Ostracod Species Research Articles

Late glacial and Holocene Ostracoda from the Melilla cold-water coral mound field

The ostracod assemblages from sediment core TTR17-401G recovered from the Melilla cold-water coral mound field in the eastern Alboran Sea spanning the last 13 ka are analysed quantitatively, taxonomically and palaeoecologically. The core can be subdivided in three distinct assemblages linked to environmental shifts during the Younger Dryas and the Bolling–Allerod interstadial. A total of 9 ostracod species is recorded, Paracypris polita is dominant throughout the core. Common accessory taxa Cytherella robusta, Echinocythereis vidua and Macromckenziea ligustica characterize the well-oxygenated ostracod assemblage 2 affected by the Younger Dryas. Favourable growth conditions for ostracods during the latter are indicated by large-sized Krithe praetexta specimens.

A strontium isotopic, petrographic, and Ostracoda biostratigraphic study of Middle-Late Miocene sequences: implications of record in the Silifke–Erdemli/Mersin, southern Turkey

In this paper, we present new data on Ostracoda micropaleontology, strontium isotopic ages, and petrology of the Miocene sequences in the Silifke–Erdemli area (Mersin/S. Turkey). Ostracods were investigated in the Middle and Late Miocene units, which are composed of clayey limestone and marl levels, reef limestones, and clay. Fifty-six ostracod species were identified, and a total of two initial levels were defined, one beginning in the Langhian stage, and the second at the end of the Serravallian and beginning of the Tortonian stage. The initial level of the Langhian stage is represented by the Carinocythereis, and the end of the Serravallian–beginning of the Tortonian stage is characterized by the initial level of Cyprideis. These levels have also been compared with other regions in the same stratigraphic levels in Turkey (Adana, Antakya, Mut, Denizli, and Antalya regions) and in areas around Turkey (Egypt, Italy, Greece, Croatia, and other Tethys–Paratethys regions). In addition, the levels identified in this study were also correlated to the planktonic foraminiferal zones identified for this region. The ostracod species identified are Carinocythereis at the initial level and subsequently, Cytherella postdenticulata Oertli, Grinioneis haidingeri minor (Ruggieri), Pokornyella deformis minor (Moyes), Carinocythereis antiquata (Baird), and Paracypris polita Sars; also, the other ostracod species are an initial level of Cyprideis followed by Cyprideis seminulum (Reuss), C. torosa (Jones), Cytheridea acuminata acuminata Bosquet, Miocyprideis sarmatica (Zalanyi), Neomonoceratina interiecta Bonaduce, Ruggieri, Russo and Bismuth, Schneidrella dromas (Schneider), and Krithe monosteracensis (Sequenza). Detailed petrographic analyses were carried out on the studied units. This analysis revealed that the reef limestones are composed of sandy intraclast-biomicrites, intra-packed biosparite, intra-packed biomicrite, microintra-packed micrite, and bioclastic-intramicrites; clayey limestones were rare clayey biomicrites and clayey intraclast-biomicrites. The main purpose of the study was to evaluate micropaleontological samples from the Miocene sequence based on ostracods and strontium dating to determine the precise age ranges. The 87Sr/86Sr ratios obtained from three samples of the limestones range between 0.708849 and 0.708902 and between 0.708868 and 0.708902, respectively. The Miocene sequences have been calibrated to range in age from 9.7 to 11.4 Ma via the strontium isotope ratio.

Karyotype Variability and Inter-Population Genomic Differences in Freshwater Ostracods (Crustacea) Showing Geographical Parthenogenesis.

