Distribution of Recent ostracod species in the Lake Qinghai area in northwestern China and its ecological significance

In order to interpret the climate-change data using the ecological characteristics of the ostracods from the drill cores in Lake Qinghai, the distribution of Recent ostracods was studied in Lake Qinghai area. A total of 34 species belonging to the Ostracoda class of Crustacea were collected from different bodies of water in the Lake Qinghai area, and the ecological information for Recent ostracod species was studied. Among these 34 species, Cypris pubera, Eucypris dulcifons, Ilyocypris sp. 1, Ilyocypris sp. 2, Fabaeformiscandona caudata, Fabaeformiscandona hyalina, Herpetocypris reptans, Prionocypris gansenensis, Potamocypris villosa, Potamocypris smaragdina, Paralimnocythere compressa and Subulacypris sp. were first reported by us in the Lake Qinghai area. Some of the species identified exhibited cosmopolitan distributions, at least in the Holarctic region, but P. gansenensis and Ilyocypris echinata appeared to be restricted to the cold regions in northwestern China.The ecological significance of the primary ostracod species in the Lake Qinghai area was described according to the observations made during our time in the field and according to data from a number of reports. Our results indicate that the species diversity and abundance of ostracods may be related to water salinity in the Lake Qinghai area. The ecological information for ostracods can be used to distinguish different water environments and types based on the characteristics of one species or of an assemblage of several species.     

Body‐size distribution and biogeographical patterns in non‐marine ostracods (Crustacea: Ostracoda)

The idea that free‐living minute organisms have ubiquitous distributions has been recently revitalized, causing significant controversy. The ubiquitous model predicts that a threshold where ubiquity leaves room to biogeography might exist somewhere along the animal body‐size range. In the present study, such a prediction is tested by analysing body‐size frequency distribution, species distribution, and local‐to‐global species ratio at the scale of biogeographical realms in cypridoidean non‐marine ostracods, a group with a body‐size range in the ubiquity–biogeography (U‐B) boundary. Data were gathered for all described extant cypridoidean ostracod species (N = 1761), with body‐size recorded for 1134 of them. Although local‐to‐global species ratios show significant over‐dispersal of small‐body ostracods for the Palaearctic and the Australasian regions, there are explanations alternative to the ‘Everything is Everywhere’ model that can account for such a result. Indicators of taxonomic structure do not support the hypothesis of a random distribution of cypridoidean species among realms. Nevertheless, the strong biogeography signal occurring at a large scale vanishes at the local scale (country‐level within the Palaearctic), and suggests wide dispersion within biogeographical realms. Additional factors, including inconsistent taxonomic criteria for species recognition, uneven sampling effort, and an excess of ‘single‐report’ occurrences, have been identified too as potential distorters of the observed patterns. Taxonomic harmonization, open databases of biogeographical data, and better ecological information are suggested as critical goals that need to be achieved for further understanding of ostracod global distribution patterns. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109 , 409–423.     

Ostracods from the marginal coastal Lower Cretaceous (Aptian) of the Central Tunisian Atlas (North Africa): Paleoenvironment,biostratigraphy and paleobiogeography

