A quadrannulate species, Orobdella ganini sp. nov., is described from the Lazovsky Nature Reserve in Primorsky Krai, the Southern Russian Far East, Russia. Morphological features of O. ghilarovi ...Nakano & Prozorova, 2019 from the reserve are also provided leading to an amendment of the species diagnosis. Maximum likelihood and Bayesian inference phylogenetic analyses, which were performed using nuclear 18S rRNA, 28S rRNA, and histone H3, and mitochondrial cytochrome c oxidase subunit I, tRNACys, tRNAMet, 12S rRNA, tRNAVal, 16S rRNA, tRNALeu and NADH dehydrogenase subunit 1 markers, show that O. ganini sp. nov., O. ghilarovi and two species endemic to Hokkaido, Japan form a clade, with the new species sister to a lineage composed of the two Japanese species. A partial cytochrome c oxidase subunit I sequence obtained from a cocoon found in the Lazovsky Nature Reserve reveals that Orobdella leeches deposit cocoons somewhat similar to those deposited by terrestrial blood-sucking leeches of Haemadipsidae.
The diversification of phenotypes and species has been a major concern in evolutionary biology. Both resource competition and predator–prey interactions have been suggested as mechanisms that drive ...phenotypic divergence and speciation, but the latter has attracted much less attention than the former. The Karaftohelix land snails in Northeast Asia provide an excellent model to investigate the effects of competition and predation on the divergence process. This is because (1) all species—especially Karaftohelix editha and Karaftohelix gainesi in northern Japan—are closely related and sometimes indistinguishable by genital morphologies and neutral nuclear and mitochondrial DNA markers, despite the distinct phenotypes among species; (2) two different anti‐predatory strategies (i.e., passive and active defenses) are observed for each species in this group; and (3) multiple species have generally overlapping distributions and were often observed at exactly the same time and place. In this study, we conducted quantitative quadrat surveys and carbon/nitrogen stable isotope analyses to compare the microhabitat and trophic niches among Karaftohelix land snails and estimated the cause of adaptive radiation in this taxon. All the results indicated that the differences in microhabitats and trophic niches among Karaftohelix land snails—especially between the most closely related sister species, K. editha and K. gainesi in northern Japan—were too small to promote the adaptive radiation in this group. Therefore, it is difficult to explain the extreme divergence of phenotypes and species among Karaftohelix land snails in Northeast Asia based on environmental adaptation through resource competition and/or reproductive interference.
The quantitative quadrat surveys and carbon/nitrogen stable isotope analyses were conducted to compare the microhabitat and trophic niches among Karaftohelix land snails in Northeast Asia. All the results indicated that the differences in microhabitats and trophic niches among Karaftohelix land snails‐especially between the most closely related sister species, K. editha and K. gainesi in northern Japan‐were too small to promote the adaptive radiation in this group. Therefore, it is difficult to explain the extreme divergence of phenotypes and species among Karaftohelix land snails based on environmental adaptation through resource competition and/or reproductive interference.
Maritime ecosystems in Vietnam such as mangroves and mud flats are characterized by high biodiversity. However, elements of its biodiversity remain unclear and highly threatened. In this context, the ...assessment of rare species is a starting point to develop effective strategies for the conservation of entire ecosystems. In this paper, we report upon cryptic amphibolid gastropods in Vietnamese mangrove forests from the Mekong Delta. The snail fauna in the mangrove forests was previously known from published literature and three museum specimens as three amphibolid species, 'Amphibola' burmana, A. quadrasi, Salinator fragilis and 'S.' quadrasi. We investigated the identities of such snails using molecular and morphological methods. The amphibolids found in this survey were identified to belong to the genus Naranjia, new for Vietnam fauna. In addition, our phylogenetic analyses suggested that the Vietnamese amphibolids were the same species as Naranjia sp. reported from Thailand, and the amphibolids have both genetic and morphological polymorphisms within the population. These findings add to the great biodiversity of Vietnamese mangrove forests and mudflats.
Endemic organisms of ancient lakes have been studied as models to understand processes of speciation and adaptive radiation. However, it remains unclear how ancient lakes play roles in genetic and ...phenotypic diversity of freshwater mollusks. In the present study, we focus on viviparid freshwater snails in the ancient lakes of East and Southeast Asia (Japan and China) to address this question. Using molecular phylogenetic analyses based on mitochondrial (COI, 16S) and nuclear genes (18S, 28S, H3), we show that patterns of species diversification in viviparid lineages. Colonization to ancient lakes occurred independently in China and Japan at least four times, with subsequent diversification into more than two species within each lake group. Morphological analyses of fossil related viviparids suggest parallel phenotypic evolution occurred in the different lakes and ages. Each lake contained a single lineage which was phenotypically diversified relative to those from other sites. Using genome‐wide SNPs obtained by MIG‐seq, we also examined the genetic structure of three Japanese viviparids, including two endemic species of ancient Lake Biwa. The results suggest that these two species diversified from the population of the third species living in wetlands surrounding the lake. These findings suggest that rapid diversification of lineages and phenotypic divergence can occur in ancient lakes compared to other habitats. Formation of large lakes probably promotes speciation and phenotypic divergence as a result of adaptation into different microhabitats. High numbers of ancient lakes could be a driver of species diversity in Asian viviparid snails.
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•Phylogenetic analysis reveals a high lineage diversity of Sphaeridae in Japan.•Analyses suggest Japanese Sphaeriidae consist of at least 18 delimitated lineages.•Many lineages have ...been observed only in Japan.•Sphaeriid diversity may result from both ancient colonisations and recent dispersals.
