Cyclocypris Ovum Research Articles

Ostracods and the middle Miocene evolution of the Bugojno Basin (Bosnia and Herzegovina)

In the present study, the taxonomical and palaeoecological interpretations of non-marine ostracod assemblages from the Gracanica opencast coal mine are summarised. The results revealed three different ostracod assemblages within a 40-m succession. The oldest ostracod assemblage from the lower part of the section consisted primarily of pioneer species Fabaeformiscandona cf. pokornyi, Vestalenula cylindrica, Paralimnocythere rostrata, Cyclocypris ovum and Mediocypris cf. candonaeformis. Determined ostracods indicated a very shallow environment, with a low water energy. The second ostracod assemblage with the dominant species Cypridopsis cf. biplanata in the middle part of the succession corresponded to a shallow littoral environment, rich in vegetation with gradual water deepening. The third ostracod assemblage occurred in the upper part of the Gracanica section. Generally, marly sediments of the upper part of the succession contained abundant, thin, transparent and very poorly preserved ostracod valves that belonged to Candonidae gen. et sp. indet. taxon typical for a lake environment.

Piacenzian–Gelasian non‐marine ostracods from the Dunarobba Fossil Forest (Tiberino Basin, Umbria, central Italy)

AbstractThe taxonomy of some non‐marine ostracod assemblages from the Dunarobba Fossil Forest area (south Tiberino Basin, Umbria, Italy) is discussed, adding to the scientific understanding of Piacenzian–Gelasian non‐marine ostracods in central Italy and providing a palaeoenvironmental reconstruction of the shallow coastal lacustrine environments of the Palaeolake Tiberino. The ostracod assemblages include Darwinula stevensoni, Vestalenula cylindrica, Candona (Candona) improvisa, Candona (Neglecandona) neglecta, Candona (Neglecandona) angulata, Candona (Neglecandona) paludinica, Caspiocypris basilicii, Caspiocypris tiberina, Candonopsis kingsleii, Cyclocypris ovum, Ilyocypris bradyi, Ilyocypris decipiens, Cypris mandelstami, Zonocypris membranae quadricella, Potamocypris fulva, Cyprideis crotonensis, Cyprideis rectangularis and two new species: Hemicypris lomastroi sp. nov. and Paralimnocythere turgida sp. nov. In addition to widespread European species, the ostracod assemblages contain some rare species that were previously known from the Pliocene Paludinian Beds of Serbia. A cluster analysis applied to the ostracod frequency matrix has lead to the identification of four separate assemblages that can be attributed to several ecological niches, including emerged hydrosols, ephemeral coastal pools and a littoral lacustrine margin, which suggest a complex coastal environment.

Early Pleistocene (Calabrian) Ostracoda assemblage and paleoenvironmental characteristics of the Fevzipasa Formation,Western Anatolia

The study area is located about 40km west ofAydin city in western Turkey and includesNeogene to Quaternary sediments of the Fevzipasa Formation, which unconformably overlies the Miocene rock units. The Fevzipasa Formation is composed of conglomerates, sandstones, mudstones, marls, limestones and tuff layers and is unconformably overlain by recent deposits of the Söke-Milet Basin. The lower part of the Fevzipasa Formation is represented by coarse clastics and lacustrine carbonates followed by fine to coarse-grained sandstones bearing mollusc shells. Prominent tuff layers (lower and upper tuff layers) of this dominantly sandstone succession were radiometrically dated between roughly 2 and 1Ma. Based on small mammal fauna the age of the upper part of the formation is Early to Late Pleistocene. To investigate the paleoenvironmental evolution of the succession, forty-two samples were collected along two stratigraphic sections. Ostracoda assemblages together with Chara flora, Gastropoda and Pelecypoda and fish remains were recovered from only twenty-nine samples. Ostracoda assemblages include Candona neglecta, Cyclocypris ovum, Ilyocypris gibba, I. bradyi, Heterocypris salina and Scottia cf. S. pseudobrowniana. Additionally, fish remains belonging to the Cyprinidae family (Tinca sp., Leuciscus sp. and Leuciscus etilius) and Characeae gyrogonites referable to Nitellopsis obtusa, Chara sp., C. aspera, C. globularis, C. hispida, C. vulgaris, Lychnothamnus sp. and Sphaerochara sp. occurred in the samples. The ostracod, fish, and gyrogonite records all indicate that the Fevzipasa Formation was deposited in a paleoenvironmental setting characterized by permanent and shallow water bodies. According to the identified Ostracoda assemblages and combining all available stratigraphic data, the age of middle part of the Fevzipasa Formation is suggested as Early Pleistocene (Calabrian).