This work provides the first detailed taxonomic study of ostracod species from the Lower Cretaceous (Aptian) marginal coastal deposits of the Central Tunisian Atlas, the Kebar Formation, as well as biostratigraphic, paleoecological and paleobiogeographic implications. The ostracod fauna provides new insights into the depositional environment and biostratigraphic framework of the Kebar Formation, and is represented mainly by freshwater and brackish-water species among them, Perissocytheridea tunisiatlasica nov. sp., is newly described. The environmental setting of this formation comprises marginal-littoral conditions in its lower part, thus not exclusively non-marine/continental as assumed previously. The ostracod associations from the studied locality, Jebel Ksaïra, indicate a minimum age of Early Aptian as recently attributed to the lower member of the Kebar Formation based on charophytes (presence of Late Barremian to Early Aptian Globator maillardii var. biutricularis Vicente and Martín-Closas, 2012), whereas an Early Albian age had been previously assigned to the Jebel Kebar site. The relative sea-level fall documented in the lower member of the Kebar formation at Jebel Ksaïra might correspond to the 3rd order cycle major eustatic sea-level fall event starting at the base of the Aptian. Paleobiogeographically, the non-marine ostracod fauna newly discovered in the Kebar Formation shows some affinities to contemporaneous faunas of southern and western Europe, e.g. that of the uppermost Weald Clay Group of southern England (Cypridea fasciata subzone of Horne, 1995), West Africa, and possibly to eastern South America (Brazil). Hence, the studied ostracods further support the hypothesis of supraregional faunal exchange by passive ostracod dispersal during the Early Cretaceous – between Europe and Northern Africa on the one hand, and eastern South America/western Africa and North Africa on the other hand. This leads to the hypothesis that the Peri-Tethyan islands could have worked as effective bridges for non-marine ostracods to become widely dispersed passively by “island-hopping” of larger animals and thus, ultimately, facilitated intercontinental faunal exchanges between South America and Europe – potentially even Asia – via North Africa during the Early Cretaceous.     

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.     

Locomotory,ventilatory and metabolic responses of the subterranean Stenasellus virei (Crustacea,Isopoda) to severe hypoxia and subsequent recovery

The locomotory and ventilatory activities and the intermediary and energy metabolism modifications of the hypogean aquatic isopod crustacean Stenasellus virei were investigated in severe hypoxia (Po₂ < 0.03 kPa) and subsequent recovery. The aims of this study were i) to determine why the subterranean species displayed a greater tolerance of hypoxia than numerous other epigean crustaceans, ii) to confirm previous results obtained with four hypogean and epigean crustaceans, iii) to compare the responses to severe hypoxia in hypogean amphipods and isopods, and iv) to better understand the ecological problems of the hypogean organisms survival in subterranean habitats. S. virei responded to experimental long-term, severe hypoxia with classical anaerobic metabolism mainly characterized by a decrease in adenosine triphosphate (ATP) and phosphagen, utilization of glycogen and glutamate, and accumulation of lactate and alanine. Lactate was also largely excreted by this organism, which is unusual for crustaceans in general. Compared to most other epigean crustaceans, the isopod S. virei showed high amounts of stored glycogen and arginine phosphate. These differences in glycogen and phosphagen stores, and the ability to reduce energetic expenditures linked to locomotion and ventilation, extended the survival of S. virei under experimental anaerobiosis. During recovery, the isopod S. virei showed a higher capacity for glyconeogenesis from lactate and a faster and total replenishment of ATP and arginine phosphate levels than epigean crustaceans. Data concerning responses to hypoxia and subsequent recovery in S. virei are similar to those previously obtained with two other hypogean amphipods, except that this isopod did not synthesize succinate in anaerobiosis.     

The Laterosensory Canal System in Epigean and Subterranean Ituglanis (Siluriformes: Trichomycteridae), With Comments About Troglomorphism and the Phylogeny of the Genus

The laterosensory system is a mechanosensory modality involved in many aspects of fish biology and behavior. Laterosensory perception may be crucial for individual survival, especially in habitats where other sensory modalities are generally useless, such as the permanently aphotic subterranean environment. In the present study, we describe the laterosensory canal system of epigean and subterranean species of the genus Ituglanis (Siluriformes: Trichomycteridae). With seven independent colonizations of the subterranean environment in a limited geographical range coupled with a high diversity of epigean forms, the genus is an excellent model for the study of morphological specialization to hypogean life. The comparison between epigean and subterranean species reveals a trend toward reduction of the laterosensory canal system in the subterranean species, coupled with higher intraspecific variability and asymmetry. This trend is mirrored in other subterranean fishes and in species living in different confined spaces, like the interstitial environment. Therefore, we propose that the reduction of the laterosensory canal system should be regarded as a troglomorphic (= cave‐related) character for subterranean fishes. We also comment about the patterns of the laterosensory canal system in trichomycterids and use the diversity of this system among species of Ituglanis to infer phylogenetic relationships within the genus. J. Morphol. 278:4–28, 2017. ©© 2016 Wiley Periodicals,Inc.     

