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A re-examination of the holotype of the type species Halysestheria biformis Zhang & Chen in Zhang et al., 1976 has revealed new characters that were overlooked in the original description. And a taxonomic research was carried out on the clam shrimp collected from the Upper Cretaceous Nenjiang Formation in the central Dayangshu Basin in Ganhe, Oroqen Autonomous Banner, eastern Inner Mongolia. The discovery of Halysestheria biformis indicates the fossil bearing horizon belongs to the upper Santonian First Member of the Nenjiang Formation.

We describe aggregative microconchid (Lophophorata) tubes from the uppermost Permian (upper Changhsingian) and Lower Triassic (Olenekian) lacustrine and fluvial strata of the Tunguska and Kuznetsk basins and the southern Cis-Urals, Russia. These attach to clam shrimp carapaces, bivalve shells, terrestrial plant fragments and a horseshoe crab head shield, and also form their own monospecific agglomerations. Planispiral tubes of a wide size range (0.1–2.5 mm) create dense settlements on these firm substrates, which likely comprise multiple generations of the same species. These finds confirm that this extinct lophophorate group was inhabiting non-marine continental basins during latest Permian and earliest Triassic time, when they were major suspension feeders in such limnic ecosystems. Microconchids dispersed extensively and rapidly in the aftermath of the Permian–Triassic mass extinction into both marine and continental basins at low and moderately high latitudes, which were notably different in salinity, temperature, depth and redox conditions. This confirms that small lightly calcified microconchids were a genuine disaster eurytopic group, whose expansion may have been promoted by low predator pressure and low competition for substrate.

Clam shrimp (Spinicaudata) are worldwide distributed branchiopod crustaceans specialised in ephemeral freshwater habitats. The Carboniferous is an important period for the early evolution and diversification of clam shrimp. Compared with the rare and geographically confined fossil record of the Devonian, clam shrimp in the Carboniferous have a much wider geographical distribution and higher biodiversity. Over 20 genera of clam shrimp have been recorded in the Carboniferous all over the world, but they are sparse in China. To date, five records of Carboniferous clam shrimp have been reported from China (Pruvost, 1927; Zhang et al., 1976; Wang, 1987; Zheng et al., 1988; Liu & Fan, 1995; Liao et al., 2019). Among them, four species Lioestheria? mathieui Pruvost, 1927, Protomonocarina huixianensis Wang, 1987, Retrofractus lingyuanensis Liu & Fan, 1995, and Pemphilimnadiopsis cheni Liao, Shen & Huang, 2019, are found in the Pennsylvanian Benxi Formation in North China (Pruvost, 1927; Zhang et al., 1976; Wang, 1987; Liu & Fan, 1995; Liao et al., 2019).

A re-examination of the metatype of the type species Polygrapta chatangensis has revealed new characters that were overlooked in the original description and it is determined here that Polygrapta should be maintained as a genus separate from Pseudestheria.

Vernal pools are unique in their isolation and the strong selection acting on their resident species. Vernal pool clam shrimp (Eulimnadia texana) are a promising model due to ease of culturing, short generation time, small genomes, and obligate desiccated diapaused eggs. Clam shrimp are also androdioecious (sexes include males and hermaphrodites), and here we use population-scaled recombination rates to support the hypothesis that the heterogametic sex is recombination free in these shrimp. We collected short-read sequence data from pooled samples from different vernal pools to gain insights into local adaptation. We identify genomic regions in which some populations have allele frequencies that differ significantly from the metapopulation. BayPass (Gautier M. 2015. Genome-wide scan for adaptive divergence and association with population-specific covariates. Genetics 201(4):1555–1579.) detected 19 such genomic regions showing an excess of population subdivision. These regions on average are 550 bp in size and had 2.5 genes within 5 kb of them. Genes located near these regions are involved in Malpighian tubule function and osmoregulation, an essential function in vernal pools. It is likely that salinity profiles vary between pools and over time, and variants at these genes are adapted to local salinity conditions.

