World subterranean ostracod biogeography: dispersal or vicariance

Origins of the present day distribution of several freshwater and marine phyletic groups of ostracods are described using both Recent and fossil data. Six examples of subterranean ostracods distributed world-wide are discussed. The first two examples (i.e. the Candoninae Namibcypridini and the Sphaeromicolinae) seemed, in a first approach, to fit well with the ‘vicariance model’ but a detailed study demonstrate that their present day distribution can not be seen as a consequence of any geological events. The four other examples (the Xestoleberis arcturi species group, the Tuberoloxoconcha, the Cavernocypris and Fabaeformiscandona wegelini) fit well with the ‘dispersionist model’. We propose a biogeographical model similar to the dispersal one which foccus on the ecological processes occurring at local and/or regional scales. Some present day species or their epigean ancestors may originally have been more widely dispersed. These species were predisposed to colonize subsurface habitats; a process that could occur polytopically and at various times. It is the degree of ecological flexibility, the width of ecological tolerance, the type of preadaptations, and the capacity to perceive and successfully invade new environments that allow subsurface ostracods to migrate actively or be dispersed passively through both subterranean and epigean aquatic systems and to settle in new places. But no centers of origin and direction of dispersal can be identified in our data. There is little known about the autecology of subterranean ostracod taxa with broad geographical ranges. Samples should be collected at fine (habitat) and broad scales (regional surveys) so that we can better understand the modes of ostracod dispersal across a range of spatial scales.     

First record of non-marine ostracods from the Paleogene “hamadian deposits” of Méridja area,west of Bechar (southwestern Algeria)

A new non-marine ostracod fauna from the Paleogene “hamadian deposits” outcropping west of Bechar (southwestern Algeria) has been recovered from lacustrine to fluvial deposits of the Oued Méridja section and fluvial deposits on the southern edge of the Hamada de Méridja section. Recently, these sections have been dated as late Thanetian – early Ypresian (latest Paleocene to earliest Eocene) and Ypresian – earliest Lutetian (early to earliest middle Eocene), respectively, based on charophytes. The associated ostracod fauna recovered consists of relatively mostly moderately to badly preserved specimens and comprises 14 taxa, none of which could be identified to species level in view of its poor state of preservation; we have nevertheless been able to identify and describe the following taxa: Herpetocypris sp., Cyprinotus? sp., Heterocypris? sp. 1 and sp. 2, Cypris? sp., Ilyocypris sp., Cytheroidea indet. sp. 1 and sp. 2, Limnocytheridae indet. sp. 1, Cypridoidea indet. sp. 1, Cyprididae indet. sp. 1, and Ostracoda indet. sp. 1, 2 and 3. Only Heterocypris sp. 1 occurs in both sections. Although the fauna can as yet not be related to the few other contemporaneous faunas reported from the wider palaeogeographic area, it adds important new information to our poor knowledge on Eocene non-marine ostracods in North Africa and southern Europe. The Méridja sections and area are promising regarding the discovery of more, better preserved material and further studies, and one main limitation to the correlation of the fauna is the hitherto insufficient taxonomic knowledge on many faunal elements of Eocene non-marine ostracods to which our section contributes considerably.     

Freshwater ostracod assemblages and their relationship to environmental variables in waters from northeast Germany

An ecological calibration dataset for freshwater ostracods from 33 localities throughout West-Pomerania (Mecklenburg-Vorpommern, Germany) was evaluated using multivariate statistical methods. A total of 47 freshwater ostracod species were identified. Nine species were rediscovered after 100 years since the last published record and Candonopsis scourfieldi and Pseudocandona sucki was recorded for the first time in the study area. Special emphasis is put on the phenology of each species to gain information on the water characteristics at the time of their last moult. Canonical correspondence analysis (CCA) revealed that the ecological variables such as water temperature, Ca, Mg, and lake area were statistically most significant (p < 0.005; n = 72) in explaining variation in the distribution of ostracod assemblages. In addition, a transfer function was developed for paleolimnological approaches, based on a weighted-averaging (WA) model to calculate water temperature from the relative abundances of 22 selected ostracod species. This model was successfully applied to infer lake water temperature from subfossil ostracod assemblages collected from lacustrine deposits in northeast Germany (Lake Krakower See). Electronic supplementary material Electronic supplementary material is available for this article at and accessible for authorised users.     

