A new species of the genus Ceriodaphnia Dana, 1853 (Cladocera: Daphnidae) from Eastern Siberia (Russia) that combines morphological features of two species groups.

Taxa of the genus Ceriodaphnia Dana, 1853 (Cladocera: Daphniidae) are ubiquitous in temperate and tropical lakes, and the taxonomy of the genus is confused. Moreover, present keys are often regional and insufficient for the taxonomic assignment of species at a global scale. This communication is aimed at improving our understanding of the C. dubia s.l. species group. We redescribe C. dubia s.l. from Northern Eurasia and describe a new species from Central Yakutia (Eastern Siberia, Russia). In contrast to typical members of the C. dubia group, C. nikolaii sp.nov. has the postabdomen of the parthenogenetic female with preanal margin slightly or strongly projecting and angulated. Moreover, adult males have a pronounced preanal angle and sensory seta of antenna I which is shorter than the longest easthetasc. Our finding challenges current definitions of species groups in Ceriodaphnia. Indeed, a postabdomen shape with a strongly projected preanal angle is characterstic of another group of this genus, namely the C. laticaudata-group. We found a taxon that combines the diagnostic morphological characters of two species groups. Further development of the genus taxonomy must be accompanied by redescriptions of all well-accepted and dubious taxa from their type localities and revisions of populations from other localities of the world.

Genome Assembly of a Relict Arabian Species of Daphnia O. F. Müller (Crustacea: Cladocera) Adapted to the Desert Life.

The water flea Daphnia O.F. Müller 1776 (Crustacea: Cladocera) is an important model of recent evolutionary biology. Here, we report a complete genome of Daphnia (Ctenodaphnia) arabica (Crustacea: Cladocera), recently described species endemic to deserts of the United Arab Emirates. In this study, genome analysis of D. arabica was carried out to investigate its genomic differences, complexity as well as its historical origins within the subgenus Daphnia (Ctenodaphnia). Hybrid genome assembly of D. arabica resulted in ~116 Mb of the assembled genome, with an N50 of ~1.13 Mb (BUSCO score of 99.2%). From the assembled genome, in total protein coding, 5374 tRNA and 643 rRNA genes were annotated. We found that the D. arabica complete genome differed from those of other Daphnia species deposited in the NCBI database but was close to that of D. cf. similoides. However, its divergence time estimate sets D. arabica in the Mesozoic, and our demographic analysis showed a great reduction in its genetic diversity compared to other Daphnia species. Interestingly, the population expansion in its diversity occurred during the megadrought climate around 100 Ka ago, reflecting the adaptive feature of the species to arid and drought-affected environments. Moreover, the PFAM comparative analysis highlights the presence of the important domain SOSS complex subunit C in D. arabica, which is missing in all other studied species of Daphnia. This complex consists of a few subunits (A, B, C) working together to maintain the genome stability (i.e., promoting the reparation of DNA under stress). We propose that this domain could play a role in maintaining the fitness and survival of this species in the desert environment. The present study will pave the way for future research to identify the genes that were gained or lost in this species and identify which of these were key factors to its adaptation to the harsh desert environment.

Daphnia japonica sp. nov. (Crustacea: Cladocera) an eastern Palearctic montane species with mitochondrial discordance.

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.

A redescription of the Mediterranean endemic cladoceran Daphnia chevreuxi Richard, 1896 (Cladocera: Daphniidae).

The Mediterranean area is a biodiversity and endemism hotspot. Circum-Mediterranean taxa are known among different hydrobionts, including the water fleas. Some Mediterranean endemic cladoceran taxa have been described or redescribed according to modern taxonomical standards, but accurate drawings are missing for others. Here we redescribe the Mediterranean endemic Daphnia chevreuxi Richard, 1896 (Crustacea: Cladocera) and briefly review available data on its distribution and ecology. The species is confirmed to be a typical inhabitant of the temporary ponds of the central Mediterranean area, whereas its populations from the eastern Balkans and the Middle East should be studied in order to check for their actual identity. We conclude that the Mediterranean area is an example of a well-studied region as Cladocera are concerned, but the study of other regions is necessary in order to understand better the cladoceran diversity and distribution patterns in Eurasia.