The non-marine Ostracoda of Lapland: changes over the past century

Novel faunistic data are presented from the poorly explored area of northern Lapland and comparisons are made between the present day ostracod diversity and historical records from a century ago. Twenty sites were sampled across Norwegian, Swedish and Finnish Lapland: eight to the west of the Scandinavian Mountain range, where the climate is milder under the influence of the Gulfstream, and 12 sites in the slope area east of these mountains, where the impact of the continental climate is stronger. The sample sites were mainly peat bogs fed by springs (the dominant habitat type in the study area), but also included helocrene springs, ditches, ponds and the littoral zone of lakes. In total 4376 individuals belonging to 16 species were collected. The most widespread and abundant species were Cyclocypris ovum, Candona candida and Pseudocandona rostrata, whereas Cyclocypris serena, Cryptocandona vavrai and Eucypris pigra were least abundant. The diversity of the ostracod assemblages to the west and to the east of the Scandinavian Mountains was significantly different, as measured by the Shannon diversity index. Mean values were 0.36 (western slopes) and 0.84 (eastern slopes). Three assemblage types were distinguished using UPGMA cluster analysis, with C. ovum, C. candida and P. rostrata as the three characteristic species. However, no statistically significant differences were revealed between the ostracod site assemblages when grouped geographically into west and east of the Scandinavian Mountains. Our results did not show any significant correlation between the Bray-Curtis similarity of the ostracod assemblages and the geographical separation between sites. The most marked difference in ostracod diversity between the present data and the records from the beginning of the 20th century seems to be a retreat of some Arctic species from the Lapland area and a shift of a few eurytopic species further to the north of Lapland. Possible factors influencing this shift are discussed.

The non-marine Ostracoda of Lapland: changes over the past century

Novel faunistic data are presented from the poorly explored area of northern Lapland and comparisons are made between the present day ostracod diversity and historical records from a century ago. Twenty sites were sampled across Norwegian, Swedish and Finnish Lapland: eight to the west of the Scandinavian Mountain range, where the climate is milder under the influence of the Gulfstream, and 12 sites in the slope area east of these mountains, where the impact of the continental climate is stronger. The sample sites were mainly peat bogs fed by springs (the dominant habitat type in the study area), but also included helocrene springs, ditches, ponds and the littoral zone of lakes. In total 4376 individuals belonging to 16 species were collected. The most widespread and abundant species were Cyclocypris ovum, Candona candida and Pseudocandona rostrata, whereas Cyclocypris serena, Cryptocandona vavrai and Eucypris pigra were least abundant. The diversity of the ostracod assemblages to the west and to the east of the Scandinavian Mountains was significantly different, as measured by the Shannon diversity index. Mean values were 0.36 (western slopes) and 0.84 (eastern slopes). Three assemblage types were distinguished using UPGMA cluster analysis, with C. ovum, C. candida and P. rostrata as the three characteristic species. However, no statistically significant differences were revealed between the ostracod site assemblages when grouped geographically into west and east of the Scandinavian Mountains. Our results did not show any significant correlation between the Bray-Curtis similarity of the ostracod assemblages and the geographical separation between sites. The most marked difference in ostracod diversity between the present data and the records from the beginning of the 20th century seems to be a retreat of some Arctic species from the Lapland area and a shift of a few eurytopic species further to the north of Lapland. Possible factors influencing this shift are discussed.