Transitions from sexual to asexual reproduction are often associated with polyploidy and increased chromosomal plasticity in asexuals. We investigated chromosomes in the freshwater ostracod species Eucypris virens (Jurine, 1820), where sexual, asexual and mixed populations can be found. Our initial karyotyping of multiple populations from Europe and North Africa, both sexual and asexual, revealed a striking variability in chromosome numbers. This would suggest that chromosomal changes are likely to be accelerated in asexuals because the constraints of meiosis are removed. Hence, we employed comparative genomic hybridization (CGH) within and among sexual and asexual populations to get insights into E. virens genome arrangements. CGH disclosed substantial genomic imbalances among the populations analyzed, and three patterns of genome arrangement between these populations: 1. Only putative ribosomal DNA (rDNA)-bearing regions were conserved in the two populations compared indicating a high sequence divergence between these populations. This pattern is comparable with our findings at the interspecies level of comparison; 2. Chromosomal regions were shared by both populations to a varying extent with a distinct copy number variation in pericentromeric and presumable rDNA-bearing regions. This indicates a different rate of evolution in repetitive sequences; 3. A mosaic pattern of distribution of genomic material that can be explained as non-reciprocal genetic introgression and evidence of a hybrid origin of these individuals. We show an overall increased chromosomal dynamics in E. virens that is complementary with available phylogenetic and population genetic data reporting highly differentiated diploid sexual and asexual lineages with a wide variety of genetic backgrounds.

Cretaceous-Paleogene ostracods from the Paraíba Basin, northeastern Brazil

This work presents a detailed taxonomic study on the marine ostracods from the Paraíba Basin, northeastern Brazil, in wells from the wells Itamaracá-1IT-03-PE and Poty-1PO-01-PE, which record the Maastrichtian–Danian boundary. Besides the taxonomic data, this paper contributes to the paleoenvironmental knowledge of Cretaceous–Paleogene ostracods from the Paraíba Basin. The analysis of 98 samples of the well Itamaracá-1IT-03-PE and 59 samples of the Poty-1PO-01-PE resulted in the record of 34 ostracode species, all representative of a marine environment with normal salinity. Seven new species are proposed: Cytherella centrocompressa sp. nov.; Cytherella paraibensis sp. nov.; Neonesidea potyensis sp. nov.; Bythoceratina spinosa sp. nov.; Eucytherura ventrotuberculata sp. nov.; Langiella fauthi sp. nov. and Protobuntonia punctatum sp. nov.

Impact of seasonal changes in zooplankton biodiversity in Ukkadam Lake, Coimbatore, Tamil Nadu, India, and potential future implications of climate change

BackgroundZooplankton biodiversity serves as an ecological indicator of aquatic environment due to their rapid response according to environmental changes. At the present study, impact of seasonal changes on zooplankton biodiversity was conducted in the Ukkadam Lake (Lat 10° 59′ N and Long 76° 57′ E), at Coimbatore city, Tamil Nadu, India.ResultsThe biodiversity of zooplankton taxa were studied for a period from December 2011 to November 2012 on seasonal basis. During this time period, in total, 28 species of zooplankton were noticed, which includes 9 species of each Rotifera and Cladocera and 5 species of Copepoda and Ostracoda. In this present observation, total abundance of Rotifera was found to be predominant with 35%, followed by Cladocera 29%, Copepoda 29% and Ostracoda 7%. The population density of various group of zooplankton was observed, and it was found to be following order Rotifera > Copepoda > Cladocera > Ostracoda. The high and low population densities were recorded in summer and early monsoon season respectively. This higher zooplankton population density in summer might be due to the temperature acceleration in the Ukkadam Lake.ConclusionsThe present study revealed that zooplankton productivity was found to be higher in the Ukkadam Lake when the temperature was increased in summer season. It indicates that the temperature has influence on the zooplankton diversity. Therefore, increased temperature due to global climate change might have influence on the zooplankton production. Assessment of zooplankton biodiversity will be useful to monitor the health (water quality) and wealth (fishery productivity) of this lake system in the near future.

