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Notostracan branchiopods reported from the Lower Triassic Voltzia Sandstone Lagerstätte in northeastern France have previously been assigned to Triops cancriformis, making this species the longest persisting animal in earth history. Careful restudy of the splendidly preserved material indicates that the species can be well characterized but represents a notostracan genus and species that cannot be assigned to the Triopsidae. This undermines the concept of its being a 'living fossil'. The name Apudites antiquus, under which the first known specimens were described, is available and appropriate for the species. Some of the specimens of Apudites antiquus offer morphological details of a quality that ranks them among the best‐preserved fossil non‐marine arthropods. The Voltzia Sandstone specimens previously assigned to the extant species T. cancriformis include two additional, peculiar diplostracan branchiopods, Olesenocaris galli gen. et sp. nov. and Grauvogelocaris alsatica gen. et sp. nov., both with unique morphological features that characterize them as representatives of as yet unknown families. [ABSTRACT FROM AUTHOR]

Three collections of clam shrimp from the Lower Devonian (upper lower Emsian) Klerf Formation of Willwerath and Waxweiler in the western Eifel Mountains are herein studied. Four discernible morphotypes are present in the Willwerath assemblage. These morphotypes correspond to the previously described species from this locality: Pseudestheria diensti (Gross), Pseudestheria subcircularis Raymond, and Palaeolimnadiopsis? eifelensis Raymond. The fourth morphotype also closely corresponds to Pseudestheria diensti, but is slightly different in outline. Asmussia willweratica (Novozhilov) is an objective synonym of Pseudestheria subcircularis. In the Willwerath clam shrimp sample, it is difficult to disentangle taphonomic/preservational versus ontogenetic/sexual variation. If taphonomic/preservational causes could be confirmed, all the Willwerath specimens may represent just one taxon and Pseudestheria subcircularis and Palaeolimnadiopsis? eifelensis would be potential subjective synonyms of Pseudestheria diensti. However, we refrain from a formal taxonomic act, which requires a larger number of specimens to be analysed. In addition, we investigated two samples from Waxweiler, which originate from distinct centimetre-thick layers and therefore represent associations. One of these associations comprises two discernible clam shrimp morphotypes. Because of limited preservation of morphological characters, one is here left in open nomenclature as Spinicaudata incertae sedis, whereas the other is recognised as a new species of the family Palaeolimnadiopseidae, Palaeolimnadiopsis frankeorum sp. nov. The second association from Waxweiler comprises at least four, possibly six different clam shrimp taxa. In addition to Pseudestheria diensti, Palaeolimnadiopsis sp., and poorly preserved Asmussia- and Ulugkemia-like specimens, two taxa can be described as new, namely the vertexiid Cornia wasvilrensis sp. nov. and the leaiine Eicheleaia wenndorfi gen. nov. et sp. nov. Altogether, the Klerf Formation at Waxweiler yields a total of at least five (possibly eight) clam shrimp taxa. The palaeoenvironment of these early clam shrimp from the Klerf Formation is interpreted as a non-marine, relatively proximal deltaic setting with no or very minor marine influence, such as a deltaic freshwater pond or lake. The comparatively high diversity of these lower Devonian clam shrimp suggests a considerably earlier origin and cryptic evolution of the group. [ABSTRACT FROM AUTHOR]

Only a small proportion of the world's crustacean taxa is adapted to limno-terrestrial microhabitats that are disconnected from conventional surface waterbodies. In rare occasions, water films on terrestrial tropical and subtropical vegetation may also harbour specialised cladocerans. Bryospilus Frey, 1980 (Chydoridae) is the only genus within the class Branchiopoda that is specialised to living almost exclusively in water-saturated terrestrial moss patches, leaf litter, and phytotelms. The remarkable waterflea lineage, which has a suite of highly unusual characters within the family, has been found in terrestrial habitats in rainforests of West Africa, South and Central America, and New Zealand. We discovered a new moss-inhabiting chydorid from western India, Bryospilus (Indobryospilus) bharaticus n. sp. , the first representative of the genus from the Oriental Region. Its morphology and behaviour are highly unusual for a species of Bryospilus. In comparison to its congeners, the new species can swim and it has significantly less oligomerisation, with three terminal setae on the antennal endopod instead of two and seven exopod setae on the third limb instead of six, among other features. We define a new subgenus Indobryospilus nov. and we amend the genus Bryospilus. The new species is a living evolutionary connection, characterised by a phenotype which provides us with new clues about evolutionary transitions in the only terrestrial branchiopod genus. Our results are informative beyond Cladocera, as the morphology of this species provides insights about the evolution and parallelisms of aquatic crustaceans that have specialised in limno-terrestrial habitats. We revisit the morphology of the genus, the disjunct biogeographical pattern with a potential ancient signature, and discuss the functional adaptations of these cladocerans to life on land, as well as convergences with subterranean lineages. A new key to the world species of Bryospilus species is included. [ABSTRACT FROM AUTHOR]

The taxonomy of the notostracan Lepidurus Leach, 1819 is complicated by a large number of synonymised species and extensive intraspecific variability in many relevant characters. We demonstrate, based on an integrative taxonomic approach, that the Ukrainian populations of Lepidurus are not conspecific with any currently accepted Lepidurus species and assign them to the previously synonymised species Lepidurus middendorffii comp. nov. (Braem, 1893). This species exemplarily highlights the problems in the taxonomy of Lepidurus. The species was originally described as Apus extensus var. middendorffii (Braem, 1893), but L. extensus is a junior synonym of Lepidurus lubbocki (Brauer, 1873), which is currently treated as a subspecies of Lepidurus apus (Linnaeus, 1758). Our molecular genetic analyses based on mitochondrial COI, 12S, 16S, and nuclear 28S, which included published data, suggest the presence of further, possibly cryptic species that await formal recognition and stress the importance for a more extensive revision of Lepidurus. The original type specimens of L. middendorffii , previously stored at the Museum of Natural History (Wrocław University, Wrocław, Poland), are lost and a neotype is designated. Lepidurus middendorffii is characterised by the dorsal organ position between the ocular tubercle margins, the sharp carapace sulcus spines, the long supra-anal plate with many median spines, a telson length to carapace length ratio 0.18–0.35, and differs by > 9% uncorrected COI p -distances from all other Lepidurus species. [ABSTRACT FROM AUTHOR]

The current systematics of the large branchiopod crustaceans are reviewed in relation to other crustacean groups and from class to genus level. Calmanostraca and Diplostraca are raised to superorder, and †Kazacharthra and Notostraca are both treated as orders. Problems and needs regarding the systematics of large branchiopods are presented and discussed, with suggestions for moving forward, stressing the need for modern methods and defensible taxonomic definitions. Subdividing taxonomic categories may or may not be warranted, but should never be based on only one gene, or on limited taxon sampling. Furthermore, splitting species out as new genera, when the original genus is poorly defined can only lead to future problems. [ABSTRACT FROM AUTHOR]