The ostracod fauna (Crustacea,Ostracoda) of the profundal benthos of Loch Ness

We report the results of quantitative and qualitative investigations of the ostracod fauna of the profundal benthos of Loch Ness, an oligotrophic lake in Scotland, UK. Six ostracod species were recorded from profundal samples: Candona angulata, C. candida, Cryptocandona reducta, Cypria ophthalmica, Cyclocypris ovum and Potamocypris smaragdina. In addition, Psychrodromus robertsoni was found in fish gut contents. The mean density of profundal ostracods was 262 individuals m², with an average Brillouin's Diversity of 0.7. A weak inverse relationship between fish body weight and the number of ostracods eaten is reported for Arctic charr, Salvelinus alpinus.     

An example of intralacustrine evolution at an early stage: the freshwater ostracods of the Miocene crater lake of Steinheim (Germany)

I present the findings of two detailed studies on Steinheim lake ostracods carried out over the last eight years. The 178 samples studied cover a combined section about 30 m thick, comprising the whole sequence of seven planorbid beds. Of the 53 species found, 44 occur in the basic sediment layers, the kleinibeds. In contrast, all of the subsequent beds contain 16 species, and only seven species withstood the extinction at the kleini–steinheimensis boundary.This may be mainly due to the loss of littoral habitats brought about by a constantly increasing lake level, as the majority of the species in the kleinibeds were shallow water dwellers. Long-term lake level fluctuations are considered the most important external factor of the post-kleini period. Density fluctuations of the ostracods Pseudocandona steinheimensis and Potamocypris gracilis broadly reflect these water level fluctuations. At the beginning of the sulcatusperiod, when the lake level was very high, some species show morphological changes in their carapaces. During this time Leucocythere immigrata split into the daughter species L. sieberi and L. esphigmena. In the following trochiformis period, when the water level was lowest, the most curious carapace sculptures appear. The morphological changes detected, however, cannot simply be interpreted as ecophenotypic. The speciation event in Leucocythere, the non-recolonization with ubiquitous species during the low water level stage (trochiformis period), as well as the types of morphological changes indicate mainly evolutionary processes, as also the planorbid molluscs prove. Moreover, ostracods and planorbids show convergent evolutionary patterns. Compared with data on ostracod speciation in ancient lakes, the ostracod assemblage of Lake Steinheim seems to be a good palaeontological example of intralacustrine evolution at an early stage.     

A new well-preserved ostracod fauna from the middle Burdigalian (lower Miocene) of the North Alpine Foreland Basin

The marine middle Burdigalian sediments of the North Alpine Foreland Basin (NAFB) or Molasse Basin are well known for abundant occurrences of benthic foraminifers and ostracods. However, taxonomic studies of ostracod assemblages are comparatively rare and, given its abundance, the group remains heavily understudied. Here we report a new, rich and well-preserved ostracod fauna from the middle Burdigalian Neuhofen Formation at Mitterdorf, in the northeastern part of the NAFB. The material comprises a total of 3029 ostracod specimens. We identified 44 species; all species are described and, with one exception, illustrated. Our material reveals the presence of 17 ostracod species that were previously unknown from the middle Burdigalian in the NAFB, i.e., Cytherella aff. vulgatella, Cytherella aff. méhesi, Bairdoppilata aff. subdeltoidea, Paranesidea? sp., Paracypris aff. aerodynamica, Parakrithe dactylomorpha, Pseudopsammocythere sp., Callistocythere daedalea, Costa aff. reticulata, Ruggieria aff. longecarenata, Heliocythere aff. vejhonensis, Heliocythere sp., Loxocorniculum hastatum, Neocytherideis cypria, Cytheretta cf. tenuipunctata dentata, Cytheropteron cf. ruggierii, and Semicytherura resecta. The palaeobiogeography of the ostracods indicates a relatively open marine Burdigalian connection between the NAFB and the Mediterranean Sea, in agreement with previous work. Our data also suggest that a significant degree of endemism existed in the middle Burdigalian sea of the NAFB, of which previous studies yielded only sparse signs. Moreover, our results indicate that some ostracod species survived the late Burdigalian sea retreat from the NAFB by dispersing eastward into the adjacent regions (Vienna Basin, Carpathian Foredeep), where marine conditions still prevailed. A compilation of all known middle Burdigalian ostracod faunas from the NAFB documents a high species diversity, with over 120 species. Their spatial distribution, with many species being restricted to a single site, suggests heterogenous microhabitats, possibly influenced by small-scale differences in water depth, nutrient availability and oxygenation.     