Nueva especie de ostrácodo del Plioceno de la Depresión del Guadalquivir (S.O. de España)

En este trabajo se describe e ilustra una nueva especie de ostrácodo, Cyprideis civisi nov. sp., procedente de sedimentos pliocenos de la Cuenca del Guadalquivir (S.O. de España). Esta nueva especie se caracteriza por su pequeño tamaño (longitud: < 820 μm; altura: < 460 μm) y por presentar valvas fuertemente reticuladas y un menor tamaño en comparación con otras de este género. Cyprideis civisi nov. sp. vivió en los sedimentos arenosos de un medio infralitoral, sometido a la acción de tormentas y de ocasionales flujos de aguas dulces. En este marco, esta especie formaba parte de la dieta de gasterópodos, como ponen en evidencia las huellas de bioerosión halladas en las valvas.

First report of ostracods (Crustacea) associated with Bithynian (Anisian, Middle Triassic) Tubiphytes‐microbial reef in the North Dobrogean Orogen (Romania)

AbstractThe Mahmudia Quarry is located in the North Dobrogean Orogen (Romania), representing the western tip of the Palaeotethys‐issued Cimmeride Orogenic System. One sample from the Tubiphytes‐microbial reef exposed in the quarry yielded an abundant well‐preserved ostracod assemblage of Bithynian, early Middle Anisian, Middle Triassic age. We report the occurrence of 56 ostracod species distributed among 23 genera. Ten species are newly described: Acratia caeracella sp. nov., Bairdia mandruella sp. nov., B. liviae sp. nov., Hungarella mahmudiaensis sp. nov., Kempfina tineriella sp. nov., Liuzhinia antalyaformis sp. nov., L. bithynica sp. nov., L. edvardgriegi sp. nov., Microcheilinella? contrariella sp. nov., Paracypris oanaella sp. nov. One species is renamed, Bairdia monostorii nom. nov. and the diagnosis of the genus Palaeocypridina is emended to include the central muscle scars pattern. The Tubiphytes ecosystem is complex with a multi‐layer food chain, as shown by the presence of diversified carnivorous nekto‐benthic ostracods, being both prey and predators of other organisms. The palaeoenvironmental requirements of the main ostracod taxa indicate a deposition in an open marine environment, on the outer platform‐upper slope zone, in accordance with information provided by other proxies. We discuss the relationship between ostracods and microbial mats during the Triassic and conclude that the composition of assemblages is related both to the characteristics of this chemosynthetically‐driven habitat and to bathymetry. However, some taxa, such as the genus Liuzhinia, are typical of Triassic microbial ecosystems. We perform the first analysis of ostracod provincialism during the Anisian and identify a distinct peri‐Palaeo‐Tethyan province.

Ostracods (Crustacea) as shelf to basin indicators: evidence from Late Devonian Yangdi and Nandong sections in Guangxi, South China

Abstract. Forty-eight ostracod species belonging to 28 genera from the Late Devonian of Guangxi in South China are described and figured. The ostracod assemblage from the Nandong section can be attributed to the rhenana–linguiformis conodont zones. The ecological assemblages of ostracods from the Yangdi section correspond to a smooth-podocopid association accompanied by some pelagic entomozoids. This mixed assemblage is indicative of an environment of carbonate platform to slope during an ongoing regression. The ostracod faunas from the Nandong section are on the contrary composed of both pelagic and benthic ostracods and pelagic forms dominate in number of specimens suggesting a basin environment.

Holocene Ostracoda (Crustacea) from the shallow Lake Vrana (Dalmatia, Croatia) and their paleoenvironmental significance