In high-altitude (4500 m) freshwater lakes, Daphnia is the apex species and the dominant zooplankton. It frequently dwells in the same lake as the Gammarid. Branchiopoda, a class of Arthropoda, Crustacea, is a relatively primitive group in the subphylum Crustacea, which originated in the Cambrian period of the Paleozoic. The complete mitogenome sequence of Daphnia sp. (Branchiopoda: Cladocera) was sequenced and annotated in this study and deposited in GenBank. The sequence structure of this species was studied by comparing the original sequences with BLAST. In addition, we have also researched the mechanisms of their mitochondrial gene rearrangement by establishing a model. We have used the Bayesian inference [BI] and maximum likelihood [ML] methods to proceed with phylogenetic analysis inference, which generates identical phylogenetic topology that reveals the phylogenetic state of Daphnia. The complete mitogenome of Daphnia sp. shows that it was 15,254 bp in length and included two control regions (CRs) and 37 genes (13 protein-coding genes, 22 tRNAs and two ribosomal RNAs [16S and 12S]). In addition to tRNA-Ser (GCT), other tRNAs have a typical cloverleaf secondary structure. Meanwhile, the mitogenome of Daphnia sp. was clearly rearranged when compared to the mitogenome of typical Daphnia. In a word, we report a newly sequenced mitogenome of Daphnia sp. with a unique rearrangement phenomenon. These results will be helpful for further phylogenetic research and provide a foundation for future studies on the characteristics of the mitochondrial gene arrangement process in Daphnia. [ABSTRACT FROM AUTHOR]

The Cerrado is home of the headwaters of some important Brazilian basins. Such biome has a high diversity of animal and plant species with a high degree of endemism. This premise is well documented for microcrustaceans of the Superorder Cladocera, although many areas still need sampling. In this context, the objective of the present investigation was to evaluate the geographic distribution and richness of Cladocera in the Cerrado biome. The analyzed data were obtained from the authors database on Brazilian Cladocera and distributed according to the hydrographic regions comprised in the biome. Species distribution models were used to determine the areas with the highest probability of occurrence of Cladocera. We analyzed 125 publications, resulting in 2829 records. In total, we obtained 161 taxa, belonging to 48 genera and seven families. Regarding the Hydrographic Regions, Paraná presented the highest richness, followed by TocantinsAraguaia and São Francisco. Our result indicates that most studies are concentrated in certain areas. Furthermore, the species distribution models indicated that transition areas between biomes have the highest probability of occurrence of genera and families. Our results indicate significant gaps in the knowledge, making it necessary to expand inventories and ecological studies in areas still unsampled. [ABSTRACT FROM AUTHOR]

ABSTRACT The genus Kurzia, initially described in 1894 by Dybowski and Grochowski, has a worldwide distribution and includes eight species. In Brazil, Kurzia polyspina is so far the only species considered valid. Here we report the first record of Kurzia media in Brazil, and the second record in South America. The material was collected in a lake in the Amazonian region of the Brazilian state of Maranhão. In addition, we provide some considerations about the taxonomic history of the species and discuss the need for a redescription and the designation of a neotype for K. media. With our record, K. media now has two known occurrence localities in northern North America and two in tropical South America, with a widely disjunct distribution that needs further elucidation.

The present study describes two occurrences of clam shrimps (“Conchostraca”). Following a form-based classification of Schneider et al. (2005, 2022) and Schneider & Scholze (2018), the conchostracans have been classified as Pseudestheria form Oberbozen and Pseudestheria form Le Fraine. They come from the Guncina and Tregiovo formations, repectivey. These units are part of the northern Athesian Volcanic Group, North Italy. All of this material were obtained from grey coloured, fine-grained siliciclastic, lacustrine deposits of Kungurian (late Cisuralian, late Early Permian) age. Their carapace valves in lateral view are marked by concentric ribs. Often, growth lines can be observed to decrease in their preservation towards the umbonal area of the valve. An open nomenclature is applied to the taxonomy at the species level herein, because of either limited number of individuals or a plastic deformation due to tectonics. So far, the records reported herein are restricted geographically and stratigraphically to respective single occurrences. Further studies are recommended to establish their full biostratigraphic ranges.

The loss of freshwater wetlands worldwide has underscored the importance of restoration to enhance biodiversity and functional objectives. While aquatic invertebrate communities within restored perennial freshwaters are well studied, few studies have occurred in the greatly reduced habitat of seasonal wetlands, such as vernal pools. California vernal pools have experienced high habitat loss and support many threatened or endangered invertebrate species. We compared 90 natural and 90 restored vernal pools of different ages across 10 sites throughout California and Southern Oregon using the Sars' method. Large branchiopod abundance, total invertebrate abundance, class richness, and community composition were assessed between pool types (natural vs. restored) and along environmental gradients (e.g. site, pool depth, surface area, age since restoration). Large branchiopod and total invertebrate abundance were 215 and 274% higher in natural pools than restored pools, but class richness was not different. Community composition was significantly different and driven by greater abundances of vernal pool fairy shrimp, San Diego fairy shrimp, Ostracoda, Cladocera, and Copepoda in natural pools. Few environmental or habitat variables explained patterns in richness or abundance. Our work demonstrates that restored pools, even those decades old, are different than natural pools. Future mitigation and monitoring guidelines for restored vernal pools should include quantitative evaluations for aquatic invertebrates. Restored pools are not adequate compensation for lost natural pools because they do not have the same ecological functions and values. [ABSTRACT FROM AUTHOR]

Introduction: The phylogenetic relationships within Pancrustacea (including Crustacea and Hexapoda) remain elusive despite analyses using various molecular data sets and analytical approaches over the past decade. The relationship between the major lineages of Allotriocarida, which includes Hexapoda, the most species-rich animal taxon, is particularly recalcitrant. Methods: To investigate and resolve the root of phylogenetic ambiguity in Pancrustacea, we re-evaluated the evolutionary relationships of major pancrustacean clades using a phylogenetically informed orthology approach and assessed the effect of systematic errors, with a major focus on long branch attraction (LBA) and incomplete lineage sorting (ILS). A data set comprising 1086 orthologs from 106 species representing all major extant classes of pancrustaceans was assembled and used in gene tree and species tree construction after various filtering processes. Results and discussion: Regardless of the filtering criteria and phylogenetic analyses, the resulting trees consistently supported (1) a sister relationship of Remipedia and Hexapoda (hence rejecting the monophyly of Xenocarida, i.e. Remipedia + Cephalocarida), and (2) refuted the monophyly of Multicrustacea, as Copepoda is either sister to or nested within Allotriocarida. Examination of gene trees reveals that the grouping of Multicrustacea and Xenocarida in previous phylogenetic studies may represent LBA artefacts. Phylogenetic signal analyses suggest a low resolution and an incidence of strong conflicting signals at the deep splits. Further analyses indicate a partial contribution of incomplete lineage sorting (ILS) to the contradictory signal in the allotriocaridan phylogeny, leading to limited support for any potential relationships between Branchiopoda, Cephalocarida and Copepoda. This study suggests the need for further examination of other potential sources of signal discordance, such as introgression and gene tree estimation error to fully understand the evolutionary history of Pancrustacea. [ABSTRACT FROM AUTHOR]