Revealing the species and lineage diversity of a taxon is important for many biological studies of wildlife. In recent decades, DNA-based approaches have been widely utilised to elucidate the diversity of taxa, especially those that are difficult to distinguish based on morphological traits. This study focused on freshwater clams (Sphaeriidae) in Japan, a biodiversity hotspot of freshwater molluscs. Molecular phylogenetic approaches, including divergence time estimation, species delimitation, rarefaction, and biogeographic area estimation, were used to reveal the nature of the species diversity and its formation process, which are largely unknown. Our delimitation and rarefaction analyses suggest that Japanese sphaeriid clams consist of at least 18 delimitated lineages. This lineage diversity is relatively high compared to other Japanese freshwater molluscs, and in addition, the majority of the Japanese lineage appears to have high endemicity despite the possibility of long-distance dispersal in sphaeriid clams. Our biogeographical analyses suggest that this diversity may be due to the combination of colonisation, during the period when Japan was connected to the continent, and the relatively recent dispersal. Our results highlight the overlooked biodiversity of Japan and provide a basis for further Japanese sphaeriid research, including conservation perspectives.
The taxonomic position and phylogenetic affinities of the endemic North Asian genus Kolhymamnicola Starobogatov and Budnikova, 1976 (Gastropoda: Amnicolidae) remain unknown. To resolve this, we ...studied key morpho-anatomical characteristics of Kolhymamnicola snails and performed a molecular phylogenetic analysis based on sequences of COI mtDNA, 16S rRNA, and 18S rRNA genes. In terms of protoconch microsculpture, operculum, radular teeth, and gill complex morphology, Kolhymamnicola snails do not differ significantly from the North American genera Amnicola Gould and Haldeman, 1840 and Taylorconcha Hershler et al., 1994, and the European genus Marstoniopsis van Regteren Altena 1936. The bifid penis found in Kolhymamnicola is similar to that in the genus Marstoniopsis. The female reproductive anatomy has some features shared by Kolhymamnicola and Taylorconcha (absence of bursa copulatrix, single seminal receptacle in rs2′ position, and ventral channel). The molecular analysis has revealed Taylorconcha as the closest relative to Kolhymamnicola; the COI-based genetic distance between them amounted to 0.113. We discuss the possible time of divergence of these two genera, as well as of European Marstoniopsis and the Baikal Lake endemic family Baicaliidae. The last common ancestor of these groups was widely distributed in Miocene–Pliocene in the Holarctic waterbodies. Recent Kolhymamnicola snails are distributed in Northern Asia, including lakes of the Baikal rift zone. We rank the Baicaliidae as a family rather than a subfamily of Amnicolidae based on their distinct, unique morpho-anatomical characteristics and highly supported separate position on the molecular tree. The tribe Erhaiini Davis and Kuo, 1985 is elevated to the rank of the family, with 3–4 recent genera included. The family Palaeobaicaliidae Sitnikova et Vinarski fam. nov. is established to embrace the Cretaceous North Asian gastropods conchologically similar to the recent Baicaliidae and Pyrgulidae.
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.
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.
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.
Persistent organic pollutants (POPs) are distributed in the environment worldwide. These pollutants are found ubiquitously in the environment, including commercially valuable aquatic organisms. ...Vietnam is one of the world’s largest exporters of seafood, including bivalves. At the same time, comprehensive monitoring studies of aquatic ecosystems in Vietnam are insufficient and not coordinated and are mainly aimed at detecting heavy metals. We studied concentrations of organochlorine pesticides (OCPs (DDT, HCH)) and polychlorinated biphenyls (PCBs) in bivalves of four genera (
Corbicula
,
Geloina
,
Ensidens
,
Scabies
) collected from the Mekong Delta and Saigon–Dong Nai River Delta as well as purchased freshly caught at local markets in the spring of 2017 and 2018 before the rainy season. The studied watercourses and waterbodies can be arranged in the following order of increasing pollution: Lake Binh Thien – Hau River – Tien River – Ba Lai River – Saigon–Dong Nai River. The surveyed areas of mangrove ecosystems in the provinces of Kien Giang and Bac Lieu cannot be included in this order, since they are inhabited by mangrove clams
Geloina
sp. of the family Cyrenidae, which are bivalves with narrow specialization. Currently, the major factors responsible for the OCP pollution in South Vietnam may be agricultural activities and industrial sectors which disregard the recommendations and bans on the use of these hazardous compounds, along with the persisting unfavorable background in the form of DDE being a consequence of the wide application of DDT until 1995.
Lake Baikal is the deepest, oldest and most speciose ancient lake in the world. The lake is characterized by high levels of molluscan species richness and endemicity, including the limpet family ...Acroloxidae with 25 endemic species. Members of this group generally inhabit the littoral zone, but have been recently found in the abyssal zone at hydrothermal vents and oil-seeps. Here, we use mitochondrial and nuclear data to provide a first molecular phylogeny of the Lake Baikal limpet radiation, and to date the beginning of intra-lacustrine diversification. Divergence time estimates suggest a considerably younger age for the species flock compared with lake age estimates, and the beginning of extensive diversification is possibly related to rapid deepening and cooling during rifting. Phylogenetic relationships and divergence time estimates do not clearly indicate when exactly the abyssal was colonized but suggest a timeframe coincident with the formation of the abyssal in the northern basin (Middle to Late Pleistocene).
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