An invaded invader: high prevalence of entocytherid ostracods on the red swamp crayfish <Emphasis Type="Italic">Procambarus clarkii</Emphasis> (Girard, 1852) in the Eastern Iberian Peninsula

The American red swamp crayfish Procambarus clarkii (Girard, 1852) was introduced in 1973 into the Iberian Peninsula for commercial purposes. As a result of both the expansion from the Iberian Peninsula and, probably, further introductions in other European countries, now it is widely distributed throughout much of Europe. The ecological impacts of this invading crayfish have received increasing attention, but nothing is known about its symbiotic entocytherid ostracods outside the American continent. The present survey has examined more than 200 crayfishes from 12 localities distributed over a wide area of Eastern Spain. Entocytherid ostracods were extracted from individual crayfishes and they were identified, counted, assigned to developmental instars and sexed. In all the study locations but one, we found at least one crayfish individual infected by entocytherid ostracods and the species determined was the same in all cases: Ankylocythere sinuosa (Rioja, 1942). The number of ostracods on individual P. clarkii varied notably in relation to crayfish size and also differed significantly among sampling sites. The crayfish size effects on ostracod densities might be related to the amount of resources and to the crayfish age and moulting frequency affecting ostracod distribution and population structure. In addition, the spatial variation in ostracod densities could also be related to site-specific habitat traits and the variability of crayfish population dynamics. Our study represents the first citation of an alien entocytherid species in Europe and demonstrates its wide distribution in the Iberian Peninsula. Further research is needed to know the potential effects of this ostracod species on the ecology of P. clarkii and of native species, with implications on the management of this aquatic invader.     

Invasive South American floating plants are a successful substrate for native Central African pleuston

Eichhornia crassipes, commonly known as water hyacinth, is a free-floating perennial aquatic plant native to South America, which has been widely introduced on different continents, including Africa. E. crassipes is abundant in both the Congo (Africa) and Amazon (South America) River catchments. We performed a comparative analysis of the ostracod communities (Crustacea, Ostracoda) in the E. crassipes pleuston in the Amazon (South America) and Congo (Africa) River catchments. We also compared the ostracod communities from the invasive E. crassipes with those associated with stands of the native African macrophyte Vossia cuspidata. We recorded 25 species of ostracods associated with E. crassipes in the Amazon and 40 in the Congo River catchments, distributed over 31 ostracod species in E. crassipes and 27 in V. cuspidata. No South American invasive ostracod species were found in the Congolese pleuston. Diversity and richness of Congolese ostracod communities was higher in the invasive (Eichhornia) than in a native plant (Vossia). The highest diversity and abundance of ostracod communities were recorded in the Congo River. The result of principal coordinates analysis, used to evaluate the (dis)similarity between different catchments, showed significant differences in species composition of the communities. However, a dispersion homogeneity test (PERMDISP) showed no significant differences in the variability of the composition of species of ostracods (beta diversity) within Congo and Amazon River catchments. It appears that local ostracod faunas have adapted to exploit the opportunities presented by the floating invasive Eichhornia, which did not act as “Noah’s Ark” by introducing South American ostracods in the Congo River.     

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.     

Geometric morphometrics throws light on evolution of the subterranean catfish Rhamdiopsis krugi (Teleostei: Siluriformes: Heptapteridae) in eastern Brazil

Rhamdiopsis krugi is a highly specialized troglobitic (exclusively subterranean) catfish from phreatic water bodies of caves located within two separated metasedimentary basins in the region of Chapada Diamantina, Bahia state, Brazil. In order to test the hypothesis of isolation with differentiation of the groups from the Una‐Utinga and Irecê metasedimentary basins, we compared five populations among themselves and with an epigean species of Rhamdiopsis. This was accomplished using geometric morphometrics, a powerful tool for detecting differences in body shape at population and species levels. All studied samples differed significantly from each other, the epigean sample being the most distinct and the Una Basin populations clustering together. Geological and hydrological barriers explain the differences among the subterranean populations. We discuss our results together with the autapomorphies found in R. krugi, which validate its monophyly. These results imply an old age for the R. krugi clade, more than 10 Myr; alternative hypotheses are also presented. We propose a two‐step vertical colonization model of the subterranean habitat through the hyporheic zone by an epigean ancestral, with a progressive acquisition of the autapomorphies characterizing R. krugi. For conservation purposes, the two differentiated sets of populations should be considered and referred to as R. krugi ‘Una morphotype’ and R. krugi ‘Irecê morphotype’. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 114 , 136–151.     