Lake Vrana in Dalmatia is a coastal karstic brackish water environment characterized by a high species richness of ostracods that evolved into their current morphologies during the Holocene. The results of this study reveal five ostracod zones within an 11 m sediment core taken from the central part of the lake. This sedimentary sequence reveals significant changes in both depositional and environmental conditions at local and regional scales; the oldest freshwater deposits, interpreted as the Late Pleistocene/Holocene transition, mainly comprise the species Candona neglecta, Juxilyocypris cf. schwarzbachi, Hungarocypris madaraszi, Darwinula stevensoni, and Mixtacandona sp. Although the lake had not formed at this time, it is well known that the living environment of most ostracod species is connected to flooded plains, marshes, rivers, springs, and interstitial waters. In the deepest and oldest sediments within the core, from depths between 1101 cm and 945 cm, the presence of C. neglecta and J. cf. schwarzbachi are indicative of cold water, while the dominant taxa at depths between 945 cm and 874 cm are the brackish species Cyprideis torosa and C. angulata, possibly suggesting the influence of seawater because of the presence of a permeable karstic ridge that separates the lake from the ocean. In contrast, the dominant ostracod taxa at depths between 874 cm and 813 cm are species typical of freshwater environments subject to colder climatic conditions indicating a marshy, low-energy wetland. We know that the first permanent freshwater body formed at about 8130 cal yr BP (a depth of 813 cm), while large proportions of Pseudocandona marchica, Heterocypris salina, D. stevensoni, and Metacypris cordata are all indicative of warmer, shallow waters that are rich in vegetation and have variable water level. Similarly, from 5240 cal yr BP onwards, a marine influence within the core is evidenced by the presence of Cy. torosa, while present lake water conditions (i.e., alternating seasonal changes in salinity from freshwater to brackish) were established by 2750 cal yr BP. The ostracod assemblages in sediments from Lake Vrana in Dalmatia have significant potential for reconstructing the evolution of this lake as well as for understanding environmental changes and rising sea level.

Palaeoenvironmental assessment of Early Cretaceous limnic ostracods from the Alagamar Formation, Potiguar Basin, NE Brazil

Source rocks from the Alagamar Formation were analysed and fifteen non-marine ostracod species and one foraminifer species were identified. Thecamoebians, gastropods, fish teeth and incertae sedis material also occurred. Among these fossils, an agglutinated foraminifer, Gaudryinella sp. aff. G. sherlocki, and occurrences of foraminiferal organic linings, indicate deposition under transitional marine (paralic) influence. Harbinia crepata is considered holoeuryhaline, Paracypria? elongata brackish stenohaline and the other ostracods are freshwater euryhaline. Limnocytheridae ostracods together with foraminifers occurred in intercalated beds, and this pattern of changes in associations is herein interpreted as a record of temporal changes, characteristic of transitional palaeoenvironments. Previous studies on biomarkers and some articles dealing with palynomorphs also suggest that at least part of this unit was deposited in lagoonal conditions.

Two new bairdiid ostracod species from the early Barremian–Hauterivian of the northern and central North Sea to the Atlantic margin off Norway

Abstract. Two new species of bairdiid Ostracoda are described from the lower Barremian – Hauterivian interval of the Valhall and Åsgard formations in the northern and central North Sea and Atlantic margin off Norway. The new species are Pontocyprella valhalla (lsid:zoobank.org:act:CA6B273F-CFF6-4C38-B9F4-18188225A711, 18 January 2018) and Bairdia asgarda (lsid:zoobank.org:act:4A4DC817-A028-45FB-9287-ABF3794F2FCB, 18 January 2018). These species dominate the ostracod assemblage that occurs abundantly in early Barremian–Hauterivian deep marine sediments of the northern and central North Sea and Haltenbanken area off Norway. Pontocyprella valhalla is restricted to this interval and because of its large size and distinct shape is a useful stratigraphic marker species, its last appearance being within the early Barremian.

Cold-seep ostracods from the western Svalbard margin: direct palaeo-indicator for methane seepage?

Abstract. Despite their high abundance and diversity, microfossil taxa adapted to a particular chemosynthetic environment have rarely been studied and are therefore poorly known. Here we report on an ostracod species, Rosaliella svalbardensis gen. et sp. nov., from a cold methane seep site at the western Svalbard margin, Fram Strait. The new species shows a distinct morphology, different from other eucytherurine ostracod genera. It has a marked similarity to Xylocythere, an ostracod genus known from chemosynthetic environments of wood falls and hydrothermal vents. Rosaliella svalbardensis is probably an endemic species or genus linked to methane seeps. We speculate that the surface ornamentation of pore clusters, secondary reticulation, and pit clusters may be related to ectosymbiosis with chemoautotrophic bacteria. This new discovery of specialized microfossil taxa is important because they can be used as an indicator species for past and present seep environments (http://zoobank.org/urn:lsid:zoobank.org:pub:6075FF30-29D5-4DAB-9141-AE722CD3A69B).