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

AbstractThe 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)

New and little-known ostracode species from the Middle Neopleistocene to Holocene of the southeastern West Siberian Plain

New data are provided on the ostracode fauna of the Middle Neopleistocene to Holocene of the southeastern West Siberian Plain. Several species are recorded for the first time in the West Siberian Plain: Fabaeformiscandona aff. hyalina (Brady et Robertson), F. harmsworthi Scott, F. holzkampfi Hartwig, Pseudocandona insculpta Muller, Candona weltneri Hartwig, C. inaequivalvis Sars, and C. muelleri jacutica Pietrzeniuk. New evidence is presented on the distribution of the species Pseudocandona stagnalis Sars, Eucypris pigra (Fischer), Dolerocypris fasciata Fischer, Cyclocypris ovum Muller, and C. triangula Negadaev. New species, Candona kazminae sp. nov. and Ilyocypris pustulata sp. nov., are described. The study resulted in establishing the Late Karginian ostracode association.

Ostracoda (Crustacea) association and a new species (Dolerocypris anatolia nov. sp.) from the Pliocene-Pleistocene Afşin-Elbistan (Kahraman Maraş) Coal Basin of Turkey

Ostracoda (Crustacea) association and a new species (Dolerocypris anatolianov. sp.) from the Pliocene-Pleistocene Afşin-Elbistan (Kahraman Maraş) Coal Basin of TurkeyThe Afşin-Elbistan Coal Basin, which is one of the largest and most important Pliocene-Pleistocene lignite basins of Turkey, is located in Eastern Anatolia. The basin was formed between two normal faults having NE-SW direction and these faults controlled both the sedimentation and the subsidence. The coal horizon of over 50 meters in thickness indicates the balance between the sedimentation and subsidence rates, and was preserved during peat deposition. Coals were generated in this extensive and shallow freshwater lake and evolved from the Pliocene to Pleistocene. Typical faunal and floral assemblages of this ancient Afşin-Elbistan freshwater lake are Ostracoda, Mollusca (Gastropoda and Pelecypoda), spore-pollen and Characeae (gyrogonites). Eleven Cypridoidea species were identified from the investigation area. Eight of them are already known (Candona neglectaSars,Candona iliensisMandelstam,Candonaaff.candida(Müller),Pseudocandona compressa(Koch),Cyclocypris ovum(Jurine),Ilyocypris gibba(Ramdohr),Cypris puberaMüller,Heterocypris salina(Brady)), whereas three belong to open nomenclature —Candonasp. andEucyprissp.;Dolerocypris anatolianov. sp. is proposed as a new species.DolerocyprisKaufmann is one of the largest genera among the freshwater Ostracoda. It has a very wide geographical distribution. Representatives of this genus are actively swimming species found in shallow zones of freshwater lakes and reported from small grassy water bodies with megascopic plants.Dolerocypris anatolianov. sp. is recorded from core samples of the Pliocene-Pleistocene Afşin-Elbistan Coal Basin for the first time.

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.

Freshwater Ostracoda (Crustacea) of Inari Lapland in northern Finland

Collections of ostracods from various habitats in and around Lake Inari, Finnish Lapland, provide the first record of these crustaceans from Finland north of the Arctic Circle. From a total of 35 sites visited, 14 species were collected, out of which four appeared to be new to Finland: Fabaeformiscandona lapponica , Pseudocandona pratensis , Eucypris pigra and Paralimnocythere relicta . Two major assemblage groups were recognised by clustering classification and multi-dimensional scaling ordination, one dominated by Cyclocypris ovum , the second by Candona candida . Taxonomic diversity of the most assemblages was of expected range based on the inventory of 53 freshwater species of Finland.

Holocene to Recent Ostracoda of Lake Sevan, Armenia: biodiversity and ecological controls

The morphology and dynamics of Lake Sevan, Armenia, have abruptly changed on several occasions during the Holocene. Arguably the most significant events took place about 4000 years BP, when a phase of aridity greatly reduced the size of the lake and about 2100BP when the combined effect of an episode of volcanic activity that dammed the single outlet to the basin and the initiation of a wetter climatic phase, culminated in the development of the modern lake. Archaeological evidence indicates the extent of the first event, while the development of aquatic communities and increase in diversity of, for example, ostracods, characterises the second. Recent environmental stress, caused by a significant drop in water level due to human activity has resulted in changes in the ecosystem and food chain, resulting in a decline in ostracod diversity compared to both the earlier Holocene and sub-Recent. The living fauna is characterised by abundant Candona neglecta and Cyprideis torosa, common sexually reproducing Limnocythere inopinata, and less common Fabaeformiscandona caucasica, Candona candida, Cyclocypris ovum, Cypria ophthalmica and Darwinula stevensoni.