Dynamics of pleustonic ostracod populations in small ponds on the Island of Martín García (Río de la Plata,Argentina)

The biogeography and ecological preferences of Neotropical freshwater ostracods are poorly known, and more so the dynamics of populations and habitat selection of species living in pleustonic environments of temporary ponds. In the present survey we analyze the population changes of ostracods living in pleustonic environments of small freshwater bodies on Martín García Island (Río de la Plata, Argentina). Between June 2005 and June 2007, monthly samples of floating vegetation from eight different ponds on the island were collected, and limnological parameters were measured in situ. The results of multivariate logistic regression showed that the presence of ostracods was significantly related to high dissolved oxygen content and high water temperature. In addition, multivariate regression analysis indicated that, when ostracods were present, their total abundance was negatively related to floating vegetation dry weight. Four ostracod species were found: Strandesia bicuspis, Chlamydotheca incisa, Cypridopsis vidua, and Bradleytriebella trispinosa. The seasonal variation in abundances indicated that populations of the most common species, S. bicuspis and C. incisa, were denser during the summer and autumn months. The results of canonical correspondence analysis showed that individuals of S. bicuspis were more abundant at higher temperatures and lower conductivity than C. incisa. Further research is needed to clarify the observed negative correlation between floating vegetation dry weight and ostracod density and the possible differential thermal preference of the two species studied.     

Species richness of microcrustacea in subterranean freshwater habitats. Comparative analysis and approximate evaluation

Among terrestrial biomes the groundwater domain is generally considered to be a species poor environment. This view results, mainly, from the large geographic scale faunistic surveys (tens and hundreds of kilometres) and the traditionally coarse spatial scale (i.e. macroscale level) of ecological analysis. This view has been challenged by Margalef (1993) who suggests that high diversities are to be expected in the subterranean environment comparable to those found in the deep sea because of environmental similarities, e.g. low energetic resources. During the last twenty years long-term ecological research on much smaller scales, i.e. metres to hundred metres for interstitial media, a mesoscale approach, or kilometre size for karst systems was carried on. Long-term projects on limnic subsurface systems have shown that the species richness (SR) of the microcrustacea (Harpacticoida, Cyclopopoida, Ostracoda) is much higher than previously considered. Details on Harpacticoida of the alluvial bedsediments of a Pyreneean brook, the Lachein, and on Ostracoda of the alluvial sediments of the Danube plain (the phreatic zone), near Vienna, are presented. The SR values of the interstitial microcrustacea obtained through investigations at a mesoscale level are comparable to those of karstic and/or surface freshwater benthic water systems; they are lower than those of the deep-sea data sets for equivalent crustacean groups at a similar scale of investigation. From the data presented we infer the following points: (a) The subterranean waters are much more rich in species than earlier accepted, at least for some organismic groups like the microcrustacean copepods and ostracods. (b) Hence, to describe the still unknown fauna it is appropriate to sample the subsurface waters at an ecological scale. (c) Only studies during long-term ecological projects and with intensive, quantitative, sampling programmes allow a correct evaluation of the subterranean faunal diversity. (d) The species richness of a given subsurface site is strongly dependent on the structure of the habitats and the functioning of the underlying ecosystems. (e) Finally we consider the rationale for the protection of the subterranean faunal diversity.     

