L'ornementation chez l'ostracode Phalcocythere du Pakockne: résultat d'une action morphogéne antagoniste?

Les relations spatiales liant la désorganisation des rangées de fossettes en relation avec le développement des tubercules et des épines chez quatre morphes de Phalcocythere cultrata (Apostolescu, 1961) et deux morphes de Phalcocythere vesiculosa (Apostolescu, 1961) suggérent la possibilité d'une action neurosécrétrice sous la dépendance d'un ou de plusieurs génes à action antagoniste. Une extension de ce mécanisme supposé est proposée chez quelques Trachyle-berididae dans une perspective évolutive. □ Ornementation, paléogénétique, polymorphisme, Niger, ostracode.
Disorder in the organization of the rows of pits in relation to the development of tubercles and spines is analyzed in four morphotypes of Phalcocythere cultrata (Apostolescu, 1961) and two morphotypes of Phalcocythere vesinclosa (Apostolescu, 1961). This spatial linkage suggests the possibility of a neurosecretory effect controlled by one or several genes operating interactively. This hypothesis is applied to the interpretation of evolutionary patterns in some Trachyle-berididae. □ Ornament, paleogenetics, polymorphism, Niger Republic, ostracod.     

Ordovician (Dobrotivá Formation) ostracodes and trilobites from Ejpovice (Bohemia) and their relations to faunas of northern and western Europe

For the first time a complete ostracode and trilobite fauna is described from the Dobrovitá Formation (Ordovician) of Perunica. In contrast to the trilobite fauna the ostracode fauna evidences close relations to both Armorica and Baltica. The trilobite fauna comprises 11 species out of 11 genera, the ostracode fauna comprises 15 (5 new) species out of 15 (1 new) genera.     

Ostracodes bathyaux du Crétacé terminal - Éocène moyen en Atlantique tropical (Plateau de Demerara, Leg 207)

Ostracode faunal assemblages which lived in bathyal environments are analysed from uppermost Maastrichtian - middle Eocene sediments of sites 1260 and 1261, drilled on the distal margin of Demerara, off Surinam (Leg 207, western tropical Atlantic). As for numerous other groups, the Cretaceous/Tertiary mass extinction event led to the disappearance of numerous bathyal ostracode species and it was followed by a very slow recovery during the Palaeocene. It appears that this extinction event was more devastating for detritus-feeder ostracode species than for filter or silt-eater groups, which crossed the K/T boundary without any or little morphological change. This extinction selectivity may be explained by the drop in productivity of surface waters which took place at the K/T boundary. Finally, psychrospheric ostracode species were encountered in Middle Eocene sediments, confirming thus the general cooling of deep oceanic realm recognised in general for this time interval.     

THE NEW GENUS COPELANDELLA FROM THE CARBONIFEROUS — THE YOUNGEST KNOWN BEYRICHIACEAN OSTRACODES

A palaeocope ostracode with prominent cruminal dimorphism occurs in Lower Carboniferous strata of Nova Scotia and Ireland. It is believed to be the youngest representative of the Beyrichiidae Matthew 1886, a family hitherto only known from the Silurian and Devonian. Because of differences in lobation and adventral structures this ostracode is here assigned to the new genus Copelandelia. The occurrence of the type species Copelandelia novascotica in strata of comparable age (Viséan) in Nova Scotia and Ireland appears to add some support to the hypothesis that North America and Europe formed one supercontinent in the Paleozoic, since this species is assumed to have lived in a near-shore, or even a brackish or non-marine environment.     

New lower Callovian ostracodes from the Kursk Region

Lower Callovian deposits (subpatruus and koenigi ammonite zones) in the Mikhailovskii Mine section (Central Russia, Kursk Region) yielded 13 ostracode species (two of them are new) belonging to ten genera. This ostracode assemblage corresponds to ostracode beds with Praeschuleridea wartae-Pleurocythere kurskensis. The stratigraphic range of these beds corresponds to three ammonite biohorizons: Chamoussetia crobyloides, Kepplerites gowerianus gowerianus, and K. indigestus. Three distinct ostracode assemblages have been defined in the section based on their taxonomy and occurrence pattern. Two new species, Pleurocythere kurskensis sp. nov. and Pseudohutsonia wienholzae sp. nov., are described.     