Distribution and ecology of non-marine ostracods (Crustacea, Ostracoda) from Friuli Venezia Giulia (NE Italy)

From August 1981 to July 2007, 200 inland water bodies were sampled to gather information on the Recent ostracod fauna of Friuli Venezia Giulia (NE Italy). A total of 320 samples were collected from surface, interstitial and ground waters. Whenever possible, ostracod identification was performed at species level based on the morphology of both valves and limbs. Seventy-four taxa in 30 genera belonging to 9 different families (Darwinulidae, Candonidae, Ilyocyprididae, Notodromadidae, Cyprididae, Limnocytheridae, Cytheridae, Leptocytheridae and Xestoleberididae) were identified. The maximum number of taxa per site was seven. The most common species was Cypria ophthalmica (133 records), followed by Cyclocypris ovum (86 records), C. laevis (49 records), Cypridopsis vidua (40 records) and Notodromas persica (28 records). Of particular relevance is the occurrence of six species new to Italy: Microdarwinula zimmeri, Penthesilenula brasiliensis, Fabaeformiscandona wegelini, Pseudocandona semicognita, Candonopsis scourfieldi, and C. mediosetosa. Scanning electron microscopy images of valves are provided for most of the described taxa. Geographical distribution of ostracods and their occurrence in relation to environmental variables were examined. The results of this study indicate that Friuli Venezia Giulia hosts a very diverse ostracod fauna, representing a significant proportion of all ostracod taxa known thus far from Italy.

Limnological characteristics and recent ostracods (Crustacea, Ostracoda) of freshwater wetlands in the Parco Oglio Sud (Northern Italy)

We report the results of a study carried out in 2002 on the main limnological characteristics and on the ostracod communities of 16 wetlands of the Parco Oglio Sud (Northern Italy). Physical and hydrochemical variables were measured and ostracod samples were collected in different seasons (April, June, August, and October). Most of the considered sites were characterised by high concentrations of nitrogenous compounds due to washing out from cultivated areas, intermittent river flooding and internal recycling. Observed differences in macrophyte communities were consistent with trophic status of waters, with pleustonic forms dominating most degraded areas. Both morphology of valves (by scanning electron microscopy) and anatomy of soft parts were analysed for ostracod species identification. Nineteen ostracod species in five families were found. Two species, Candona weltneri and Pseudocandona compressa, are new records for Italy. Cypria ophthalmica was collected from all sampling sites; other relatively common species were Cypridopsis vidua, Cyclocypris ovum, and Candona weltneri. No clear seasonality was observed in community structure; highest species diversity occurred in June in most of the studied wetlands. The maximum number of species per site was seven, and a maximum of six species was found in a single sample. Ostracod occurrence in relation to environmental factors was examined using Canonical correspondence analysis (CCA). Total alkalinity and pH were the most important variables structuring the species assemblages. The ostracod fauna found in this area was compared to the known distribution of recent non-marine ostracods in Italy, and the validity of published checklists is discussed.

Sub-Recent Ostracoda from Qilian Mountains (NW China) and their ecological significance

23 ostracod species have been recorded from surface and short core samples from the Qilian Mountains, NW China. Brooks and rivers, small shallow meadow and oxbow pools and a lake were sampled at an altitude ranging from 2900 m to 3570 m asl. Brooks were dominated by Candona rawsoni, Ilyocypris cf. bradyi and/or Ilyocypris lacustris and Limnocythere inopinata. In river habitats Candona candida and Eucypris sp. were most abundant. Meadow pools with peaty, dystrophic waters mainly contained valves of Ilyocypris cf. bradyi and/or Ilyocypris lacustris and Eucypris sp. whereas the latter was replaced by Heterocypris incongruens in a shallow oxbow pool. Candona rawsoni, Cyclocypris ovum and Ilyocypris echinata were the most frequent species in the freshwater Lake Luanhaizi. The recorded taxa are mainly distributed in the holarctic realm but Fabaeformiscandona danielopoli and Ilyocypris echinata appear to be restricted to the cold mountainous region in China.