Scottoecia villosa sp. nov., a new deep-sea species of halocyprid (Ostracoda, Myodocopa) from the northern Pacific

Abstract A new species of halocyprid ostracod, Scottoecia villosa sp. nov., from the bathypelagic zone of the Kurile-Kamchatka Trench, is described and illustrated. This species is closely similar to S. foveolata (Deevey, 1968), but differs by the shape of the postero-dorsal corners of the carapace, the carapace sculpture, the number of secondary filaments on the first antenna, and the setae on the first endopodite segment of the maxilla. A key to the species of the genus Scottoecia is presented.

Les ostracodes plio-pléistocènes de la côte orientale de la Péninsule du Cap Bon (Tunisie)

This article concerns the study of the ostracods of the Upper Pliocene-Lower Pleistocene sedimentary deposits cropping out along the south-eastern coast of the Cape Bon Peninsula (Tunisia, Hammamet region, Sidi Khelas section). Fourteen samples were taken along a thirty-two-meters thick sedimentary silico-clastic series. Seventy species of ostracods belonging to twenty-four genera were found. The autochthonous association, which originally lived in an environment located in the infralittoral and upper circalittoral stages of the benthic marine domain, is cyclically affected by inputs from the more superficial environments due to the presence of relatively well-developed lagoon and/or estuary environments in the surrounding coastal areas. Within the ostracod association, the presence of Bythocythere turgida – a true “northern guest” – is particularly significant. This species indicates that these sediments were deposited during the cold phases of the Early Pleistocene. Among the ostracods found, those belonging to the families Trachyleberididae, Hemicytheridae and Bythocytheridae, which are dominant and include particularly significant species from the environmental and paleoclimatic point of view, are systematically recorded and commented on. Some species that are probably new have been described and photographed, but are currently left in open nomenclature because of how few specimens have been found.

Studies on Seasonal Zooplankton Community Structure of Gandak river

The selected sites of Gandak river near Sheetalpur ghat were studied for a period of one year from June 2013 to May 2014 for regular physico-chemical parameters and zooplankton community structure. The study was designed to estimate zooplankton abundance with seasonal repeated collections. The zooplankton community was composed of 08 species of Rotifera, 07 species of Cladocera, 02 species of Copepoda and 01 species of Ostracoda. These Crustaceans were dominant Class throughout the study period. The abundance of zooplankton in the pond follows a sequence as: Rotifera > Cladocera > Copepoda > Ostracoda. There changes in quantitative and qualitative community structure were found directly correlated with abiotic factors during study period.

On the relationship between the occurrence of ostracod species and elevation in Sakarya province, Turkey

On the relationship between the occurrence of ostracod species and elevation in Sakarya province, Turkey

Detailed biostratigraphic scales as based on the palaeobiogenetical approach (an example of the Upper Bajocian – Lower Bathonian ostracod scale of the Russian Platform)

Two new species of ostracods of the family Progonocytheridae Sylvester-Bradley Camptocythere (C.) lateres Tesakova et Shurupova, sp. nov. and C. (C.) angustius Tesakova et Shurupova, sp. nov. from the Michalskii and Besnosovi ammonite zones (Upper Bajocian – Lower Bathonian, Middle Jurassic) of the Sokur section (Saratov) are described. The changes in ontogenesis in the phylogeny of Camptocythere (C.) lateres Tesakova et Shurupova in the stratigraphical interval corresponding to the Palaeocytheridea kalandadzei ostracod Zone, and especially to the beds with C. (C.) lateres, have been studied. The levels of the change in the predominant type of sculpture (corresponding to evolutionary boundaries) are recognized in the sculpture development among the adult representatives of the species in its phylogeny. This palaeobiogenetic (heterochrony) approach allows subdivision of the beds with C. (C.) lateres into three stratigrapical intervals characterized by changes in the type of sculpture.