Molecular analyses based on the comparison of Chirocephalus species mtDNA cytochrome oxidase I (COI) sequences obtained from Algeria, Morocco and France with other available sequences were performed. The analysis clarified the status of the genus Chirocephalus Prévost, 1803 in Algeria and its phylogenetic links with other populations. Three lineages occur in Algeria representing three different species: Chirocephalus salinus Daday, 1910, C. sanhadjaensis Boumendjel, Rabet and Amarouayache, 2018 and a new species sampled in Reghaïa (Alger, Algeria) near Algiers. All these species, belonging to the "diaphanus" group, seem to be endemic to Algeria except C. salinus also present in France (Corsica). The new species C. algeriensis sp. n. is described and its affinities with other species of the genus are presented. This species is until now restricted to Algiers region and shares several characters with C. diaphanus Prévost, 1803. It is separated from all other species by the shape and size of the second antennal appendages of the male and the female. The resting eggs of C. algeriensis sp. n. are morphologically similar to those of many Chirocephalus but a variation of size of eggs can be used at a specific level. [ABSTRACT FROM AUTHOR]

New finds of fossil assemblages of brachiopods, mollusks, crinoids, arthropods and fishes, as well as terrestrial plants from a part of the Dyakove Group, which corresponds to the coal-bearing Mandrykyne Formation and the lower part of the Mospyne Formation and is exposed in the southern part of the Luhansk Region, were studied. For the first time, a brachiopod assemblage consisting of species of the genera Crurithyris, Tiramnia, Alphachoristites, Lissochonetes were identified in these rocks. In addition, phyllocarids and impressions of terrestrial plants of the genera Halonia, Calamites, Pinnularia, Paripteris, Eusphenopteris, Artisia and Cordaites were found in the Dyakove Group for the first time. Bivalves and gastropods in the studied collection are represented by the genera Phestia, Palaeoneilo, Nuculavus, Solenomorpha, Sanguinolites, Posidoniella, ?Euchondria, ?Nodospira, Euphemites, Retispira, Glabrocingulum, Rhineoderma, Angyomphalus, and Naticopsis. Cephalopods are represented by the species of the genera Gzheloceras, ?Pseudogzheloceras, Melvilloceras, Retites, Gastrioceras and ?Owenoceras. In addition to the above groups, the rocks also contain the crinoids Platyplateium, Platycrinites, ?Unilineatocrinus and Bicostulatocrinus as well as fragments of fin spines of acanthodians Gyracanthidae indet. and isolated unidentified fish scales. [ABSTRACT FROM AUTHOR]

The fairy shrimp Branchinectella media, because of its passive dispersal capacity and scarce and irregularly distributed habitats (temporary saline aquatic systems), is an intriguing organism from a population genomics and conservation perspective. Stochasticity of dispersal events and the irregular distribution of its habitat might lead to low levels of population connectivity and genetic diversity, and consequently, populations with limited persistence through time. Indeed, by using genomic data (SNPs), we found a strong genetic structure among some of the geographically isolated Iberian populations of B. media. Interestingly, we also obtained high estimates of effective population sizes. Lack of suitable habitat between populations (absence of a "stepping stone" network) and strong genetic differentiation suggest limited dispersal success in B. media. However, the high effective population sizes observed ensure persistence of B. media populations against genetic stochasticity (genetic drift). These results indicate that rescue-effect might not be essential for population persistence if they maintain high effective population sizes able to hold adequate levels of genetic diversity. Should high population sizes be reported in other low dispersing Anostraca, one might be optimistic with regard to their conservation status and fate, provided that their natural habitats remain undisturbed. [ABSTRACT FROM AUTHOR]

Thirty-five cladocerans species are recorded from La Española lagoon in the Orinoquia region of Colombia; all are new records for Meta Department and 10 for Colombia. With the addition of these new reports, the total number of cladocerans for Colombia and the Meta department is increased by 124 and 38 species, respectively. The cladoceran fauna from the surveyed area is represented mainly by widespread species, commonly found in the Neotropical regions, but local morphological data are scarce in the regional literature. Brief diagnostic description of 18 species of cladoceran fauna recorded of the Meta department-Colombia are provided together with illustrations of taxonomically significant appendages, morphological remarks, notes on the variability of some species, and their distribution. [ABSTRACT FROM AUTHOR]

Lepidurus couesii is a large freshwater branchiopod that is distributed broadly around the world. In this study, we used molecular and morphological methods to identify and record Lepidurus cf. couesii for the first time in Iran. The Almalou Gul specimens presented the characteristic number of rings, mediodorsal spines on the supra-anal plate, and the sulcus spines of the species L. couesii. A complete morphological characterization of the species and a comparison with previous records of Lepidurus apus in Iran is included in this work. Phylogenetic analysis based on the COI gene recovered the Iranian specimens as an independent lineage within the L. couesii species complex. The GMYC and the ASAP species delimitation models calculated at least four independent lineages within the L. couesii species-complex, some of them with probably restricted distributions. This study stresses –once again– the presence of several species-complexes within this group of crustaceans and the necessity to include molecular phylogenetic research to recognize the specific occurrence of different lineages within the genus Lepidurus. [ABSTRACT FROM AUTHOR]

Terrestrial crustaceans are represented by approximately 4,900 species from six main lineages. The diversity of terrestrial taxa ranges from a few genera in Cladocera and Ostracoda to about a third of the known species in Isopoda. Crustaceans are among the smallest as well as the largest terrestrial arthropods. Tiny microcrustaceans (Branchiopoda, Ostracoda, Copepoda) are always associated with water films, while adult stages of macrocrustaceans (Isopoda, Amphipoda, Decapoda) spend most of their lives in terrestrial habitats, being independent of liquid water. Various adaptations in morphology, physiology, reproduction, and behavior allow them to thrive in virtually all geographic areas, including extremely arid habitats. The most derived terrestrial crustaceans have acquired highly developed visual and olfactory systems. The density of soil copepods is sometimes comparable to that of mites and springtails, while the total biomass of decapods on tropical islands can exceed that of mammals in tropical rainforests. During migrations, land crabs create record-breaking aggregations and biomass flows for terrestrial invertebrates. The ecological role of terrestrial microcrustaceans remains poorly studied, while omnivorous macrocrustaceans are important litter transformers and soil bioturbators, occasionally occupying the position of the top predators. Notably, crustaceans are the only group among terrestrial saprotrophic animals widely used by humans as food. Despite the great diversity and ecological impact, terrestrial crustaceans, except for woodlice, are often neglected by terrestrial ecologists. This review aims to narrow this gap discussing the diversity, abundance, adaptations to terrestrial lifestyle, trophic relationships and ecological functions, as well as the main methods used for sampling terrestrial crustaceans. [ABSTRACT FROM AUTHOR]