A new species of Coronatella Dybowski amp; Grochowski, 1984 (Cladocera: Chydoridae) endemic to Jeju Island (Republic of Korea).

Recently particular attention of cladocerologists has focussed on a subtropical-southern temperate zone of the Far East of Eurasia comprising a center of water flea (Crustacea: Cladocera) endemism. Two endemic taxa were described previously from Jeju Island (Republic of Korea), but still the cladocerans of this island are poorly known. The aim of this communication is to describe a new species of Coronatella (Coronatella) Dybowski Grochowski, 1894 (Anomopoda: Chydoridae) and discuss diagnostic characters of this taxon with reference to their diagnostic value in other cladoceran groups. Surprisingly, all characters discriminating C. (C.) jejuana sp. nov. from closest C. (C.) rectangula (Sars, 1862) are from the set suggested for chydorid species delimitation by Nikolai Smirnov more than 50 years ago. Therefore, a search for diagnostic characters of a potentially new taxon could concentrate on just some potentially important structures. However, a program of detailed redescriptions of previously established taxa is necessary for an adequate description of new taxa which are congeners of the former, and such comprehensive work is still in its infancy.

A new redescription of Daphnia pusilla (Serventy, 1929) (Cladocera: Daphniidae) with emphasis on the thoracic limbs of Daphnia (Ctenodaphnia) Dybowski amp; Grochowski, 1895.

The genus Daphnia O.F. Mller, 1776 (Crustacea: Cladocera) still has a confused taxonomy for several objective and subjective reasons. Still there are many taxa with inadequately described morphology, primarily among the subgenus Daphnia (Ctenodaphnia) Dybowski Grochowski, 1895. We provide a redescription of an Australian endemic taxon Daphnia (Ctenodaphnia) pusilla (Serventy, 1929) according to recent standards of morphological study with special attention to the thoracic limbs. We conclude that main differences between thoracic limbs of the subgenera D. (Ctenodaphnia) and Daphnia s. str. concern the limb I only as it is well-known among the cladocerans of other families. But still only a few species of D. (Ctenodaphnia) have been studied adequately, and efforts to redescribe their morphology need to be continued.

On the taxonomic status of Oriental populations of the genus Bosminopsis Richard, 1895 (Crustacea: Cladocera).

It is widely accepted among the Cladocera (Crustacea) taxonomists that almost all cosmopolitan taxa are represented by some un-revised complexes of cryptic species. But many macro taxa of the cladocerans are still unrevised. The aim of this work is to analyze the taxonomic status of Oriental populations of the genus Bosminopsis Richard, 1895 (Anomopoda: Bosminidae) based on morphological characters. We have studied populations from India, Myanmar, Cambodia, Thailand, Laos, Vietnam, Philippines, Malaysia and Papua New Guinea and concluded that Oriental populations belong to a single species, Bosminopsis africanus (Daday, 1908), initially described from Africa. Analysis of literature data confirms that is widely distributed through whole Oriental zone. A single large mucro, or the mucro accompanied by an additional small spine in both sexes, is the main trait which differentiates B. africanus from B. zernowi Linko, 1901 distributed in more northern regions of Eurasia.

Mitogenomics of Cladocera (Branchiopoda): Marked gene order rearrangements and independent predation roots.