Diet has been linked to lifespan in a broad range of animals. In particular, pronounced caloric restriction has been associated with increased longevity. Herein, the relationship of feeding environment and longevity is examined experimentally using Spinicaudatan crustaceans (“clam shrimp”) from the geographically widespread genus Eulimnadia. Two projects examine the effects of food differences on longevity, one comparing food environment early vs later in life and one comparing the effects of dietary restriction on longevity, growth, and reproduction. In the former, dietary restriction increased longevity, but only when diets were reduced later in life. A closer examination of the effects of dietary restriction in the second experiment did not find the expected trade-off of increased longevity and reduced reproductive output in the lowest-food treatment, but instead found an overall increase in both longevity and egg production on the low compared to the high food diet. Finally, a detailed analysis of the relationship of size (carapace length) with egg production was presented. This relationship could serve to obtain a rough estimate of reproductive output potential of fossil clam shrimps, of which typically only the carapace size can be assessed.

Spinicaudatan clam shrimp are a widespread and diverse group of branchiopod crustaceans, yet few mitochondrial genomes have been published for this taxonomic group. Here, we present the mitogenome ...

The Triglypta–Qaidamestheria clam shrimp assemblage, widely known from the non-marine Jurassic deposits in northern China, is important for biostratigraphic correlation of the fossil bearing strata. QaidamestheriaWang, 1983, an essential component of the assemblage, was originally described from the upmost oil shale member of the Dameigou Formation at the northern margin of the Qaidam Basin, northwest China. Though the original description of the genus Qaidamestheria was based on SEM microscopy, the published pictures of the type specimens are unclear, and the type specimens were lost. We collected new specimens of the type species Qaidamestheria dameigouensisWang, 1983 from the 7th unit of the Dameigou Formation in the Dameigou section, where the holotype of the species was originally collected. The examination of the specimens under SEM has revealed three critical taxonomic features for the genus: the fine reticulation (mesh diameter 7–18 µm) on the larval valve and several adjacent growth bands; the transitional (reticulated-punctate) ornamentation on the middle–ventral part of the carapace; and linearly arranged puncta appearing only on growth bands near the antero-ventral margin of the carapace, puncta never clustered.

Clam shrimps (Spinicaudata) are a widespread and diverse crustacean group that frequent temporary aquatic habitats, but few complete mitochondrial genomes have been published for this group. Here, ...

The crustacean fauna of the Insect Bed (late Eocene), Isle of Wight is reviewed. The fauna comprises the branchiopod Branchipodites vectensis Woodward, 1879, ostracod Potamocypris brodiei Jones and Sherborn, 1889, and isopod Eosphaeroma margarum (Desmarest, 1822). In addition a new clam shrimp (Crustacea: Diplostraca: Spinicaudata) is described and named Paraleptestheria mitchelli sp. nov. This is the first record of the genus outside China and the first 'conchostracan' to be described from the European Cenozoic. Fil: Gallego, Oscar Florencio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina Fil: Yan Bin, Shen. Chinese Academy of Sciences; China Fil: Jarzembowski, Ed. Natural History Museum; Reino Unido. Chinese Academy of Sciences; China Fil: Slipper, Ian J.. University of Greenwich; Reino Unido Fil: Self, Angela. Natural History Museum; Reino Unido Fil: Monferran, Mateo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina

The palaeoecology of Spinicaudata, the dominant group of benthic invertebrates in many pre-Cenozoic freshwater environments, remains poorly understood. In analogy with extant taxa, it has been oversimplified and often reduced to shallow, temporary environments characterized by few trophic levels, implying ecological stasis from the Devonian to the Recent. We excavated 43 horizons of the Lower Cretaceous Yixian Formation (Anjiagou and Hengdaozi beds) to evaluate whether spinicaudatan ecology can be simplified to such an extent. Sedimentological evidence suggests general perennial conditions during the excavated lake interval. Based on 33226 specimen counts, we identified three arthropod-dominated macrobenthic associations and two assemblages. Response curves indicate that the spinicaudatan Eosestheria middendorfii was exceptionally tolerant to environmental gradients, followed, in decreasing order, by mayfly larvae, water boatmen and oligochaetes. Many spinicaudatan-yielding layers represent death after reproductive senescence rather than mass-mortality events. Spinicaudatan size varies significantly according to faunal association. A forward stepwise regression model suggests that growth responded to population density and diversity: lower densities and higher diversities triggered fast growth, and vice versa. The proposed strong density effect on carapace size has been corroborated by rearing experiments: as for E.middendorfii, natural log regression provided the best fit for the two extant species Eulimnadia texana and Eocyzicus argillaquus. Hence, E.middendorfii was a tolerant and morphologically variable species adapted to perennial waters and the frequent presence of higher trophic levels. Although there are rare records of extant taxa co-occurring with fish, the described Early Cretaceous environment is commonly not inhabited by extant Spinicaudata.