Palaeoenvironments during MIS 3 and MIS 2 inferred from lacustrine intercalations in the loess–palaeosol sequence at Bobingen (southern Germany)

Abstract. Recently exposed loess–palaeosol sequences in the northern Alpine foreland close to Bobingen (southern Germany) were investigated with a multi-proxy approach combining isotopic, geochemical, lithological, and micropalaeontological methods. Luminescence ages date the sections into the Middle and Upper Würmian periods corresponding to Marine Isotope Stages 3 and 2. A gleyic soil horizon at the base was dated to 45 ka and provided a palynoflora dominated by Poaceae, Cyperaceae, and Pinus, as well as frequent aquatic taxa. Lacustrine conditions prevailed after the gley formation until 30 ka, providing a comparatively diverse lacustrine fauna dominated by aquatic gastropods and the ostracod species Candona candida. At the transition to the Upper Würm, climatic conditions became harsh, indicated by accelerated deposition of more coarse-grained loess, organic geochemical indicators, and scarceness of biotic remains. Two tundra-gley horizons in the Upper Würm point to short phases of climatic amelioration with higher humidity also evidenced by reoccurrence of ostracod and aquatic gastropod remains. We propose that these climatic ameliorations were coincident with the Greenland interstadials 4 and 2.

Aquatic long-distance dispersal and vicariance shape the evolution of an ostracod species complex (Crustacea) in four major Brazilian floodplains

Cladogenesis is often driven by the interplay of dispersal and vicariance. The importance of long-distance dispersal in biogeography and speciation is increasingly recognised, but still ill-understood. Here, we study faunal interconnectivity between four large Brazilian floodplains, namely the Amazon, Araguaia, Pantanal (on Paraguay River) and Upper Paraná River floodplains, investigating a species complex of the non-marine ostracod genus Strandesia.We use DNA sequence data from the mitochondrial COI and the nuclear Elongation Factor 1 alpha genes to construct molecular phylogenies and minimum spanning networks, to identify genetic species, analyse biogeographic histories and provide preliminary age estimates of this species complex.The Strandesia species complex includes five morphological and eleven genetic species, which doubles the known diversity in this lineage. The evolutionary history of this species complex appears to comprise sequences of dispersal and vicariance events. Faunal and genetic patterns of connectivity between floodplains in some genetic species are mirrored in modern hydrological connections. This could explain why we find evidence for (aquatic) long-distance dispersal between floodplains, thousands of kilometres apart. Our phylogenetic reconstructions seem to mostly indicate recent dispersal and vicariance events, but the evolution of the present Strandesia species complex could span up to 25 Myr, which by far exceeds the age of the floodplains and the rivers in their current forms.

Distribution and Taxonomy of Shallow Marine Ostracods from the Western Coast of the Red Sea, Egypt

A total 5849 individuals of ostracods constituting twenty species were collected from five shallow marine sites along the area from El-Quseir to Marsa Alam on the West Coast of the Red Sea. The twenty ostracod species belonging to sixteen genera and ten different families. The three genera; Loxoconcha, Neonesidea and Xestoleberis have high species diversity. Furthermore, the species Loxoconcha ghardaqensis, Xestoleberis rotunda, Paranesidea fracticorallicola, Tanella gracilis and Neonesidea schulzi were the best recognized in the collecting region. Otherwise, the distribution of the collected ostracod species in relation to environmental variables and plants were discussed in detail here. Based on this, it is concluded that, vegetation type appears to be the most important factor controlling the distribution of ostracod species in the investigated area. Also, other factors such as, water temperature, salinity, dissolved oxygen, pH and electrical conductivity play an important role. Scanning electron microscope images of valves are delivered of the recorded taxa. These fauna displays close affinities to those of the Red Sea and the Indo- Pacific region.