Schistodesmus), Gonideninae (Lamprotula, Solenaia and Ptychorhychus) and Anodontinae (Cristaria, Arconaia, Acuticosta, Lanceolaria, Anemina and Sinoanodonta). Our results contradict previous taxonomic classification that placed the genera Arconaia, Acuticosta and Lanceolaria in the Unioninae. This study represents one of the first attempts to develop a molecular phylogenetic framework for the Chinese members of the Unionidae and will provide a basis for future research on the evolution, ecology, and conservation of Chinese freshwater mussels.

Radix plicatula is broadly distributed in China, as well as Russia. It is one of the intermediate hosts of Fasciola species which leads to the spread of fascioliasis. Here, we first described the complete mitochondrial genome of R. plicatula. The mitogenome is 13,751 bp in length, containing 13 protein-coding genes, 22 tRNA genes, and 2 rRNA genes. The contents of each base are 30.7% A, 39.6% T, 15.7% G, and 13.9% C. The sequence is AT rich (70.3%). Mitochondrial phylogenomic analysis showed that R. plicatula is close to R. auricularia.

Biomphalaria straminea is an invasive species in China and is one of the intermediate hosts of Schistosoma mansoni which results in the spread of schistosomiasis. Herein, we firstly report the comp...

This paper explores the diachronic change of kʰi3 (乞) in Modern Min dialects from the viewpoint of historical grammar. k h i3 is a polysemy in Min dialect and has both content meaning and functional usage. According to the Chinese written documentation, kʰi3 had two opposite meanings, 'to beg' vs. 'to give', and distinguished those two meanings by tonal inflection: 'to beg' had *-t coda and 'to give' had *-s coda. This paper combines the early Min written documentation and field material of modern Min dialect to investigate the diachronic change included phonology, lexicon and grammaticalization of k h i3 in Min dialect. This paper presents three main conclusions as follows:1.Phonological perspective: the cognate of kʰi3 in proto Min could be reconstructed as *kʰɨt7. Proto Min received the form with *-t coda (Ru Sheng)and dropped the *-s form (Qu Sheng).2.Lexical perspective: Min dialect has not only ‘to beg’ meaning but also ‘to give’.3.Grammatical perspective: the grammaticalization path of kʰi3 in Min dialect is [‘to give’ > ‘to cause’ > passive marker]. (This article is in Chinese.)提要本文從歷史語法的角度，探討「乞」在現代閩語方言中的演變，說明「乞」在閩語中具有的功能，包括實詞語義及功能詞用法，並嘗試從方言比較的角度建構「乞」在閩語語法史上的語法演變。根據漢語歷史文獻，「乞」有乞求義跟給予義兩個方向不同的動詞用法，並透過四聲別義的手段來區別。從現代閩語方言看來，閩東方言及局部閩南方言使用「乞」作為被動標記。本文結合早期閩語書面材料及實際調查所得的語料，探究「乞」在閩語中的音韻、詞彙及語法演變。本文的結論如下：1. 音韻方面，「乞」在共同閩語中的語音形式為*kʰɨt7，只有入聲而沒有去聲。2. 詞彙方面，閩語的「乞」同時存在乞求義與給予義兩種實詞用法。3. 就語法演變而言，閩語被動標記「乞」的虛化途徑是：給予義→容讓義→被動標記。

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.

According to this author’s fieldwork in Pei Pi Village（北壁鄉），Xia Pu County（霞浦縣），a very interesting finding is that unlike most Chinese dialects, the cognate 飯‘puŋ6’ is not used to mean “steamed rice” but to mean “breakfast”. The word to indicate “steamed rice” is a rare disyllable “maŋ2 nau5” among Eastern Min dialects. This phenomenon is worthy to be looked into by increasing review of dialect materials and expanding the comparative scope. Through correspondence with ancient Chinese phonological system, this paper aims to demonstrate that the etyma of the disyllable “maŋ2 nau5” are 暝 and 晝 respectively. The compound “maŋ2 nau5” consisted of two elements: the former (which indicates “dinner”) is “maŋ2”, and the latter “nau5” denoted “lunch.” It is obvious that the lexical replacement occurred in Xia Pu dialect. From the lexical shift point of view, the innovation of the replacement is induced by the semantic confusion between “puŋ6”[飯] and “tsa3”[早]. The process of the replacement could be reconstructed as follows: Further, the etymon of “steamed rice” in several north Eastern Min dialects seems not to be explained reasonably until now, for instance, Fu An “maŋ5”, Zhe Reng “maŋ5”, Shou Ning “maŋ5”, Zhou Ning “maŋ5”. The disyllable “maŋ2 nau5” in Xia Pu may bring the puzzle into light. In view of historical comparison, I have every reason to speculate that “maŋ5” in north Eastern Min dialects could be traced back to the primitive form “maŋ2 nau5”. The phonological strategy is syllable contraction.

Aculamprotula tientsinensis is a rare and endemic species of freshwater mussel in China. This study firstly determined the complete F-type mitochondrial genome of A. tientsinensis. The circle genome (15 695 bp) comprises 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, 1 FORF gene. Except for cob, nad5 and nad6, the remaining protein-coding genes initiate with the orthodox start codon (ATG, ATA, ATT). There are 26 non-coding regions in the mitogenome of A. tientsinensis, ranging in size from 1 to 229 bp. The base composition of the genome is A (37.83%), G (12.69%), T (25.43%) and C (24.06%). Gene order is identical to other female species of Unionidae but for Gonideinae. The phylogenetic analyses of Unionidae indicate that A. tientsinensis is closely related to A. tortuosa and A. coreana, which belong to Unioninae. The complete mitogenome can deepen comparative and evolutionary genomics of Unionidae and be more comprehensive to parse the genetic relationship between the species and the ownership beyond species.