Clam shrimps are large bivalved branchiopod crustacean. They first occurred in the Devonian, and flourished during the Mesozoic in Asia. Fossil clam shrimps play an important role in the subdivision and correlation of non-marine fossil-bearing strata. The phosphatized carapaces or carapace external/internal moulds are the main objects for taxonomical studies. The delicate ornament and the ontogenetically developing morphological patterns on the growth bands of carapaces are the main fossil taxonomic criteria. While modern clam shrimp taxonomy is based on soft body morphological features and molecular data, which could not be found in the fossil records. This makes it difficult to discuss the fossil and modern clam shrimp phylogenetic relationship. Nowadays scanning electron microscopes are widely available, and can play an important role in investigating clam shrimp carapace morphology which could be common language to integrate fossil and modern taxonomy.

We present the first records of Leptestheria brevirostris since its discovery in Namibia by Barnard in 1924. Our records come from Botswana and South Africa, and present significant range extensions. We redescribe L. brevirostris according to modern standards and present the first description of the male. We also discovered that L. brevirostris is likely a rock pool specialist, specific to sandstone and gneiss outcrops; this is the first record of a rock pool specialist clam shrimp from Africa and the second rock pool specialist described for Leptestheriidae. Finally, we depict and discuss the validity and usefulness of diagnostic characters for Leptestheria species in southern Africa, especially the usefulness of carapace interval ornamentation.

Large branchiopods has been distributed in temporary waters around the world, but the knowledge about these organisms in Colombia is poorly known, especially leptesteriids, we report a new record of the Clam Shrimp Leptestheria venezuelica Daday, 1923 from the north of Colombia., Los grandes branquiopodos se encuentran distribuidos en aguas temporales de todo el mundo, pero el conocimiento de estos en Colombia es poco sobre todo de los leptesteridos, en este trabajo presentamos un nuevo reporte del camaron almeja Leptestheria venezuelica Daday, 1923 para el norte de Colombia.

We describe four upper Lower Triassic to lower Middle Triassic clam shrimp-bearing intervals from Mallorca, which include the clam shrimp species Hornestheria sp. aff. Hornestheria sollingensis and several other forms of carapace valve morphology: Hornestheria? Morphotype 1, Hornestheria? Morphotype 2, and other undetermined carapace valves. All of this material was obtained from red-bed units cropping out in the Serra de Tramuntana mountains of Mallorca (western Mediterranean). Except for a few morphologically similar carapace valves of Middle Triassic age from China, Hornestheria is known only from the type locality of its type species, Hornestheria sollingensis Kozur et Lepper, in the Solling Formation (Middle Buntsandstein Subgroup) in the German part of the Central European Basin. According to its original definition, the larval carapace valve of Hornestheria Kozur et Lepper is characterized by a radial sculpture, but this characteristic apparently is only variably developed. Due to both a limited number of previously known occurrences of Hornestheria and its poorly known carapace valve morphology, open nomenclature is applied to the taxonomy herein. The studied specimens were freshly collected from outcrop sections composed of greyish-green to greyish-red laminated claystones and siltstones that accumulated in a fluvial facies. The clam shrimp specimens are accompanied by remains of insects and fishes, invertebrate and tetrapod ichnofossils, and micro-/macroplant remains, all of which either have been described by previous workers or are currently part of a separate study.

The large branchiopods (fairy shrimp, tadpole shrimp, and clam shrimp) are flagship animals for the conservation of seasonal wetlands and salt lakes. These animals live in seasonally astatic aquatic habitats on all continents and many islands. However, these habitats generally occur on level open land, which tends to be desirable for development or other land conversion types. Although fairy shrimp biodiversity is reasonably understood, the biodiversity of the other branchiopod groups is limited due to morphological plasticity, numerous cryptic taxa, and confounding genetic systems. Furthermore, most taxa are known from only their type locality. While many specific anthropogenic threats are clear, the high number of narrow range endemics suggests that many taxa may become extinct due to stochastic effects.