The fairy shrimp genus Parartemiopsis Rogers, 2005 currently contains a single species reported from Russia and Mongolia. In 2013, an unidentified Parartemiopsis population was reported from the eastern margin of the Tibetan Plateau in China's Yunnan Province, from Patatson National Park in Shangri-La County. Here, we describe the Chinese populations as a new species, Parartemiopsis shangrilaensis sp. nov. This new species is distinguished from its congener, P. longicornis (Smirnov, 1930), by the form of the male second antennae and the gonopod. The discovery of P. shangrilaensis sp. nov. extends the known distribution of the genus, and more Parartemiopsis species may be found in the future. We present a key to the genera and species of Chirocephalidae in China as an aid to future research. [ABSTRACT FROM AUTHOR]

The enigmatic acid-resistant mesofossil genus Kuqaia is emended, a new species (Kuqaia scanicus) is instituted, and three established species are described from the Lower Jurassic (lower Pliensbachian) of the Kävlinge BH-928 core, in southern Sweden. Kuqaia has a distribution across the middle northern latitudes of Pangaea and is restricted to Lower to lower Middle Jurassic strata. Morphological characters support Kuqaia being the ephippia (resting egg/embryo cases) of Cladocera (Crustacea: Branchiopoda), and a probable early stem-group taxon of the Daphnia lineage. The paleoecology of the small planktonic crustaceans indicate purely fresh-water environments, such as lakes or ponds, all occurrences being in continental deposits, and the Kuqaia specimens possibly represent dry-season resting eggs. Chemical analyses of these and similar fossils, and of extant invertebrate eggs and egg cases are recommended to improve resolution of the biological affiliations of such mesofossil groups. [ABSTRACT FROM AUTHOR]

Branchinecta serrata Rogers, 2006 was originally thought to be limited to four localities in the central USA. We present new records of this species in prairie pools in central Canada, greatly extending its known distribution. Previous records from Canada were misidentified as the common and widespread B. paludosa (Müller, 1788). We present images emphasizing the differences between the two species, updated geochemical tolerance data, and revise the conservation status of B. serrata. Finally, we present an identification key to the Branchinecta paludosa species group. [ABSTRACT FROM AUTHOR]

Trehalose is important in activity, development, and environmental-stress response, especially in invertebrates. It is mainly synthesized by trehalose-6-phosphate synthase (TPS) and trehalose-6-phosphate phosphatase (TPP), and degraded by trehalase (TRE). In the present study, the tps , tpp , and tre were identified from various crustacean species and their phylogeny, structure, network, and transcriptome were analyzed. The tps and tpp are fused in crustaceans, accompanied with multi-copies of genes to improve the synthesis capacity of trehalose, and they may be formed by whole-genome duplication (WGD) and/or segmental duplications. Phylogenetic subgroups of enzymes in the same species may be due to the different lengths and distribution positions of domains. The protein with single TPP domain in the salmon louse, the copepod Lepeophtheirus salmonis (Krøyer, 1837), probably has a depoisoning effect. Structure analyses and location predictions showed that crustacean TRE possess an α-helix-rich structure with barrel core, and are membrane-bound, cytoplasmic, and secreted. Additionally, the non-acid TRE might not be adjusted by Ca2+ because there is no binding domain in crustaceans. Expression profiles of different tissues, developmental periods, and environmental-challenge responses, as well as genes of co-expression networks suggested that TPS (including TPP) and TRE might play important roles in physiological activities including development and environmental adaptation in crustaceans. Multi-copies of tre may enhance survival ability of copepods in diverse and sometimes harsh environments. Branchiopods, copepods, and the marine shrimp Penaeus vannamei Boone, 1931 are suspected to adopt possible acid TRE as a supplementary strategy in response to stress. [ABSTRACT FROM AUTHOR]

An updated checklist of the cladoceran fauna from inland aquatic habitats in Thailand (a high-diversity hotspot in Southeast Asia), based on published cladoceran records found in literature is presented. The checklist updates nomenclature and species distributions, especially habitat preferences. A total of 138 valid recorded species is relatively high. However, the estimators indicate that more species are expected to be found with more research. The north-eastern and southern regions of Thailand are well-studied regions of high species richness with 100 and 96 cladoceran species, respectively, whereas the northern and eastern regions have large research gaps that should be studied further. Moreover, each habitat type seems to have a unique cladoceran community as the similarity values amongst them are mostly low (Sorensen similarity index < 0.50). Therefore, it is suggested that habitats with unique characteristics, such as peat swamps, stream and cave pools, are worthy of further exploration. If the current records of cladoceran diversity in Thailand confirms a high diversity of this animal in the tropical region, then the geographical distribution of each species can be properly explained. [ABSTRACT FROM AUTHOR]

Abstract Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host–parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role.

Daphnia pulex is a natural food widely used in aquaculture, and S6K plays an important role in protein translation and ageing. To explore the function of S6K in the ageing process of D. pulex , we cloned and analysed the full-length cDNA of S6K. With the growth of D. pulex , the expression of S6K mRNA first increased, then peaked at 10 days, and then decreased. Western blot analysis showed that the S6K protein expression increased from 1 to 5 days of age, but did not change significantly from 5 to 25 days of age. RNAi knockdown of S6K, reduced the expression of S6K mRNA and S6K protein, and it causes changes in other genes associated with ageing in both sexes. S6K may be involved in reproductive transformation, affecting reproductive capacity, thus significantly affecting the ageing of D. pulex. miRNA with potential regulation of the S6K gene were screened by the bioinformatics method and validated using a dual luciferase reporter gene system. This study deepens our understanding of the mechanisms of ageing in D. pulex and expands our understanding of the role of S6K in the ageing process. [ABSTRACT FROM AUTHOR]

Mediterranean wetlands are suitable ecosystems for studying metacommunity theory, since they are isolated ecosystems within a land matrix with well-established limits, often with watersheds destined for agricultural uses. The zooplankton community of wetlands in agricultural landscapes is the result of processes that operate in a different multiscale context. We selected 24 ponds in Alto Guadalquivir region (SE Spain) with different local environmental variables (biological, limnological and land uses). The zooplankton community of the wetlands under study consists of a total of 60 species: 38 branchiopods and 22 copepods. This community (total, branchiopods and copepods) was analysed through two different and complementary metacommunity approaches. The pattern approach determines the species distribution along environmental gradients, and the mechanistic approach considers the involved processes, such as environmental control and dispersal limitation. The results indicated a nested metacommunity, in which five limnological variables, three land uses and six spatial variables are the main drivers that explain zooplankton distribution in these wetlands. In conclusion, species sorting and dispersal processes play a role in the structuring of the zooplankton metacommunity. This conclusion has implications for the development of adequate management policies on Mediterranean wetland protection and diversity conservation in agricultural contexts. [ABSTRACT FROM AUTHOR]