Middle Permian Ostracods from Tak Fa Limestone, Phetchabun Province, Central Thailand

This paper presents the first Permian ostracod fauna discovered in Thailand. The ostracods are recovered from the Tak Fa Limestone (Middle Permian) in Phetchabun province, central Thailand. The ostracods belong to eight genera and 15 species. Four species are newly described: Sargentina phetchabunensis nov. sp., Geffenina bungsamphanensis nov. sp., Reviya subsompongensis nov. sp. and Bairdia takfaensis nov. sp. The ostracod assemblages characterize a shallow marine, near shore environment at the time of deposition. Except for one species, which shows palaeobiogeographical links between Central Thailand and South China, all the other species are endemic.     

The species composition and distribution of ostracods (Crustacea,Ostracoda) in rockpools on islands in the Kandalaksha Bay of the White Sea

A total of 15 species of ostracods of 7 genera and 3 families of the suborder Podocopa Sars have been recorded in rockpools of the Kandalaksha Bay in the White Sea. Among them, Potamocypris pallida Alm is a new species for the fauna of Russia. Data on species composition and the dominant complex and ecological features of ostracods which inhabit waters of rockpools are presented.     

On the Cyprideis species flock (Crustacea, Ostracoda) in Lake Tanganyika, with the description of four new species

Four new species, belonging to three genera, of ostracods from Lake Tanganyika are described: Mesocyprideis nitida sp.nov., Romecytheridea belone sp.nov., R. plegma sp. nov. and Cyprideis loricata sp. nov. The Cyprideis species flock of Lake Tanganyika now consists of 17 formally described species (16 endemic) in 6 genera (4 endemic). The geographical and ecological distribution of the four species is briefly discussed and some supplementary remarks on the radiation of the Cyprideis species flock in Lake Tanganyika are offered.     

Distribution and taxonomy of shallow marine Ostracods from Northern Socotra Island (Indian Ocean) - Yemen

Forty-seven species belonging to 30 genera of ostracods have been identified from Recent shallow marine sediments collected along the northern coastline of the island of Socotra (Indian Ocean). The systematics and distribution of these ostracods are discussed. Three genera, Loxoconcha, Bosasella, and Xestoleberis are found to have high species diversity. The species Loxoconcha ghardaqensis, Moosella striata are best documented in the Red Sea and Gulf of Aden while Kotoracythere inconspicua and Triebelina sertata were found to be the most widespread species. The fauna shows a close affinity to other ostracod assemblages of the Indo-Pacific region, East African coast and Red Sea.     