International audience; Special issue (articles 32-46) communicated by Thomas A. Hegna and D. Christopher Rogers Spinicaudata (spiny clam shrimp) is a taxon of Branchiopoda occurring since the Devonian and today it occurs nearly globally in temporary water bodies. We present the most species-rich phylogenetic analyses of this taxon based on four molecular loci: COI, 16S rRNA, EF1α and 28S rRNA. Our results support previous findings that Cyzicidae sensu lato is paraphyletic. To render Cyzicidae monophyletic we establish a fourth extant spinicaudatan family to accommodate Eocyzicus. Within Cyzicidae, none of the genera Cyzicus, Caenestheria or Caenestheriella are monophyletic, and the morphological characters used to define these genera (condyle length and rostrum shape) are not associated with well-delimited clades within Cyzicidae. There is insufficient resolution to elucidate the relationships within Leptestheriidae. However, there is sufficient evidence to show that the leptestheriid genera Eoleptestheria and Leptestheria are non-monophyletic, and there is no support for the genus Leptestheriella. Molecular clock analyses suggest that the wide geographic distribution of many spinicaudatan taxa across multiple continents is largely based on vicariance associated with the break-up of Pangea and Gondwana. Trans-oceanic dispersal has occurred in some taxa (e.g., Eulimnadia and within Leptestheriidae) but has been relatively rare. Our results highlight the need to revise the taxonomy of Cyzicidae and Leptestheriidae and provide evidence that the global spinicaudatan diversity may be underestimated due to the presence of numerous cryptic species. We establish Eocyzicidae fam. nov. to accommodate the genus Eocyzicus. Consequently, Cyzicidae comprises only two genera-Cyzicus and Ozestheria. Ozestheria occurs also in Africa and Asia and Ozestheria pilosa new comb. is assigned to this genus.

The large branchiopod crustacean fauna (fairy shrimp, tadpole shrimp and clam shrimp) of the Neotropical Bioregion are incompletely known, with scattered records for many taxa, and many new taxa discovered and described regularly. As an aid to furthering our knowledge of the group in this region, we present an assortment of notes and records on various Neotropical taxa. We present our information in the form of a checklist, listing all reported species, with a review of their known distribution, with 56 new distributional records for 29 taxa. We also include a revised description of Spiralifrons mira based on new material from Brazil, and provide important comments on the Leptestheriidae, reducing Strakrabiidae, Straskrabia, and Brtekia to synonymy. The information presented here will assist in additional studies, surveys, and conservation, as well as help develop a biogeographical understanding of this vast region. Thus, we have compiled these records so that it will be available to other researchers. Future survey efforts will undoubtedly reveal additional records and taxa. Fil: Rogers, D. Christopher. University of Kansas; Estados Unidos Fil: Severo Neto, Francisco. Universidade Federal do Mato Grosso do Sul; Brasil Fil: Volcan, Matheus Vieira. Instituto Pró-Pampa. Laboratorio de Ictiología; Brasil Fil: De los Ríos, Patricio. Universidad Católica de Temuco; Chile Fil: Epele, Luis Beltran. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Centro de Investigación Esquel de Montaña y Estepa Patagóica. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ciencias Naturales - Sede Esquel. Centro de Investigación Esquel de Montaña y Estepa Patagónica; Argentina Fil: Ferreira, Aloisio. MUNDI. Biología Integrada Ltda; Brasil Fil: Rabet, Nicolas. Sorbonne University; Francia. Université Pierre et Marie Curie; Francia. Universite de Caen Basse Normandie; Francia. Muséum National d'Histoire Naturelle; Francia. Centre National de la Recherche Scientifique; Francia