Cladocera (Crustacea: Branchiopoda) is a key group of invertebrates. Despite a long history of phylogenetic research, relationships within this group remain disputed. We here provide new insights based on 15 new mitochondrial genomes obtained from high-throughput sequencing (HTS) and 40 mitogenomes extracted from published HTS datasets. Together with 25 mitogenomes from GenBank, we generated a matrix of 80 mitogenomes, 44 of them belonging to Cladocera. We also obtained a matrix with 168 nuclear orthologous genes to further assess the phylogenetic result from mitogenomes based on published data and one new HTS data ofLeptodora. Maximum likelihood and Bayesian phylogenetic analyses recovered all Branchiopoda orders as monophyletic and supported a sister-group relationship between Anomopoda and Onychopoda, making the taxon Gymnomera paraphyletic and supporting an independent origin of predatory Haplopoda and Onychopoda. The nuclear phylogeny and topological tests also support Gymnomera as paraphyletic, and the nuclear phylogeny strongly supports a sister-group relationship between Ctenopoda and Haplopoda. We provide a fossil-calibrated time tree, congruent with a Carboniferous origin for Cladocera and a subsequent diversification of the crown group of Anomopoda, Onychopoda, and Ctenopoda, at least in the Triassic. Despite their long evolutionary history, non-Cladoceran Branchiopoda exhibited high mitogenome structural stability. On the other hand, 21 out of 24 gene rearrangements occurred within the relatively younger Cladocera. We found the differential base compositional skewness patterns between Daphnia s.s. and Ctenodaphnia, which might be related to the divergence between these taxa. We also provide evidence to support the recent finding that Spinicaudata possesses mitogenomes with inversed compositional skewness without gene rearrangement. Such a pattern has only been reported in Spinicaudata.

A new species of Bosmina (Liederobosmina) Brték, 1997 (Cladocera: Bosminidae) from high mountain lakes of Colombia.

Insufficient attention has been recently paid by the taxonomists to the family Bosminidae Baird (Crustacea: Cladocera). Here we describe a new species of Bosmina (Liederobosmina) Brték from high mountain water bodies of Colombia which is unique among all bosminids having heavily striated valves. Most probably, this taxon has a narrow distribution area in the Andean high mountains. It is obvious that the Andean highlands must be studied in detail, i.e. using molecular methods, and more new taxa might be detected in the future.

Bosminopsis deitersi (Crustacea: Cladocera) as an ancient species group: a revision.

Water fleas (Crustacea: Cladocera) of the Family Bosminidae have been studied since the founding of paleolimnology and freshwater ecology. However, one species, Bosminopsis deitersi, stands out for its exceptional multicontinental range and broad ecological requirements. Here we use an integrated morphological and multilocus genetic approach to address the species problem in B. deitersi. We analyzed 32 populations of B. deitersi s. lat. Two nuclear and two mitochondrial loci were used to carry out the bGMYC, mPTP and STACEY algorithms for species delimitation. Detailed morphological study was also carried out across continents. The evidence indicated a widely distributed cryptic species in the Old World (Bosminopsis zernowi) that is genetically divergent from B. deitersi s.str. We revised the taxonomy and redescribed the species in this complex. Our sampling indicated that B. zernowi had weak genetic differentiation across its range. A molecular clock and biogeographic analysis with fossil calibrations suggested a Mesozoic origin for the Bosminopsis deitersi group. Our evidence rejects the single species hypothesis for B. deitersi and is consistent with an ancient species group (potentially Mesozoic) that shows marked morphological conservation. The family Bosminidae, then, has examples of both rapid morphological evolution (Holocene Bosmina), and morphological stasis (Bosminopsis).

Unexpected mitochondrial lineage diversity within the genus Alonella Sars, 1862 (Crustacea: Cladocera) across the Northern Hemisphere.