Intertidal meiofaunal biodiversity with respect to different algal habitats: a test using phytal ostracodes from Southern California

Rocky intertidal algae harbor a diverse invertebrate meiofauna of arthropods, nematodes and other invertebrates. Despite its ecological importance, relatively little is known about the diversity and composition of this important component of intertidal biodiversity. In this study, we quantified species composition, abundance and distribution of ostracodes, an important group of phytal meiofauna, at two different intertidal areas in southern California. In total, we recovered 22 ostracode species from three different orders (16 podocopids, five myodocopids and one platycopid), nearly a quarter of which could not be assigned to existing taxa. The abundance of ostracodes differed significantly among algal types, with structurally complex algae bearing many more ostracodes per gram of algae than simple forms (blade-like algae and the surfgrass Phyllospadix). Although most ostracode species were recovered from multiple kinds of algae, different algae harbored distinct assemblages that could be discriminated statistically on the basis of relative abundances of ostracode species. This segregation of the ostracode fauna according to algal species is evident even over very short spatial scales (<1 m). Finally, ostracode samples from turf-forming algae were more species rich than samples from other kinds of macroalgae. Since turf-forming algae are easily damaged by human trampling, this component of ostracode biodiversity may be particularly vulnerable to anthropogenic impacts on the intertidal habitat. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: K. Martens     

Find of Tremadocian ostracodes in cherts of Kazakhstan

First late Tremadocian (Early Ordovician) ostracodes were found in cherts of the Burubaital Formation near the “Burultas” deposit in southern Kazakhstan. The preservation of carbonate ostracode shellshells in siliceous environment is discussed. The monotypic ostracode assemblage includes the newly described form, Burultalina nikitinae gen. et sp. nov.     

Salinity tolerance of three ostracode species (Crustacea:Ostracoda) of Iberian saline lakes

Laboratory experiments and field data were used to determine salinity tolerance limits of three ostracode species (Prionocypris aragonica, Eucypris mareotica and Heterocypris barbara) from Iberian saline lakes. Salinity tolerance appeared related to ionic composition and temperature. Implications for ostracode ecology and geographical distribution are evaluated.     

High intraspecific genetic divergence in the versatile fairy shrimp <Emphasis Type="Italic">Branchinecta lindahli</Emphasis> with a comment on cryptic species in the genus <Emphasis Type="Italic">Branchinecta</Emphasis> (Crustacea: Anostraca)

A new Arctic Ostracode Database-2015 (AOD-2015) provides census data for 96 species of benthic marine Ostracoda from 1340 modern surface sediments from the Arctic Ocean and subarctic seas. Ostracoda is a meiofaunal, Crustacea group that secretes a bivalved calcareous (CaCO₃) shell commonly preserved in sediments. Arctic and subarctic ostracode species have ecological limits controlled by temperature, salinity, oxygen, sea ice, food, and other habitat-related factors. Unique species ecology, shell chemistry (Mg/Ca ratios, stable isotopes), and limited stratigraphic ranges make them a useful tool for paleoceanographic reconstructions and biostratigraphy. The database, described here, will facilitate the investigation of modern ostracode biogeography, regional community structure, and ecology. These data, when compared to downcore faunal data from sediment cores, will provide a better understanding of how the Arctic has been affected by climatic and oceanographic change during the Quaternary. Images of all species and biogeographic distribution maps for selected species are presented, with brief discussion of representative species’ biogeographic and ecological significance. Publication of AOD-2015 is open-sourced and will be available online at several public websites with latitude, longitude, water depth, and bottom water temperature for most samples. It includes material from Arctic abyssal plains and submarine ridges, continental slopes, and shelves of the Kara, Laptev, East Siberian, Chukchi, Beaufort Seas, and several subarctic regions.     

云南鹤庆晚第四纪介形类生态特征初探

云南鹤庆盆地晚第四纪钻孔剖面分析出介形类13属,32种,多为地方性属种,根据介形类丰度,分异度,百分含量及组合分子在剖面中的分布情况,结合剖面同步分析的总有机碳含量（TOC）,碳-氮比（C/N）,碳酸盐含量,孢粉等数据,并利用已有相关的介形类生态资料,对介形类生态特征进行初步探讨。研究结果表明：温度,矿化度,水流动态,水循环状况,pH值,深度,湖泊流域生产力等环境因素对介形类组合面貌,定量数据,壳饰等特征均有一定影响,其中,介形类丰度,分异度与温度,矿化度关系最为密切。     