A new species of smooth clam shrimp (Branchiopoda: Laevicaudata) from Mongolia and China is described here based on both morphological and genetic differences. The new species, Lynceus grossipedia n. sp., has unique features, including asymmetrically modified male thoracopods (left side thoracopods III-VI), male claspers “movable finger” (=endopod) with delicate setation, and broad, bicarinate male and female rostrum. Lynceus grossipedia n. sp. is compared with the genera Paralimnetis Gurney, 1931 and Lynceiopsis Daday, 1912 and a recently described Lynceus Müller, 1776 from China, also showing modified male thoracopods. Lynceus mandsuricus Daday, 1927 is declared nomen inquirendum. DNA barcoding has not previously been applied on smooth clam shrimp taxonomy, so we generated new cytochrome c oxidase (COX1) data for 10 Lynceus species in order to explore its usefulness for Laevicaudata. Previous Laevicaudata sequences in GenBank were scarce (~50) and biased, with 62% (n=31) being assigned to a single taxon (i.e., Lynceus macleayanus) and 28% (n=14) not assigned to species. Based on the addition of new barcoding data and the comparison with GenBank data for other clam shrimps, we conclude that distance thresholds between species (=barcoding gap) are similar for all three suborders (Spinicaudata, Cyclestherida, and Laevicaudata)., The study is part of ZS’s PhD studies financed by the Faculty of Science, University of Copenhagen as well as SS’s PhD studies financed by Applied Taxonomic Research Center of Khon Kaen University, Southeast Asia Biodiversity Research Institute, the Chinese Academy of Sciences (Y4ZK111B01), and the National Natural Science Foundation of China (31702011).

Non-marine Cretaceous red beds are widely distributed in south-east China. Clam shrimps are one of the most useful fossil groups for biostratigraphic correlation of these strata. The fossil clam shrimp genus Linhaiella Chen and Shen, 1982 was originally described from a sequence of the Upper Cretaceous red beds, which belongs to the Fangyan Formation in the Xianju Basin of Zhejiang Province, south-east China. Morphological study of Linhaiella from Zhejiang under an SEM has revealed new taxonomic features not previously recognized: (1) growth bands near umbo ornamented by slender radial lirae that are relatively widely spaced with intercalated fine reticulations; (2) growth bands in the middle to ventral parts of the carapace ornamented with no reticulation, but a row of pits along the lower margin of each growth band.

We present records of 3 clam shrimp species from New York: 2 spinicaudatan species— Eulimnadia agassizii (Agassiz Clam Shrimp; the first record for the state) and Cyzicus sp. (the second record of the genus from the state)—and Lynceus brachyurus (Laevicaudata; Holarctic Clam Shrimp; first reported from New York in 1883, is herein documented from the Hudson Valley). Some of the temporary waters that these species inhabit are protected by wetland regulations, but rain-puddle habitat on or along unimproved roads has no such protection.

A Purbeck clam shrimp (Subclass Phyllopoda, Order Diplostraca) fauna is described based on a new collection, containing Liograpta subquadrata (Sowerby in Fitton, 1836) and Carapacestheria? lulworthensis sp. nov. from the Freshwater Beds, and an unidentified taxon from the Caps and Dirt Beds of the Purbeck Limestone Formation (Tithonian–Valanginian) of southwest England (UK). The scanning electron micrographs clearly show that Liograpta has puncta on growth bands near the umbo; puncta also occur between the radial lirae on the middle and ventral parts of the carapace. This newly identified type of carapace ornamentation does not occur in previously described Liograpta species from localities outside the UK, which should be moved out of Liograpta (Novozhilov, 1954). The Middle Jurassic Wolfestheria patagoniensis (Tasch in Tasch and Volkheimer, 1970) from Argentina has typical puncta and radial lirae ornamentation, and it should be assigned to Liograpta.

Early Cretaceous clam shrimp specimens of Yanjiestheria were first discovered in the Lishugou Formation at Wudaohezi in northwestern Huanren Manchu Autonomous County of eastern Liaoning in 1930, which played an important role for understanding of the terrestrial palaeoenvironment in East Asia. In 2019, a new geological investigation has reported the first discovery of the clam shrimp Eosestheria (a common component of the Jehol Biota) from the Lishugou Formation at Xiaowenzhigou in northwestern Huanren in 2019. A detailed taxonomic study of these newly collected clam shrimp specimens revealed that their growth bands are ornamented with very fine reticulation (mesh diameter about 20–30 μm) in the dorsal and antero-ventral parts of the carapace. Densely spaced radial lirae are also observed in the ventral and postero-ventral parts of the carapace (about 40–50 lirae within a width of 1 mm). Through comparison with the type specimen from Wudaohezi, northwestern Huanren, the newly collected clam shrimp specimens are not an eosestheriid, but are conspecific with Yanjiestheria huanjenensis (Novozhilov, 1954).