Very little is known about the feeding of naupliar and juvenile life stages of omnivorous fairy shrimps (Crustacea: Anostraca). Here, we aim to reveal whether the fairy shrimp Branchinecta orientalis is an ontogenetic omnivore and at which age and ontogenetic stage they gain the ability to feed on zooplankton. We assess how food uptake rates change with age until reaching maturity by providing algae (pico- and nanoplanktonic unicellular algae) and zooplankton (rotifers and copepod nauplii) as food in individual experiments. We found that the fairy shrimp B. orientalis started to feed on both types of algal prey immediately after hatching. Nanoplanktonic algae likely represented the most important food source until reaching maturity. Moreover, fairy shrimps started to feed on zooplankton already when they were 7 days old. Slow-moving rotifers gradually gained importance in the fairy shrimp diet with time. Our results reveal an ontogenetic change in the prey spectrum of fairy shrimp. The systematic shift towards omnivory likely affects both phyto- and zooplankton community composition, possibly contributing to temporal changes in food web dynamics in fairy shrimp habitats, and temporary ponds, which may warrant more detailed investigations in future studies. [ABSTRACT FROM AUTHOR]

The phylogenetic studies of clam shrimps (Branchiopoda, Crustacea) demonstrated that the significance of several morphological characters for classification of branchiopod shells should be critically re-evaluated. Such a venture is particularly important for integrating the taxonomy of fossil and extant branchiopods. One of the shell characters widely used in the branchiopod classification is the carapace ornamentation pattern. This character might, however, be significantly influenced by intraspecific variability and in particular the sexual dimorphism. In this study we investigate the pattern of ornamentation in extant branchiopods—including differences resulting from sexual dimorphism—in order to assess its value for branchiopod taxonomy. We examined 184 individuals representing 10 living species belonging to 7 genera, 5 families, and 2 suborders from China, and compared with the results of previous studies. Although some differences in ornamentation were related to reproductive modes, the basic ornamentation patterns or combinations were stable within each extant species. We found out that some taxa indeed display sexually dimorphic ornamentations, but their basic ornamentation patterns or combinations are stable within each species so they do not significantly influence the taxonomic identification. Integration of data on fossil and extant taxa indicates that similar ornamentation patterns can be observed on familial level of fossil spinicaudatan branchiopods and indicates therefore that characteristic ornamentation patterns can help to identify these taxa in the fossil record. In light of the new molecular phylogeny, we re-evaluated the phylogenetic relationship between fossil and extant spinicaudatan taxa. The resulting tree suggests: (i) paraphyly of the traditional Eosestherioidea, (ii) an affinity between Ozestheria and Triglypta, and (iii) an affinity between Cyzicus and Diestheria or Aquilonoglypta.

Numerous arthropods (e.g. branchiopods, insects) collected during the first half of the 20th century by F.-F. Mathieu within the Pennsylvanian-Cisuralian (Moscovian-Asselian) succession of the Zhaogezhuang colliery (Hebei Province, China), romanised notably as Chao Ko Chwang, or Chaokochuang, in the literature, have been recently located in the palaeontological collections of the Royal Belgian Institute of Natural Sciences (Brussels). This historical material from one of the classic localities of the Kaiping Coalfield includes a large number of wings of stem-Dictyoptera, mainly from the Tangshan Formation and to a lesser extent from the Kaiping and Zhaogezhuang formations. The exceptional richness in insects of a particular horizon developed within the Moscovian part of the Tangshan Formation was already pointed out at the end of the 1920s by the French palaeoentomologist P. Pruvost, who provided the first account on the arthropods of Mathieu's collection from the Kaiping Coalfield. This singular Dictyoptera material was later studied by D. Laurentiaux in his unpublished Ph.D. thesis. In order to promote the revision of Mathieu's collection by specialists, we provide here a detailed scientific background and re-illustrate the arachnids (and formerly alleged ones: (Poliochera vel Curculioides) [sic] pustulatus Laurentiaux-Vieira & Laurentiaux), branchiopods (Lioestheria? mathieui (Pruvost)), and insects from the Zhaogezhuang colliery, notably using the Reflectance Transformation Imaging methodology. [ABSTRACT FROM AUTHOR]

We present the novel reference genome of the Versatile Fairy Shrimp, Branchinecta lindahli. The Versatile Fairy Shrimp is a freshwater anostracan crustacean found across the western United States from Iowa to Oregon and from Alberta to Baja California. It is an ephemeral pool specialist, living in prairie potholes, irrigation ditches, tire treads, vernal pools, and other temporary freshwater wetlands. Anostracan fairy shrimp are facing global declines with 3 species in California on the Endangered Species list. This species was included in the California Conservation Genomics Project to provide an easily accessible reference genome, and to provide whole-genome resources for a generalist species, which may lead to new insights into Anostracan resiliency in the face of climate change. The final gapped genome comprises 15 chromosome-length scaffolds covering 98.63% of the 384.8 Mb sequence length, and an additional 55 unscaffolded contigs. [ABSTRACT FROM AUTHOR]

The Taxonomic Catalog of the Brazilian Fauna (CTFB) is an initiative involving the effort of hundreds of researchers in several institutions, including international partners. Its main objective is to make public and give free access to a checklist of valid species occurring in Brazil. This catalog includes information on Cladocera, a group of microcrustaceans that occupy inland water and marine ecosystems. In this study, we evaluated the Cladocera part of the Brazilian Fauna Catalog. Among the taxa described or reported, we observed 155 valid species (37 endemic) and 61 genera (2 endemic) distributed in 11 families. European researchers represented 50% of all the authors involved in descriptions of species, and European collections keep most primary types, although many species have types that have been lost or not designed. Brazilian researchers were involved with a large number of descriptions, especially in the last 15 years. Our findings indicated that Cladocera taxa were observed in all hydrographic regions (Paraná with 119 species), biomes (Atlantic Forest with 126 species) and states, except state of Rondônia. The catalogue of Brazilian cladoceran fauna should be improved, as there are still large geographic ranges to be sampled in Brazil. [ABSTRACT FROM AUTHOR]

Fossil spinicaudatan taxonomy heavily relies on carapace features (size, shape, ornamentation) and palaeontologists have greatly refined methods to study and describe carapace variability. Whether carapace features alone are sufficient for distinguishing between species of a single genus has remained untested. In our study, we tested common palaeontological methods on 481 individuals of the extant Australian genus Ozestheria that have been previously assigned to ten species based on genetic analysis. All species are morphologically distinct based on geometric morphometrics (p ≤ 0.001), but they occupy overlapping regions in Ozestheria morphospace. Linear discriminant analysis of Fourier shape coefficients reaches a mean model performance of 93.8% correctly classified individuals over all possible 45 pairwise species comparisons. This can be further increased by combining the size and shape datasets. Nine of the ten examined species are clearly sexually dimorphic but male and female morphologie strongly overlap within species with little influence on model performance. Ornamentation is commonly species-diagnostic; seven ornamentation types are distinguished of which six are species-specific while one is shared by four species. A transformation of main ornamental features (e.g. from punctate to smooth) can occur among closely related species suggesting short evolutionary timescales. Our overall results support the taxonomic value of carapace features, which should also receive greater attention in the taxonomy of extant species. The extensive variation in carapace shape and ornamentation is noteworthy and several species would probably have been assigned to different genera or families if these had been fossils, bearing implications for the systematics of fossil Spinicaudata. [ABSTRACT FROM AUTHOR]