The Fine Structure of a Sensory Organ of a Cladocop Ostracode (Crustacea) Belonging to the Organ of Bellonci (Sensory Pore) Complex

Andersson, A. 1980. The fine structure of a sensory organ of a cladocop ostracode (Crustacea) belonging to the organ of Bellonci (sensory pore) complex. (Department of Zoology, University of Lund, Sweden.) — Acta zool. (Stockh.) 61(1): 51–58. The organ of Bellonci, a complex of cephalic receptors, has previously been reported from two ostracode groups. On morphologic grounds, a cephalic receptor of a third ostracode group (Cladocopa) is believed to be an organ of Bellonci. The organ is situated on the forehead above the first pair of antennae and consists of two feathered hairs. Two nerves, each formed by one dendrite, run from the protocerebrum into the hairs where they terminate with ramose cilia. The dendrites, as well as the cilia and ciliary branches, are enveloped by glial cells. Distally, these cells form cavities around the ciliary branches. The ciliated neuronal connection and the glial cavities, together with other morphologic characteristics of the organ, support a homologization with the organ of Bellonci of other myodocopid ostracodes.     

Ostracodes du Cénomanien supérieur et du Turonien de la zone sous-pyrénéenne orientale (Corbières méridionales, SE France). Systématique, biostratigraphie, paléoécologie et paléobiogéographie

Thirty-four species of ostracodes are collected in the platform series of the Southern Corbières; two biostratigraphical assemblages, with 13 and 29 species, are respectively recognized in Cenomanian and Upper Turonian; palaeoecology is specified. At that time, the ostracode sub-province of South-West France, established on Southern Corbières, Aquitaine, Touraine-Poitou-Charentes region and Provence, is connected with Eastern and Northern regions and countries: Sub-alpines ranges, Paris Basin, Great Britain, Switzerland and Bohemia, and with the Iberian Peninsula, sub-province of North-Central Spain and Western Portuguese Basin. The crossing of the Tethys and the Atlantic Ocean is realized, in Turonian, by some rare species.     

Distribution et caractéristiques des associations d’ostracodes au Pléistocène supérieur et Holocène au niveau de la marge orientale du détroit de Gibraltar (mer d’Alboran, Maroc)

A detailed study of the upper Pleistocene and Holocene ostracode fauna from the Moroccan margin of the Western Mediterranean is here presented based on sediments of three cores drilled near the Straits of Gibraltar (Sea of Alboran), between 300 and 550 m of depth. Information on the quantitative and qualitative distribution of the ostracodes was obtained, for the first time, in this area. This study also allowed to identify recall the main climatic and eustatic variations as recorded in the sediments and the faunal composition and to identify the corresponding chronological limits from the last glacial maximum to the present time.     

Ostracodes swallowed by Palaeozoic corals?

Middle Devonian heliolitids and favositids from Central Bohemia, belonging to Heliolites 'intermedius' LeMaitre and Favosites goldfussi Orbigny , incorporated ostracode shells within their living corallite structures. The ostracode shells were sealed in by skeletal tissue that was septal in origin (Heliolites) or they were roofed over by tabulae (Favosites). The foreign shell was near the axis of the polyp when trapped within the coral skeleton. Only ostracodes, not other rounded shells or sedimentary particles, were trapped in this way. Approximately one in 30 favositid corallites and one in 70 heliolitid corallites display this peculiar condition, where the ostracode shells seem to have been swallowed by the polyps. A probable scenario involves the injury of the mouth area and the trapping of the ostracodes. A high probability that the basal part of the polyp experienced a controlled penetration is the most striking part of the process. □ Favositids, heliolitids, ostracodes, coral growth violence, behavior, Middle Devonian, Bohemia.     

Spatial heterogeneity of the population age structure of the ostracode Limnocythere inopinata in Hulun Lake, Inner Mongolia and its implications

Most existing studies of lacustrine ostracodes have been focused on species composition, and little attention has been paid to population structure. In this study, 39 surface-sediment samples from Hulun Lake, Inner Mongolia, were analyzed for ostracode species composition and 17 of them also for population structure of Limnocythere inopinata, which is the dominant ostracode in the lake. A total of nine ostracode species were recovered, most of which show high abundances at sites with rich plant detritus, implying the possible control of food supply on ostracode species occurrence in the lake. On the other hand, both the subfossil and the living populations of L. inopinata have greater numbers of early instars in deeper waters, while middle and late instars occur mostly in shallower waters, which is related to the grainsize composition of the substrate, denoting a hydraulic control on population structure. Pre- and post-mortem transport of ostracodes may be responsible for the observed within-lake changes in the population structure, although other factors such as migration, intrinsic population dynamics, and life cycle could also be involved. Our data provide insights into the interpretation of lake conditions when using ostracodes in paleolimnological research of lakes with similar natural settings.     