Representatives of the genus Alonella Sars (Crustacea: Cladocera: Chydorinae) belong to the smallest known water fleas. Although species of Alonella are widely distributed and often abundant in acidic and mountain water bodies, their diversity is poorly studied. Morphological and genetic approaches have been complicated by the minute size of these microcrustaceans. As a result, taxonomists have avoided revising these species. Here, we present genetic data on Alonella species diversity across the Northern Hemisphere with particular attention to the A. excisa species complex. We analyzed 82 16S rRNA sequences (all newly obtained), and 78 COI sequences (39 were newly obtained). The results revealed at least twelve divergent phylogenetic lineages, possible cryptic species, of Alonella, with different distribution patterns. As expected, the potential species diversity of this genus is significantly higher than traditionally accepted. The A. excisa complex is represented by nine divergent clades in the Northern Hemisphere, some of them have relatively broad distribution ranges and others are more locally distributed. Our results provide a genetic background for subsequent morphological analyses, formal descriptions of Alonella species and detailed phylogeographical studies.

The Explanatory Effect of a Label: Its Influence on a Category Persists Even If We Forget the Label.

In this study we replicated the explanatory effect of a label which had been found by Giffin et al. (2017). In their experiments, they used vignettes describing an odd behavior of a person based on culturally specific disorders that were unfamiliar to respondents. It turned out that explanations which explain an odd behavior through a person's tendency to behave that way (circulus vitiosus) seemed more persuasive if the disorder was given a label that was used in the explanation. We replicated these results in Experiment 1, and in a follow-up Experiment 2 we examined the familiarity with category information and the evaluation of that category over time (the delay lasted one week). We realized that the label effect persists even when people make judgments based on their recollections about a category. Furthermore, according to a content analysis of the recollections, participants in the label condition remembered more information from the vignettes but tended to forget an artificial label; however, they used other words from the disorder domain instead (like "disease" or "kleptomania"). This allowed us to suggest a new interpretation of this effect: we suppose that in the Giffin et al. (2017) experiments the label did not bring any new features to a category itself, but pointed to a relevant domain instead, so the effect appeared from the activation of areas of knowledge in semantic memory and the application of relevant schema for learning a new phenomenon.

Partial revision of the neustonic genus Scapholeberis Schoedler, 1858 (Crustacea: Cladocera): decoding of the barcoding results.

Water fleas (Crustacea: Cladocera) are among the most intensively studied freshwater invertebrates. However, ecologically important daphniids that live on the surface layer (neuston) remain taxonomically confused. Here we attempt to reconcile genetic and morphological information for the neustonic genus Scapholeberis Schoedler, 1858 (Cladocera: Daphniidae) and present the first revision of the Scapholeberis kingii species group. We analyzed new and existing mitochondrial DNA sequences (сytochrome C oxidase subunit I gene region) together with morphology for all but one of the known species of the neustonic daphniids. Morphological comparisons of available populations, belonging to the Scapholeberis kingii species group from several Australian, Asian and African localities, revealed, that they are almost identical according to parthenogenetic females. However, Australian populations can be reliably distinguished from Asian ones based on the morphology of gamogenetic females. Mitochondrial DNA data analyses revealed divergent lineages (>17% for the DNA barcoding COI region) for the three different species (Australia, Asia and Africa). Based on this set of data, we redescribed S. kingii Sars, 1888 from Australia, its terra typica, and described a new species, S. smirnovi sp.nov. from the Russian Far East, Korea and Japan. The status of populations from Ethiopia and the Republic of South Africa remained unclear, because in the African material and the putative type material, we found only parthenogenetic females. Our results provide an integrative revision of the S. kingii species group and improve the taxonomic scaffold used for barcoding and genomics for the remaining species groups in the daphniid genus Scapholeberis.

Priority of Carl Linnaeus as the author of the oldest species of Cladocera (Crustacea: Branchiopoda): Daphnia pulex (Linnaeus, 1758) and Polyphemus pediculus (Linnaeus, 1758).

In taxonomy, it is important to maintain chronological order in taxon naming and understanding. Here, I confirm that according to the rules of Zoological Nomenclature, Carl Linnaeus must be regarded as the author of two common cladoceran taxa, Daphnia pulex (Linnaeus, 1758) and Polyphemus pediculus (Linnaeus, 1758). Both were established in the 10th Edition of "Systema Naturae", the starting point of Zoological Nomenclature. The history of these taxa is described.