太湖介形虫分布与水环境因子间关系的典范对应分析

2004年9月至2005年8月间对太湖介形虫分布状况进行了季节性的调查,共获得介形虫15种,其中克氏瘤丽星介Physocypria kraepelini,豆形豆形玻璃介(比较种)Fabaeformiscandona cf.fabaeformis和塔尔薄丽星介Dolerocypria taalensis的出现频度分别达71.05%、44.74%和42.11%,为太湖水体中的常见种。相似性分析(UPGMA)结果表明太湖介形虫可分为四个不同的类型,即终年出现物种、仅秋季出现物种、夏秋季出现物种和仅春季不出现的物种。应用典范对应分析(Canonical Correspondence Analysis,CCA)对太湖38个样点的15种介形虫与9个环境因子关系研究的结果是介形虫与环境因子间的相关性高达100%,提示太湖水体环境因子变化影响了介形虫的分布和季节性变化;水体的9个环境因子中的pH值、植被密度、总磷和总氮对介形虫的分布影响最大;而化学需氧量和溶氧量对其也有一定的影响。从物种分布状况看,稳定湖花介Limnocythere stationis对水体中环境因子的敏感性明显高于其它物种,其高分布频度对高总磷和高叶绿素具指示作用;太湖中的三种常见种介形虫(克氏瘤丽星介、豆形豆形玻璃介(比较种)和塔尔薄丽星介)的分布主要受总磷和化学需氧量的影响,其高分布频度是水体高化学需氧量的良好指标种;在高总氮和高化学需氧量的春季水体中无角尾狭星介Stenocyprisderupta,近球形金星介Cyprissubglobosa,上野湖湾介Strandesiauenoi,绿色湖湾介S.viridis,条纹湖湾介S.vittata,环星介(未定种)Zonocypris sp.和史氏达尔文介Darwinula stevensoni的出现,暗示这些物种的高分布频度可以指示水体中的低总氮和低化学需氧量。     

Land use and ostracod community structure

Ostracods are important members of the benthos and littoral communities of lake ecosystems. Ostracods respond to hydrochemistry (water chemistry) which is influenced by climatic factors such as water balance, temperature, and chemicals in rainfall runoff from the land. Thus, at local scales, environmental preferences of ostracods and characteristics of lakes are used to infer changes in climate, hydrology, and erosion of lake catchments. This study addresses potential drivers of ostracod community structure and biodiversity at multiple spatial scales using NMS, CART^?, and multiple regression models. We identified 23 ostracod species from 12 lake sites. Lake area, maximum depth, spring conductivity, chlorophyll a, pH, dissolved oxygen, sedimentary carbonate, and organic matter all influence ostracod community structure based on our NMS. Based on regression analysis, lake depth, chlorophyll a, and total dissolved solids best explained ostracod richness and abundance. Land uses are also important community structuring elements that varied with scale; locally and regionally agriculture, wetlands, and grasslands were important. Nationally, using regression tree analysis of lakes sites in the North American Non-marine ostracod database (NANODe), row-crop agriculture was the most important predictor of biodiversity. Low agriculture corresponded to low species richness but greater landscape heterogeneity produced sites of high ostracod richness.     

Combined effects of local environment and continental biogeography on the distribution of Ostracoda

Summary 1. The relationship between altitudinal gradients on small spatial scales and latitudinal gradients on broader scales has been repeatedly recognised in the biogeography of animals and plants. However, little is known about this topic in the ecology and biogeography of ostracod communities in Mediterranean flowing waters or the factors underlying these spatial patterns. 2. We analysed the ostracod assemblages of near‐natural headwater streams in the Betic and Pre‐Betic Mountains in the southern Iberian Peninsula to decipher the most important environmental gradients structuring ostracod communities on a local scale. In addition, the European altitudinal and latitudinal distributions of the most commonly found species were analysed with GIS and regression models to compare geographical effects from local to continental scales. 3. Forty sampling sites, distributed among six catchments and ranging in altitude between 150 and 1940 m a.s.l., were sampled seasonally. Limnological and geographical information was also recorded for each sample. Seventeen ostracod species were found, two of which were new findings for the Iberian Peninsula: Potamocypris fulva and Cypria reptans. The most common species were Potamocypris zschokkei, Candona neglecta, Herpetocypris brevicaudata, Cyclocypris ovum, Potamocypris villosa and Pseudocandona albicans. The distribution of these species in 918 European locations was analysed to test the hypothesised change in altitudinal distribution with varying latitude. 4. The best subset of logistic and linear regression models, selected by means of the information‐theoretic approach, found that oxygen content and the variables related with substratum and discharge were the most important variables with a negative influence on ostracod presence, abundance and species richness on a local scale. These findings suggest that the negative effect on benthic invertebrates of physical disturbances relates to high flow velocity and turbulences. 5. Multivariate ordination methods show how altitude and water chemistry are the most important variables to explain the distribution of ostracod assemblages on the small spatial scale. On a larger scale, differences in latitudinal distribution throughout Europe were significant for the six most common species found in Granada. In addition, four of these showed significant negative linear relationships between latitude and altitude in Europe, supporting the important effect of climate on local and continental scale distributions. While ostracod biogeographies are still poorly known, our results indicate the influence of Quaternary climate variability on ostracod dynamic colonisation and extinction in Europe in accordance with species‐specific temperature and water chemistry preferences.     