New data on late Santonian and early Maastrichtian ostracodes of the Saratov Region

The article presents a paleoenvironmental analysis of ostracode assemblages from Mezino-Lapshinovka (Upper Santonian) and Lokh (Lower Maastrichtian) Formations of the Vishnevoe section (Saratov Region). Two new species Cytherelloidea vishneviensis sp. nov. and Mauritsina mandelstami sp. nov. are described.     

Late Cretaceous biostratigraphy and paleoenvironmental reconstruction based on non-marine ostracodes from well SK1 (south), Songliao Basin,northeast China

High-resolution biostratigraphy has been established on the basis of fossil ostracodes from cores of the Cretaceous Continental Scientific Drilling borehole-Songke 1 (south) (SK1(s)) in the Songliao Basin, northeast China. More than 80 species belonging to 13 genera have been identified and 15 ostracode assemblage zones have been recognized. On the basis of ostracode paleoecological analysis, paleoenvironments, for example lake levels and salinity, have been reconstructed. Two inferred deep-water phases occurred during the deposition of the lower Qingshankou and lower Nenjiang formations, whereas shallower water phases probably occurred during deposition of the upper Quantou and uppermost Qingshankou to Yaojia formations. The salinity of paleo-Songliao lake is interpreted as predominantly freshwater to oligohaline. Oligohaline to mesohaline water environments may have occurred during the first and middle third members of the Qingshankou formation and the lower first and lower second members of the Nenjiang formation.     

Modern distribution of ostracodes and other limnological indicators in southern Lake Malawi: implications for paleocological studies

This modern distribution study from the southwest arm of Lake Malawi quantitatively relates variables of the lake environment to surficial assemblages of ostracodes and other paleoenvironmental indicators (molluscs, Botryococcus, fish, and charcoal) from 102 sites, across a gradient of littoral to shallow profundal conditions. The goal of this research is to use the resultant relationships to help quantify paleoecological interpretations of the fossil record from sediment cores. Site locations varied by depth (1–60 m) and adjacent shoreline environment. Thirty-three ostracode species are identified from 54 sites including four new, undescribed species of Cypridopsinae (2) and Limnocythere (2). Ostracodes are extremely abundant between 1 and 25 m water depth, but are rare to absent between 30 and 60 m. This disappearance is probably taphonomically controlled, with carbonate dissolution in the death assemblage since abundant live ostracodes have been found in the lake at greater than 30 m depth, where bottom sediments lack calcium carbonate. Constrained correspondence analysis (CCA) of ostracode species abundance suggests depth and dissolved oxygen (DO) content to be the primary environmental variables affecting their distribution. Additional CCA models using all biological indicators suggest limnologic variables correlated with depth (e.g., bottom water temperature and DO) and adjacent shoreline environment were most significant.     

La diversité floristique de la végétation psammophile de la région de Tlemcen (nord–ouest Algérie)

This study is devoted to the analysis of the psammophyte of the coastal and semi-continental dunes in Tlemcen. Interesting results have been obtained, in particular, on the biological and ecological aspects of the psammophyte. The interpretation from Factoriel analysis of correspondences enabled us to identify the different phytosociological classes (Cakiletea maritimae, Ammophiletea, Quercetea ilicis, Therobrachypodietea and Stellarietea mediae). Some of these classes (Cakiletea maritimae and Ammophiletea) inhabit, exceedingly well, the embryonic dunes. Some species (Therobrachypodietea) colonize the quickset dunes. Lastly, some others (Quercetea ilicis) settle in the more mature and stable dunes. By using the phytosociological and phytodynamical data, we have been able to understand the vegetation and its diversity. To cite this article: H. Stambouli-Meziane et al., C. R. Biologies 332 (2009).     

L'etude des tests d'Ostracodes au microscope electroniquea balayage: Remarques et mise au point d'une technique de preparation

Examination under the scanning electron microscope of paleozoic ostracode tests is limited by the conservationof the shells. When the fossilized specimens are stuck on the top of a delicate wire with a varnish, they are observable from various sides without changing the preparation.