A new species of the Daphnia sinevi group (Crustacea: Cladocera: Daphniidae) from Sakhalin Island, Russian Far East.

Daphnia curvirostris species complex is a cladoceran group (Crustacea: Cladocera) with maximum diversity in Eastern Palearctic. To date, several representatives of this complex are known from the Russian Far East. Here we describe a new species of the Daphnia sinevi species group from water bodies of Sakhalin Island. Morphology of its parthenogenetic females is similar to that in D. sinevi from the continental part of Asian Eurasia. However, we found diagnostic traits of D. sakhalinensis sp.nov. in morphology of the second pecten on postabdominal claw, armature of seta 2 on exopodite III, proportions of setae 1/ and 2 length on exopodite V, relative length of male rostrum and structure of the second pecten of male postabdominal claw. This work contributes to our full revision of the D. curvirostris species complex. Separation between continental and Sakhalin populations of D. sinevi group probably happened in Pliocene (about 5 MA) when Sakhalin began to separate from the mainland. However, we cannot exclude a version that populations of D. sakhalinensis sp.nov. appeared as a result of colonization of Sakhalin from the continent and further independent evolution of the island populations.

Position of Moina wierzejskii Richard, 1895 (Crustacea: Cladocera) within the genus Moina Baird, 1850 in the light of new morphological data.

The family Moinidae (Crustacea: Cladocera) is intensively studied recently. Last genetic investigations revealed a huge diversity of species in the genus Moina Baird, 1850, comparable with the number of species in the genus Daphnia O.F. Müller, 1776. However, unlike daphniids, the taxonomy of moinids is understudied. Along with new still undescribed species, there are many inadequately described and illegitimately forgotten taxa within Moinidae. Moinids of tropical and subtropical regions remain especially poorly studied, and their features are ignored in recent intergeneric systems. Here we redescribe the morphology of M. wierzejskii Richard, 1895, a peculiar Moina from the New World, and discuss its position within the genus Moina s.l. In the taxonomic scheme, designed for European moinids, M. wierzejskii takes an intermediate position between subgenera Exomoina Hudec, 2010 and Moina s.str. Similarly to European species belonging to M. (Exomoina), females of M. wierzejskii have a modified Ilyocryptus-like labrum and an ephippium with two resting eggs. However, the males have no exopod on the thoracic limb I which suggests that this species is closer to the subgenus Moina s.str. The lack of exopod on male thoracic limb I was also marked in another species of the genus from the New World, M. hutchinsoni Brehm, 1937. To date such unusual combination of morphological features is unknown for any moinids from the Old World and Australia. We hope that our observations will stimulate deep phylogenetic studies of peculiar moinids inhabiting the New World.

A new North Eurasian species of the Alona affinis complex (Cladocera: Chydoridae).

Our analysis of Alona cf. affinis (Cladocera: Chydoridae) populations from European Russia, Siberia and Far East of Russia bearing denticles at the posteroventral corner, based on both their morphology and genetic study considering variability of mitochondrial COI and 16S and nuclear 18S genes, revealed that they belong to a separate taxon described here as Alona sibirica sp. nov. Previously populations with denticles at the posteroventral corner were recorded from Sweden, Finland, Ukraine, European Russia, Kyrgyzstan and Mongolia, but never reported outside the temperate regions of Eurasia, so A. sibirica sp. nov. is presumably the only species of the A. affinis group with denticles at the posteroventral corner of the valves. The primary distribution area of the new species is North-East Palaearctic, while Eastern Europe and Central Asia are the areas of the species penetration, where it is less common and frequently coexisting with A. affinis s. str.

The Intercontinental phylogeography of neustonic daphniids.