Daphniopsis tibetana is widely distributed in Xinjiang, Qinghai, Tibet of China, as well as in Russia and India, which is the dominant zooplankton in many high-altitude (4000 m) salt lakes. D. tibetana can adapt to saline waters, whereas the other species of the superorder Cladocera can only inhabit in freshwater. However, the phylogenetic status of D. tibetana in Branchiopoda remains unclear primarily because of limited mitogenome. In this study, complete mitochondrial genome sequences of D. tibetana were sequenced and annotated for the first time to obtain a comprehensive understanding of its phylogenetic status. The complete mitogenome of D. tibetana is 16196 bp in length. It contains 37 genes, including two ribosomal RNAs (12S and 16S rRNAs) genes, 22 transfer RNA (tRNA) genes, 13 protein-coding genes, and one non-coding region. The overall base composition is 29.6% A, 33.2% T, 19.0% G, and 18.2% C with a high AT bias (62.8%). Except for trnS1 (GCT), most tRNAs have a typical cloverleaf secondary structure. Phylogenetic analysis based on maximum likelihood and Bayesian inference generates identical phylogenetic topology and shows the phylogenetic status of D. tibetana, which reconfirm the distinction between the genera Daphniopsis and Daphnia. Meanwhile, the class Branchiopoda is clustered into three clades (Anostraca, Notostraca, and Diplostraca) with high support values. These results provide not only a comprehensive understanding of the characteristics of D. tibetana mitogenome and its phylogenetic position in Diplostraca, but also information for future research on the phylogeny of Branchiopoda. [ABSTRACT FROM AUTHOR]

Abstract Background Fairy shrimps belong to order Anostraca, class Branchiopoda, subphylum Crustacea, and phylum Arthropoda. Three fairy shrimp species (Eubranchipus uchidai, E. asanumai, and E. hatanakai) that inhabit snowmelt pools are currently known in Japan. Whole mitochondrial genomes are useful genetic information for conducting phylogenetic analyses. Mitochondrial genome sequences for Branchiopoda members are gradually being collated. Results Six whole mitochondrial genomes from the three Eubranchipus species are presented here. Eubranchipus species share the anostracan pattern of gene arrangement in their mitochondrial genomes. The mitochondrial genomes of the Eubranchipus species have a higher GC content than those of other anostracans. Accelerated substitution rates in the lineage of Eubranchipus species were observed. Conclusion This study is the first to obtain whole mitochondrial genomes for Far Eastern Eubranchipus species. We show that the nucleotide sequences of cytochrome oxidase subunit I and the 16S ribosomal RNA of E. asanumai presented in a previous study were nuclear mitochondrial DNA segments. Higher GC contents and accelerated substitution rates are specific characteristics of the mitochondrial genomes of Far Eastern Eubranchipus. The results will be useful for further investigations of the evolution of Anostraca as well as Branchiopoda.

Time-series are fundamental for enhancing our comprehension of plankton community dynamics and forecasting future changes that could significantly affect entire marine food chains and ecosystems. In this study, we investigated spatial and temporal variations in occurrence, abundance and body size of marine branchiopods in the Belgian Part of the North Sea (BPNS), using both traditional microscopy, as well as digital imaging (ZooSCAN). We studied the population dynamics of branchiopods collected between 2014 and 2021 in the BPNS and compared these results with a previously collected (2009–2010) dataset for the same area. The time series showed no significant changes in abundance (Podon spp., Evadne nordmanni) over the years, but we did observe a pronounced seasonal pattern, with both species completely absent in the winter months. Abundance and biomass were positively correlated with water temperature but negatively correlated with nutrient concentrations and turbidity. Additionally, Podon spp. abundance was negatively correlated with anthropogenic chemicals (i.e., polycyclic aromatic hydrocarbons). We employed generalized additive models to quantify the relative contribution of temperature, salinity, turbidity, chlorophyll a concentration and pollutant levels to the dynamics of the studied taxa. Turbidity and chlorophyll a concentrations were revealed to be the predictor with the highest importance in all models predicting the abundances/body size of the selected species. Anthropogenic chemicals were not informative in explaining branchiopod abundance or body size. The findings of this study establish a baseline for future studies, which is essential for our understanding of the zooplankton dynamics in the North Sea, particularly in the context of climate change and changing water quality. • We report an update of marine branchiopod dynamics in the southern North Sea. • We found seasonal differences in branchiopod abundance, but no clear spatial trends. • GAMs identified turbidity as a key predictor for species abundance and body size. • GAMs do not suggest an impact of persistent organic pollutants on abundance/body size. [ABSTRACT FROM AUTHOR]

Hox and ParaHox genes (HPHGs) are key developmental genes that pattern regional identity along the anterior–posterior body axis of most animals. Here, we identified HPHGs in tadpole shrimps (Pancrustacea, Branchiopoda, Notostraca), an iconic example of the so-called “living fossils” and performed a comparative genomics analysis of HPHGs and the Hox cluster among major branchiopod lineages. Notostraca possess the entire Hox complement, and the Hox cluster seems to be split into two different subclusters, although we were not able to support this finding with chromosome-level assemblies. However, the genomic structure of Hox genes in Notostraca appears more derived than that of Daphnia spp., which instead retains the plesiomorphic condition of a single compact cluster. Spinicaudata and Artemia franciscana show instead a Hox cluster subdivided across two or more genomic scaffolds with some orthologs either duplicated or missing. Yet, branchiopod HPHGs are similar among the various clades in terms of both intron length and number, as well as in their pattern of molecular evolution. Sequence substitution rates are in fact generally similar for most of the branchiopod Hox genes and the few differences we found cannot be traced back to natural selection, as they are not associated with any signals of diversifying selection or substantial switches in selective modes. Altogether, these findings do not support a significant stasis in the Notostraca Hox cluster and further confirm how morphological evolution is not tightly associated with genome dynamics.