Ecology of Freshwater Ostracoda (Crustacea) from Lakes and Reservoirs in Bolu, Turkey

ABSTRACT Freshwater ostracods are important for interpreting the water quality of aquatic habitats. However, using ostracods in this way requires knowledge of their ecology and habitat preferences, particularly because species may show different responses to different ecological conditions. I documented ecological requirements of five ostracod species and their distribution in ten similar-sized lakes and reservoirs in Bolu, Turkey. Five species (Darwinula stevensoni, Cypria ophthalmica, Cypridopsis vidua, Cyclocypris ovum, Fabaeformiscandona fabaeformis) were found from natural lakes, while no ostracods were encountered from reservoirs. A canonical correspondence analysis suggested that salinity, temperature, redox potential, and pH were the four most influential factors on the species habitat preference in these lakes. These results were also supported with unweighted pair group mean averages (UPGMA) that also showed ostracod preference for certain ecological conditions in these lakes was mostly species-specific, depending on the changes in the levels of variables. UPGMA analysis for clustering of species and environmental data revealed three main species assemblages. The first group was represented by a single species, F. fabaeformis, whose occurrence was closely related to water hardness. The second group included two species, D. stevensoni and C. ophthalmica, that were found in relatively alkaline waters with moderate temperature. The third group was represented by two species, C. vidua and C. ovum.

The zooplankton crustacean of the temporary waterbodies of the Oasis of Palo (Rome, central Italy)

The WWF Oasis of Palo, 38 kms north of Rome, is one of the last remnants of the Mediterranean plain forest formerly covering the coastal areas of Latium. Within this preserved area, nine temporary waterbodies were periodically visited during 2001 to obtain information on their morphology, water cycle and faunal composition. In total, 25 crustacean species were listed and monthly changes in their abundance were recorded. Cladoceran species prevailed in all waterbodies (11 species, 7 genera, 2 families). Copepoda were represented by 8 species, 7 genera, 2 families. Ostracoda included 5 species, 5 genera, 3 families. Anostracans were recorded in only two pools and were represented by Chirocephalus diaphanus Prevost, 1803, the most common species in Italy. Chirocephalus kerkyrensis Pesta, 1936 usually occurring in the waterbodies of the Mediterranean maquis, was missing. Species richness was maximal in late autumn and winter, and correlated positively with pond duration, flooded area, water level and number of rainpools. The species most frequently recorded were Chydorus sphaericus O.F. Muller, 1785 and Daphnia curvirostris Eylmann, 1887 for Cladocera, Megacyclops viridis Jurine, 1820, Diacyclops bicuspidatus odessanus Shmankevitch, 1875 and Mixodiaptomus kupelwieseri Brehm, 1907 for Copepoda, Cyclocypris ovum Jurine, 1820 and Eucypris virens Jurine, 1820 for Ostracoda. Others, like Alona affinis Leydig, 1860, Ceriodaphnia pulchella Sars, 1862 (Cladocera), Macrocyclops albidus Jurine, 1820 (Copepoda), Herpetocypris reptans Baird, 1835 Fabaeformiscandona fabaeformis Fischer, 1854 (Ostracoda) were found in only one pool.

The life history of Cyclocypris ovum (Ostracoda) in a permanent karstic lake

We studied the life history of Cyclocypris ovum, a small candonid ostracod, in a Spanish mountain karstic lake (Lake La Cruz). Samples were collected from the littoral area of the lake between June 1996 and December 1998 and the relative abundances of all developmental instars were analysed. Hatching took place between November and May and juvenile development lasted around 6 months; adult life-span was 6-8 months. In summer, a sharp decline in adult population densities was observed, and juveniles completely disappeared until the next hatching period. This population decline is probably a result of mortality, and the commencement of dormancy in immature adults, which may move towards the bottom to enter dormancy buried in the sediments. These processes may be triggered by the combined effects of summer whiting and an increase in water temperature above 20°C. Densities of mature adults progressively increase in autumn, suggesting that the end of dormancy is stimulated by decreasing temperatures and turbulence. In this way, females lay eggs that will hatch mainly during the overturn period. In permanent waters, dormancy of an immature adult stage which optimises reproduction and growth under favourable conditions, could be more adaptive than resting egg production (as commonly occurs in ostracods inhabiting temporary waters). Further research is needed to know to what extent temperature variability and calcium carbonate precipitation affect the life history of this small, nektonic ostracod, which is common in northern Europe but rather rare at low altitudes in the Iberian Peninsula.