Organisms that live at the freshwater surface layer (the neuston) occupy a high energy habitat that is threatened by human activities. Daphniids of the genera Scapholeberis and Megafenestra are adapted to the neuston but are poorly studied for biogeography and diversity. Here we assess the global phylogeography of neustonic daphniids. We obtained 402 new multigene sequences from the 12S rRNA, 16S rRNA, and tRNA (val) regions of the mitochondrial genomes of daphniids from 186 global sites. We assessed the intercontinental origins and boundaries of mitochondrial lineages and the relative rates of evolution in neustonic and planktonic daphniids. We identified 17 divergent lineages in the neustonic daphniids that were associated with biogeographic regions. Six of these lineages had intercontinental ranges - four of these were Transberingian. Patagonian populations of Scapholeberis rammneri were monophyletic and nested within a closely related clade of western North American haplotypes, suggesting an introduction from the Western Nearctic to South America. The Eastern Palearctic was more diverse than other regions, containing eight of the major lineages detected in the Scapholeberinae. The Genus Scapholeberis had high levels of divergence compared to non-neustonic daphniids. Neustonic daphniids have more divergent biogeographic lineages than previously appreciated.

Crustacean remains from the Yuka mammoth raise questions about non-analogue freshwater communities in the Beringian region during the Pleistocene.

Frozen permafrost Pleistocene mammal carcasses with soft tissue remains are subject to intensive study and help elucidate the palaeoenvironment where these animals lived. Here we present an inventory of the freshwater fauna and flora found in a sediment sample from the mummified Woolly Mammoth carcass found in August 2010, from the Oyogos Yar coast near the Kondratievo River in the Laptev Sea region, Sakha (Yakutia) Republic, NE Russia. Our study demonstrates that the waterbody where the carcass was buried could be characterized as a shallow pond or lake inhabited mainly by taxa which are present in this area today, but additionally by some branchiopod crustacean taxa currently absent or unusual in the region although they exist in the arid zone of Eurasia (steppes and semi-deserts). These findings suggest that some "non-analogue" crustacean communities co-existed with the "Mammoth fauna". Our findings raise questions about the nature of the waterbodies that existed in Beringia during the MIS3 climatic optimum when the mammoth was alive.

A new case of false "wide" distribution for tropical cladocerans: the genus Notoalona Rajapaksa amp; Fernando, 1987 (Crustacea: Cladocera) in the Old World.

Members of the genus Notoalona Rajapaksa Fernando, 1987 (Cladocera: Chydoridae: Aloninae) are small-sized chydorids, inhabiting tropical water bodies around the World. Based on morphological features two species, N. globulosa (Daday, 1898) and N. pseudomacronyx Van Damme, Maiphae Sa-Ardrit, 2013, were revealed in tropical Asia, but the status of African populations has remained unclear for a long time. Some authors identified African specimens as N. globulosa, others considered them as potentially new species awaiting description. Here we reexamined morphology of Notoalona populations from tropical Asia (Thailand, Laos) and Africa (Ethiopia, Kenya, Sudan and Madagascar). Although parthenogenetic females from Asia and Africa are basically similar, a single stable difference was found. In N. globulosa, the length of the basal spine and claw base are almost equal to each other, while in all investigated African specimens the basal spine is two times longer than base of postabdominal claw. This feature allows us to identify African populations as N. pseudomacronyx. Length of the setules in the basal group near the postabdominal basal spine, which was previously discussed in the literature as a specific feature for African populations, in fact, is overly variable and cannot be considered as diagnostic characteristic for the description of African populations as a separate taxon. Thus, the distribution range of N. pseudomacronyx is hereby expanded from South Africa to South East Asia, while N. globulosa s.l. occupies water bodies from tropical Asia to Australia. The same distribution patterns, when sibling species occur together in tropical Asia, have been shown for some other cladocerans as well. No doubt, the Asian tropics may be a particularly interesting area for future investigations on co-occurrence of sibling cladocerans, their ecology, behavior, genetics and potential hybridization.