Biostratigraphy and Paleobiogeographic implications of the Cenomanian–Early Turonian Ostracods of Egypt

The present study deals with the Cenomanian–early Turonian ostracods in the southern Sinai, Egypt. The investigated sequence includes the Raha and Abu Qada formations. The Raha Formation consists of distinctive Cenomanian taxa such as Cytherella aegyptiensis, Veeniacythereis maghrebensis, V. jezzineensis, V. streblolophata streblolophata, Monoceratina trituberculata, and Glenocythere reticulata. Based on the ostracod species, four local biozones are recognized, including Veeniacythereis jezzineensis – Metacythereopteron berbericum, Cytherella eosulcata – Xestoleberis derorimensis, Amphicytherura ziregensis and Perissocytheridea istriana – Cythereis fahrioni. The paleobiogeography of the considered ostracods suggests that there are two bioprovinces, the first of which is the North African province and includes Egypt, Tunisia and Algeria. The second bioprovince represents the Middle East province and includes Lebanon, Oman and Iran. The strong resemblance between the two bioprovince indicates a relatively good communication along the margin of Southern Tethys during the Cenomanian and improved marine ostracod exchange.     

Middle Permian ostracod fauna from the Khao Khad Formation (Indochina Terrane), Central Thailand

Permian ostracods are reported for the first time from the Wordian (Middle Permian) Khao Khad Formation of Saraburi Group (Lopburi Province, Central Thailand). The ostracod fauna consists of 18 species belonging to 11 genera including Bairdia, Bohlenatia, Liuzhinia, Silenites, Acratia, Bairdiacypris, Basslerella, Aurigerites, Microcheilinella, Paraparchites and Shemonaella. The studied Khao Khad Limestone, which are rich in fusulinids, gastropods, ostracods, bivalves and brachiopods, was deposited in a shallow carbonate platform on the western margin of the Indochina Terrane. The ostracod assemblage is typically Palaeo-Tethyan and similar to faunas from the other Lower to Middle Permian limestones in central Thailand.     

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.     

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.     

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.     

Ostracoda and Mollusca biodiversity and hydrochemical features in Late Miocene brackish basins of Italy

Late Miocene brackish ostracods and molluscs collected in three Italian basins show noticeable differences in their taxonomic composition, despite their capability of dispersing across wide geographic areas. In the Venetian-Friulian Basin (northern Italy), the upper Tortonian sediments contain oligotypic ostracod assemblages including Hemicyprideis dacica dacica, Hemicytheria pejinovicensis, and Loxoconcha cf. L. josephi and few gastropods referable to Planorbidae and Stenothyroides, which are typical of the central Paratethys. In central Italy, the brackish ostracods and molluscs recovered from upper Tortonian-lower Messinian deposits from four Tuscan basins (Volterra-Radicondoli, Velona, Baccinello-Cinigiano, and Valdelsa) display high affinity at a generic level but strong endemicity at a specific level. At Cessaniti (southern Italy), the upper Tortonian unit contains oligotypic brackish ostracods and molluscs: Mediocytherideis (Sylvestra) posterobursa, Cyprideis ruggierii, Loxoconcha cf. L. biformata, and Zonocypris membranae quadricella characterise the ostracod fauna, while Granulolabium bicinctum and Hydrobia frauenfeldi are the dominant molluscs. The recovered ostracods have a strong affinity with brackish species from central and eastern Palaeo-Mediterranean areas, whereas the molluscs present a Paratethyan origin. Despite the fact that the basins are all brackish and partly coeval, the systematics of these assemblages highlights the absence of common species among the three studied areas. Geochemical analyses (stable isotopes and trace elements) are performed on ostracods, and ⁸⁷Sr/⁸⁶Sr ratios are established in molluscs and echinoids. The results suggest brackish environments with different compositions and origins of solutes in the three different areas. The Tuscan basins are characterised by brackish waters, with NaCl-enriched waters coming from aquifers of Triassic evaporite bedrock. The brackish deposits of the Venetian-Friulian Basin and Cessaniti are true marginal marine environments, although the northern basin may have been influenced by both the Paratethyan Sava Basin and the northern portion of the Palaeo-Mediterranean water bodies.     

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.     

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.