The gene FoxO plays an important role in regulating individual growth and development, cell survival, and senescence, mainly through transcriptional regulation and the signal transduction pathway. In this study, the full-length cDNA sequence of the FoxO gene was cloned from Daphnia pulex. FoxO was silenced by RNA interference. The expression levels of the senescence-related genes FoxO , Akt , and Sir2 were analysed before and after interference by real-time polymerase chain reaction and Western blotting. Meanwhile, the production of an ephippium in D. pulex was evaluated before and after interference. The expression of FoxO and protein abundance decreased after interference. The number of ephippia produced in the Akt interference group was higher than in the two control groups, and the expressions of the senescence-related genes Akt and Sir2 decreased after interference. The results indicate that FoxO regulated senescence, primarily through the phosphorylation of Akt and acetylation of Sir2 , thereby affecting the reproductive transformation of D. pulex. [ABSTRACT FROM AUTHOR]

The embryonic stages of the anomopod Bosmina longirostris of the family Bosminidae were elucidated by scanning electron microscopy. Along with the corresponding stages of Bosmina coregoni described by Kotov (2001), these findings have enabled a comparison to Dunhevedia crassa , as a representative species of the family Chydoridae, and to Eurycercus lamellatus of the family Eurycercidae. In general, the developmental patterns are similar in these four species, particularly from blastulation to the first instar. The principal difference during embryogenesis is that in D. crassa and B. longirostris five thoracopods (six in E. lamellatus) are differentiated already with endo- and exopodites. [ABSTRACT FROM AUTHOR]

Thamnocephalidae, a family of Anostraca which is widely distributed on all continents of the world except Antarctica, currently consists of six genera and approximately 63 recognized species. The relationships among genera in Thamnocephalidae and the monophyly of Thamnocephalidae, determined using morphological characteristics or gene markers, remain controversial. In order to address the relationships within Thamnocephalidae, we sequenced Branchinella kugenumaensis mitogenomes and conducted a comparative analysis to reveal the divergence across mitogenomes of B. kugenumaensis. Using newly obtained mitogenomes together with available Anostracan genomic sequences, we present the most complete phylogenomic understanding of Anostraca to date. We observed high divergence across mitogenomes of B. kugenumaensis. Meanwhile, phylogenetic analyses based on both amino acids and nucleotides of the protein-coding genes (PCG) provide significant support for a non-monophyletic Thamnocephalidae within Anostraca, with Asian Branchinella more closely related to Streptocephalidae than Australian Branchinella. The phylogenetic relationships within Anostraca were recovered as follows: Branchinectidae + Chirocephalidae as the basal group of Anostraca and halophilic Artemiidae as a sister to the clade Thamnocephalidae + Streptocephalidae. Both Bayesian inference (BI)- and maximum likelihood (ML)-based analyses produced identical topologies. [ABSTRACT FROM AUTHOR]

The complete mitochondrial genome of Antarctic fairy shrimp Branchinecta gaini Daday, 1910 was sequenced, assembled and annotated using next-generation sequencing technology. The mitogenome of B. gaini is circular at 15,536 bp in length, consisting of 13 protein-coding genes, 23 tRNAs, two rRNAs and two major non-coding regions. In particular, there are two tRNA genes and one non-coding region between these two tRNA genes. A phylogenetic tree was constructed using concatenated amino acid sequences of 13 protein-coding genes. It reveals that B. gaini is clustered with the Anostraca group within the Branchiopoda clade. This study helps us understand the evolution of Anostraca. [ABSTRACT FROM AUTHOR]

The Daphnia longispina complex (Crustacea: Cladocera) contains several keystone freshwater species such as D. longispina O.F. Müller (D. rosea Sars is a junior synonym), D. galeata Sars, D. cucullata Sars, and D. dentifera Forbes. The complex is common throughout the Holarctic, but there are several geographic regions where local forms have been assigned to European species names based on a superficial morphological resemblance. Here we examine the species status of a form that was previously assigned to D. rosea from a montane bog pond on Honshu, Japan. We used two nuclear non-coding loci (nDNA), mitochondrial sequences (the ND2 protein-coding region) and morphology for evidence. The mitochondrial gene evidence supported the existence of a divergent lineage that is more closely related to D. galeata than to D. dentifera. However, morphology and the nuclear DNA data indicated a lineage that is most closely related to D. dentifera. As our evidence supported the existence of a cohesive divergent lineage, we described a new species, Daphnia japonica sp. nov. Recognition of local and subalpine diversity in this group is critical as ongoing anthropogenic disturbance has been associated with introductions, local extirpations, and hybridization. [ABSTRACT FROM AUTHOR]

Non-indigenous species may pose a threat to native ecosystems worldwide. In aquatic environments, invasives may have a negative impact on human food security and livelihoods. Several water fleas (Crustacea: Branchiopoda: Cladocera) are notorious invasive alien species influencing large freshwater lake systems and even inland seas. In the current review, we discuss the state of knowledge regarding non-indigenous species in the Cladocera and their invasiveness potential in different continents. We argue that the potential impacts and occurrence of cladoceran exotics may be higher than generally assumed. We critically review 79 cases from literature sources, involving 61 cladoceran taxa where records outside of their natural distribution ranges were previously interpreted as invasions. We assessed the probability of natural range expansions versus human-mediated introductions and we discuss several major corridors of invasion. We estimate human-mediated transportations for at least 43 taxa (out of 61; ca 70%), while other cases can be seen as natural expansions of their distribution ranges (not necessarily/not likely human-mediated) and/or taxonomical confusion. We confirm non-indigenous presence in recipient regions for at least 41 cladoceran taxa, of which several are true invasives (i.e., with negative impacts on native ecosystems). The majority are zooplankters with effects on pelagic freshwater ecosystems, yet we also report on introductions by littoral taxa. We argue that cryptic introductions of cladocerans are taking place on a global scale, yet they remain under the radar. We highlight several striking case studies, such as the Ponto–Caspian onychopods that have invaded the Baltic Sea and the Laurentian Great Lakes, and several clones of the anomopod genera Daphnia and Bosmina that have successfully colonised new environments, causing equilibria shifts in native aquatic worlds. At the same time, we dispel some myths about taxa that were misconstrued as invasive in certain localities. Based on our review, the first of its kind for freshwater zooplankton, future environmental monitoring tools including molecular techniques and detailed surveys with rigorous and critical taxonomical assessments may help to provide a clearer picture on the extent of invasiveness of cladocerans. [ABSTRACT FROM AUTHOR]

The fairy shrimp Tanymastigites ajjeri   n. sp. is described from a temporary water body, or guelta , in the Sahara Desert near the Tadrart mountains, east of Tassili n'Ajjer National Park, Libya. Males are readily separated from congeners by the morphology of the frontal appendages, which have an undivided lateral ramus and ≥ 0.4× the length of the medial ramus, and by the second antennae, in which the medial lamellar process bears a spatulate distal lobe. The new species is most similar to congeners T. perrieri (Daday, 1910) and T. mzabica (Gauthier, 1928), and it represents the sixth described species in this genus. We provide an updated key to the genus and comments on its diagnosis and definition, particularly concerning the descriptive terminology of the second antennae. In addition, we provide a list of new records of species of Branchiopoda, Copepoda, and Ostracoda from Tassili n'Ajjer National Park. [ABSTRACT FROM AUTHOR]

Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host–parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role. [ABSTRACT FROM AUTHOR]