Sediment penetration depths of epi- and infaunal ostracods from Lake Geneva (Switzerland)

Many (palaeo-)environmental parameters can be deduced from ecological and chemical analyses of ostracods. However, the specific ecology of each taxon has a great impact on its reaction to changing environmental conditions. As a consequence, each taxon records these changes differently. The mean penetration depth (MPD) and relative individual abundances have been documented along sediment depth profiles for the dominant sub-littoral to profundal species of ostracods in western Lake Geneva, Switzerland, and this data can be used to estimate their preferential habitat in terms of sediment depths. Isocypris beauchampi, Limnocytherina sanctipatricii, Cypria ophtalmica forma lacustris at 13-m water depths, Limnocythere inopinata, and a winter generation of Herpetocypris reptans have the shallowest habitat preferences at the study sites (MPDs of 0.45, 0.48, 0.49, 0.60, and 0.81 cm, respectively). These results suggest that these populations may be regarded as being preferentially epifaunal forms. Populations of Cytherissa lacustris (MPDs of 0.61, 0.73, and 0.82 cm at 13-, 33-, and 70-m water depths, respectively), Cypria ophtalmica forma lacustris at 70 m (MPD = 0.96 cm), Fabaeformiscandona caudata (MPD = 0.99 cm), and a summer generation of Herpetocypris reptans (MPD = 1.03 cm) were identified as being infaunal. Candona neglecta is the species that was found the deepest in the sediment of Lake Geneva, with MPDs of 0.65, 1.22, and 1.30 cm at 13-, 33-, and 70-m water depths, respectively. Information on the sediment texture and oxygen concentrations inferred from the analyses of sediment pore water suggest that the oxygen content of the sediment pore water is not the only dominant parameter controlling the differences in ostracod sediment penetration depths observed among the different sites, but that they might also be influenced by the sediment ‘softness,’ which itself depends on grain size, water content, and the abundance of organic matter in sediment.     

On a new species of Fabaeformiscandona KRSTIC, 1972 (Crustacea, Ostracoda) from China, with a preliminary checklist of Recent Chinese non-marine ostracods

Fabaeformiscandona danielopoli n.sp. isdescribed from the Chinese Lake Erhai, a freshwaterlagoon of the ancient saline lake Qinghai. The speciesbelongs to the acuminata-group of the genus andis characterized by the shape of both male and femalevalves and by the morphology of the female genitallobe and of lobe a in the hemipenis. The new speciesis quite rare in its type locality and might beendemic to the ancient Qinghai basin. A checklist ofRecent non-marine Chinese ostracods is offered inappendix.     

Diversity and paleoenvironmental significance of Middle Triassic ostracods (Crustacea) from northern Thailand: Pha Kan Formation (Anisian,Lampang Group)

The Pha Kan Formation that crops out at the Phra That Muang Kham section, south of Lampang city, was measured and sampled for ostracod analysis. We here report the occurrence of 29 species distributed among 14 genera. Four new species are described: Triassocypris phakanella Forel nov. sp., Leviella lampangensis Forel nov. sp., Bektasia yawella Forel nov. sp. and Hungarella poli Chitnarin nov. sp. The present data represent the first detailed report of Middle Triassic (Anisian) ostracods from the Sukhothai terrane and the first insight into diversity dynamics following the end-Permian extinction in this area. The ostracod assemblages of the Phra That Muang Kham section are discussed and document an important shift from siliciclastic to carbonate conditions, from a protected to an open marine environment, followed by a slight regressive trend up-section associated with repeated salinity fluctuations. This fauna illustrates the post-crisis recovery during the Middle Triassic and some hypothesis are issued on the distribution pathways of several taxa.     