Ostracoda from springs on the eastern Iberian Peninsula: ecology, biogeography and palaeolimnological implications

An extensive survey was undertaken of 117 (mostly helocrene-type) springs on the eastern Iberian Peninsula to generate an ostracod database of use for palaeoecological studies. For this purpose, the main physico-chemical parameters of the habitat, including water chemistry, temperature, pH and oxygen content, were recorded. Twenty-eight species, with an average of two species per site, were recorded. Some of these are new records for the Iberian Peninsula ( Sarscypridopsis lanzarotensis and Paralimnocythere messanai). In addition, the presence in this area of several rare and little-known species is validated. Autoecological traits, deduced by means of Canonical Correspondence Analysis (CCA), have allowed the main habitat factors affecting the distribution of non-marine ostracods in this area to be determined. According to this analysis, four groups of springs, each one characterised by principal and secondary species, are distinguished: (1) Bicarbonate-rich springs with relatively low water temperature, low mineralisation and wet climate are characterised by Potamocypris zschokkei, Herpetocypris intermedia, and secondary species Ilyocypris bradyi, Ilyocypris inermis, Potamocypris villosa and Cyclocypris ovum. (2) Bicarbonate-rich springs with warm and oxygenated waters are characterised by Herpetocypris brevicaudata, S. lanzarotensis and Cypridopsis vidua as main species, and Notodromas persica, P. villosa and Cyclocypris ovum as secondary species. These latter two species are related to wetter climates and higher altitudes. (3) Bicarbonate-rich waters enriched with sulphate and/or chloride, also with warm water and often with high mineral content. Characteristic species are Paralimnocythere messanai, Ilyocypris gibba and Pseudocandona pratensis and secondary species Heterocypris incongruens, Heterocypris salina, Darwinula stevensoni, C. vidua, and Herpetocypris helenae (4) The last group is defined by brackish sulphate-rich and chlorinated waters with high temperature, and it is mainly composed of typical brackish species as Cyprideis torosa, Xestoleberis nitida or Loxoconcha elliptica. Secondary species are Sarscypridopsis cf. aculeata, Paralimnocythere psammophila, D. stevensoni and H. salina. The combination of biogeographical factors (i.e. latitude) and the relatively constant conditions of the springs (i.e. constant temperature) may explain the common occurrence of species which had previously been reported only in distant areas. S. lanzarotensis and P. messanai are examples of such species, their distributions were thought to be confined to the Canary Islands and the Italian Peninsula, respectively. Distinctive morphological carapace traits are provided for most species to facilitate the use of these ostracod species in the interpretation of past environments from sedimentary deposits.

Distribution and population dynamics of ostracodes (Crustacea, Ostracoda) in a karstic lake: Lake Banyoles (Catalonia, Spain)

Qualitative and quantitative benthic samples were collected monthly between December 1986 and December 1987 from several stations at various depths and basins in the karstic Lake Banyoles (Catalonia, Spain), to study the spatial distribution and seasonality of ostracodes. A total of eight ostracode species were found in the lake. Of these, Candona neglecta Sars, Isocypris beauchampi Paris and Cypria ophtalmica Jurine were the most common ostracodes at all depth stations. Darwinula stevensoni Brady & Robertson, Ilyocypris species (I. bradyi Sars and I. gibba (Ramdohr)), Cyprideis torosa (Jones) and Cyclocypris ovum Jurine, on the other hand, were confined to sublittoral and littoral areas of the lake.

Infestation of the Freshwater Ostracod Cypria aphthalmica (Jurine) by the Peritrich Nüchterleinella carneliae Matthes

Summary Brief details of the seasonal occurrence and levels of infestation by Nuchterleinella corneliae on its ostracod host are given. The species is also reported from the ostracod Cyclocypris ovum for the first time.