Due to the lack of a taxonomic key for the identification of Artemia species, molecular markers have been increasingly used for phylogenetic studies. The mt COI marker is a regularly considered marker for the molecular systematics of Artemia populations. The proposed universal and specific primers have mostly failed to amplify the Artemia aff. sinica mt COI marker, and on the whole, the successfully amplified products of the PCR were inefficient, primarily through the representation of poly-peak or incomplete sequences. We presumed that if a forward primer could be developed regarding the joint regions of the last part of the previous gene (tRNA Tyr ) and the beginning of the target gene mt COI , the sequence could be relevant to the target-sequence of mt COI. Thus, here, we describe a new set of primers, which could be used to amplify the mt COI barcoding region of Artemia aff. sinica Cai, 1989, with a high performance of sequencing. The new primer set worked well also for other Artemia bisexual species, as well as for parthenogenetic populations. It is recommended that joint regions between the previous/next gene(s) and the target marker, could be aimed at when designing specific primers for other markers and taxa. Résumé: En raison de l'absence d'une clé taxonomique pour l'identification des espèces d' Artemia , les marqueurs moléculaires ont été de plus en plus utilisés pour les études phylogénétiques. Le marqueur mt CO est régulièrement considéré pour la systématique moléculaire des populations d' Artemia. Les amorces proposées, universelles ou spécifiques, ont la plupart échoué à amplifier le marqueur Artemia aff. sinica mt COI , et dans l'ensemble, les produits amplifiés avec succès par PCR ont été inefficients, principalement par la représentation de poly-pic ou de séquences incomplètes. Nous supposons que si une amorce anti-sens pouvait être développée pour les régions jointives de la dernière partie du gène précédent (tRNA Tyr ) et le début du gène cible mt COI , la séquence pourrait être pertinente de la séquence cible de mt COI. Ainsi, nous décrivons ici un nouvel ensemble d'amorces qui pourraient être utilisées pour amplifier la région du code-barre mt COI d' Artemia aff. sinica Cai, 1989, avec une performance de séquençage élevée. Ce nouvel ensemble d'amorces a bien fonctionné aussi pour les autres espèces bisexuelles d' Artemia , ainsi que pour les populations parthénogénétiques. Il est recommandé que la région de jonction entre les gènes précédents et suivants et le marqueur cible, pourrait être visée dans le design d'amorces spécifiques pour d'autres marqueurs ou taxa. [ABSTRACT FROM AUTHOR]

Artemia is the most common live food that is used in aquaculture worldwide. This study reports on biometrical variation in the cysts of the introduced, originally American Artemia franciscana from 24 non-native localities and two native habitats, in Asia and the U.S.A., respectively. The results show, that the largest diameter of untreated cysts, the largest diameter of decapsulated cysts, and a thicker chorion usually are found in invasive populations. Because of the small cysts, which have an effect on an increasing quantity per unit weight and thus could be the cause of increased hatching efficiency, commercial productions of A. franciscana cysts from native sources should potentially be considered higher quality than productions from non-indigenous environments. Principal Component Analysis revealed that all cyst batches from San Francisco Bay were classified in one group and most of the invasive populations could be arranged in another, separate group. Although the diameter of the decapsulated cyst and chorion thickness showed a negative and significant correlation among invasive populations, there was no significant relationship within native populations. These observations contrast with biometrical patterns of parthenogenetic populations. Résumé: Artemia est la nourriture vivante la plus utilisée mondialement en aquaculture. Cette étude porte sur la variation biométrique des cystes de l' Artemia franciscana américaine originelle provenant de 24 localités non–indigènes en Asie et deux habitats indigènes aux U.S.A. Les résultats montrent qu'un diamètre plus grand des cystes non traités, un diamètre plus grand des cystes décapsulés et un chorion plus épais sont généralement trouvés dans les populations invasives. Du fait que les petits cystes ont un effet sur l'augmentation de la quantité par unité de poids et ainsi pourraient être la cause d'une augmentation de l'efficacité de l'éclosion, les productions commerciales de cystes à partir de sources indigènes devraient être potentiellement considérées comme de meilleure qualité que les productions à partir d'habitats non indigènes. L'analyse des composants principaux a montré que les lots de cystes de la baie de San Francisco ont été classés en un seul groupe et que la plupart des populations invasives peuvent être arrangées ensemble dans un groupe séparé. Bien que le diamètre des cystes décapsulés et l'épaisseur du chorion aient montré une corrélation négative et significative chez les populations invasives, il n'y a pas d'interrelation parmi les populations indigènes. Ces observations contrastent avec les données biométriques des populations parthénogénétiques. [ABSTRACT FROM AUTHOR]

A study of the water fleas (Crustacea: Cladocera) in man-made lakes in the northeast part of the United Arab Emirates revealed five species: Ceriodaphnia cf. cornuta Sars, 1885; Daphnia (Ctenodaphnia) arabica Neretina, Al Neyadi et Hamza, 2022; Moina cf. micrura Kurz, 1875; Anthalona mediterranea (Yalim, 2005); Coronatella anemae Van Damme et Dumont, 2008. The morphologies of the four taxa are described in detail, except that of D. Arabica, which has been described previously. The phylogenies of the C. cornuta and M. micrura species groups were reconstructed based on sequences of the COI mitochondrial gene and the possible divergence age of the Arabian clades was estimated based on molecular clocks with paleontological calibration. We concluded that the C. cornuta complex was differentiated in the Upper Jurassic to Lower Cretaceous. The splitting off of clades containing the Arabian population took place during the Oligocene to Miocene. The M. micrura species group was differentiated in the Upper Cretaceous, and the splitting off of clades including Arabian populations took place around the Oligocene. Therefore, the clades (of different hierarchical orders) in the Arabian Peninsula are very old compared to clades of similar rank in northern Eurasia, which usually have Late Pleistocene history. Most of our sampled water bodies were newly constructed man-made reservoirs. As revealed, the phylogroups are locally distributed, and we hypothesized that they are colonists from surrounding natural water bodies inhabited by the relicts of older fauna that survived after the great climate aridization and then occupied newly available (man-made) biotopes. [ABSTRACT FROM AUTHOR]

The Daphnia longispina complex (Crustacea: Cladocera) contains several keystone freshwater species such as D. longispina O.F. Müller (D. rosea Sars is a junior synonym), D. galeata Sars, D. cucullata Sars, and D. dentifera Forbes. The complex is common throughout the Holarctic, but there are several geographic regions where local forms have been assigned to European species names based on a superficial morphological resemblance. Here we examine the species status of a form that was previously assigned to D. rosea from a montane bog pond on Honshu, Japan. We used two nuclear non-coding loci (nDNA), mitochondrial sequences (the ND2 protein-coding region) and morphology for evidence. The mitochondrial gene evidence supported the existence of a divergent lineage that is more closely related to D. galeata than to D. dentifera. However, morphology and the nuclear DNA data indicated a lineage that is most closely related to D. dentifera. As our evidence supported the existence of a cohesive divergent lineage, we described a new species, Daphnia japonica sp. nov. Recognition of local and subalpine diversity in this group is critical as ongoing anthropogenic disturbance has been associated with introductions, local extirpations, and hybridization.