Similar distribution pattern of different phenotypes of <Emphasis Type="Italic">Limnocythere inopinata</Emphasis> (Baird) in a brackish-water lake in Inner Mongolia

It has been recognized long ago that Limnocythere inopinata is a widely distributed ostracod and comprises various phenotypes. The taxonomy of the different phenotypes and their ecological differences, however, are still under debate. In this study, we investigated the relationships between ostracod distribution, water depth, and the substrate based on the analyses of species composition, abundance, and age structure of ostracods in 51 surface-sediment samples from Dali Lake in Inner Mongolia in order to reveal the distribution pattern and habitat characteristics of the ostracods. The identification of a total of 32,182 valves indicates that the dominant ostracod in Dali Lake is L. inopinata, which includes unnoded, 1-, 2- and 3-node and 1-carina phenotypes. The distribution of L. inopinata is affected both by the water depth and by the sand content of the substrate, and the phenotypes show their maximum abundances in the intermediate zone of the lake. All the phenotypes of L. inopinata display a similar preference for water depth and substrate, implying that the occurrence of different phenotypes is controlled by other factors. The age structure of L. inopinata is mainly related to the sand content, with the percentage of adults increasing and that of early juveniles decreasing with increasing sand content. Our data suggest that the occurrence of L. inopinata is closely related to water depth and substrate grain size, and different phenotypes of L. inopinata respond in a similar pattern to water depth and substrate.     

Distribution and community structure of Ostracoda (Crustacea) in shallow waterbodies of southern Kenya

The current study presents the ostracod communities recovered from 26 shallow waterbodies in southern Kenya, combined with an ecological assessment of habitat characteristics. A total of 37 waterbodies were sampled in 2001 and 2003, ranging from small ephemeral pools to large permanent lakes along broad gradients in altitude (700–2 800 m) and salinity (37–67 200 µS cm^?1). Between 0 and 12 species were recorded per site. Lack of ostracods was associated with either hypersaline waters, or the presence of fish in fresh waters. Three of the 32 recovered ostracod taxa, Physocypria sp., Sarscypridopsis cf. elizabethae and Oncocypris mulleri, combined a wide distribution with frequent local dominance. Canonical correspondence analysis on species–environment relationships indicated that littoral vegetation, altitude, surface water temperature and pH best explain the variation in ostracod communities. Presence of fish and water depth also influence species occurrence, with the larger species being more common in shallow waterbodies lacking fish. Based on Chao’s estimator of total regional species richness, this survey recovered about two-thirds (60–68%) of the regional ostracod species pool. Scanning electron micrographs (SEM) of the valve morphology of 14 ostracod taxa are provided, in order to facilitate their application in biodiversity and water-quality assessments and in palaeoenvironmental reconstruction.     

Ostracod Assemblages in Relation to Littoral Plant Communities of a Shallow Lake (Lake Świdwie,Poland)

The aims of this study included: specifying values of ecological parameters and Ostracoda species characteristic for different types of plant habitats occurring in lake systems, determining the impact of mud presence on the taxonomic structure and density of the ostracods, tracing seasonal changes in the structures of Ostracoda assemblages identifying the species typical of particular seasons. Various types of rushes and underwater meadows were taken into consideration as lake microhabitats. The research was conducted in the shallow Lake Œwidwie (NW Poland). Multivariate (constrained) ordination methods were used to analyse the relationships between species composition and environmental variables. In the lake and its margins 31 species of the Ostracoda were identified. The development of water vegetation during the vegetation season was conducive to growth in ostracod density. The accessibility of mud in plant habitats had a favourable effect on the general density of ostracods. Species which preferred a high mud content in their habitats included: Cypria ophtalmica, C. exsculpta and Physocypria kraepelini. Species typically encountered in underwater meadow habitats were: Cyclocypris ovum and Cypridopsis vidua. Underwater meadows of charophyte were characterized by the highest ostracod density in the whole lake system, with the average of 7860 ind. m^–2 and the maximum of 17 470 ind. m^–2. Species typically encountered in rush habitats included Notodromas monacha, Dolerocypris fasciata and Metacypris cordata. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)