On a new tribe, genus and species of Cypricercinae McKenzie, 1971 (Crustacea, Ostracoda, Cyprididae) from New Caledonia (Pacific Ocean)

The New Caledonian Archipelago is a hot spot for biodiversity and endemism. Here, we describe Lithocypris peyia gen. et spec. nov. Martens, Almeida & Higuti from a single locality (a lithotelma, or rockpool) on Grande Terre, the main island of the archipelago. The new genus belongs to the subfamily Cypricercinae and to the new tribe Lithocypridini trib. nov. based on the absence of a groove and anterior inner lists in the left valve, on several aspects of the chaetotaxy, of the prehensile palps and of the hemipenis, and on the fact that the Triebels Loop is situated in the dorsal branch of the attachment of the caudal ramus. Lithocypris gen. nov. can further be distinguished from the other genera in the subfamily by a combination of features: carapace elongated in lateral view and narrow in dorsal view, left valve with a weak ventral and posterior inner list only, antennule with both Wouters and Rome organs, maxillula with elongated and rectangular second palp segment and very short sideways directed bristles, first thoracopod with setae a, b and d present and with female palp short and plump, second thoracopod with setae d1 and d2 very short, third thoracopod with seta f missing and Zenker organ with a crown.

An updated checklist of recent non-marine Ostracoda (Crustacea) from Venezuela

Information on the known species diversity of the non-marine ostracods in Venezuela is compiled from the available literature. The review resulted in 34 species and two varieties, belonging to the superfamilies Cypridoidea and Cytheroidea. Of these, the presence of one species should be confirmed for the country. Furthermore, eight taxonomic entities classified with open nomenclature are mentioned. As additional contributions to the annotated list, georeferences of the records are included, as well as amendments in names and information for some localities. Finally, information about the distribution of some species, which were erroneously assigned to other biogeographic areas, is clarified, which is essential to optimizing the accuracy of subsequent analyses.

On a new genus and four new species of the subfamily Cyprettinae (Crustacea, Ostracoda) from Brazilian floodplains

We describe the new genus Triangocypretta gen. nov. and four new species from Brazilian floodplains. Triangocypretta angustus gen. et spec. nov. and Triangocypretta labiata gen. et spec. nov. were described from the Amazon floodplain only, while Triangocypretta nates gen. et spec. nov. was described from Amazon, Araguaia, and Paran River floodplains. Triangocypretta hirsuta gen. et spec. nov. was recorded from all four floodplains: Amazon, Araguaia, Pantanal and Paran. The new genus is characterized by the triangular shape of the carapace in lateral view, the absence of teeth on the posteroventral inner list in the right valve and the presence of anterior marginal septa in both valves, as well as by the relatively short and thin and -setae on the mandibular palp. All populations found were asexual. Owing to the clear differences in valve anatomy and limb chaetotaxy as compared to species of Cypretta s.s., the four species were allocated to a new genus in the subfamily Cyprettinae.

An annotated checklist of recent non-marine Ostracoda (Crustacea) from Argentina, South America

According to an updated list of extant non-marine ostracods, there are 2,330 subjective species in 270 genera in the world, of which 333 species are known from the Neotropical region. However, the knowledge about the ostracod fauna in Argentina is scarce, fragmented and incomplete. Thus, the aim of this study was to present the first checklist of the recent non-marine ostracods from Argentina, including geographical distributions and ecological characteristics of the species. Thus far, 66 ostracod species in 33 genera and 7 families have been recorded in non-marine Argentinian environments. Of the total number of species, 29% can be considered endemic to the country. Most of the species were recorded in alkaline, freshwater to oligohaline cold waters and mainly in low to moderate altitude environments. Our results showed that most studies were mainly carried out in the Pampean and Patagonia region and, therefore, the diversity record of ostracods in Argentina is biased towards these regions.

On Caledromusrobinsmithi, a new genus and species of Psychrodromini Martens, 2001 (Crustacea, Ostracoda, Herpetocypridinae) from New Caledonia (Pacific Ocean)

The New Caledonian Archipelago is a hot spot for biodiversity and endemism. Whereas popular groups such as birds and plants are well-studied, invertebrate groups such as ostracods remain ill-known. Here, Caledromusrobinsmithigen. et sp. nov. is described from a single locality on 'Grande Terre', the main island of the archipelago. The new genus belongs to the Psychrodromini, one of the four tribes in the subfamily Herpetocypridinae (family Cyprididae). Caledromusgen. nov. can be distinguished from all other herpetocypridinids by a combination of the following factors: the absence of marginal septa in both valves, the mildly developed marginal valve structures, the small Rome organ on the A1, the total reduction of the five natatory setae on the A2, the rectangular second palp segment of the Mx1, the broad and asymmetrical palp on the female T1, the absence of additional postlabyrinthal coils in the Hp and the seta Sp of the CR which is a fixed spine. Because of the close similarity to the genus Psychrodromus, the new genus is thought to have Palaearctic affinities, contrary to other ostracod species in New Caledonia, which are either circumtropical or with Australian zoogeographical connections.

On a New Species of Pseudocypretta Klie, 1932 (Crustacea, Ostracoda) from the Neotropical Region, with a Discussion on the Position of the Genus

Pseudocypretta amor sp. nov. (named after the carapace spots resembling the word "Love") is here described from all-female populations from the four major floodplains in Brazil. The new species is compared to the other two known species in the genus, P. maculata Klie (1932), the type species, and P. lineata Ma and Yu (2020). As the latter two species are thus far found exclusively in South East Asia and China, respectively, the present extension of the area of the genus to South America is considerable. Several morphological characters in this genus and species are discussed, especially the presence of marginal septa in the valves, the candonid type T3 with 3^rd and 4^th segment separated (candonid type) and the caudal ramus which is reduced to a flagellum (cypridopsine type) or is fully absent. Based on the combination of these and other characters, the genus Pseudocypretta is here transferred from the Cyprettinae to the tribe Cyprettadopsini in the Cypridopsinae, as it is closely related to the genus Cyprettadopsis Savatenalinton, 2020. The presence of the candonid type T3 in Cyprididae and Notodromadidae, where the T3 generally has a pincer-shaped tip by the fusion of the 3^rd and the 4^th segment, is further discussed.

Water chemistry and not urbanization influences community structure of non-marine Ostracoda (Crustacea) in northern Belgium

Urbanization is one of the major causes of the destruction of natural habitats in the world. Cities are urban heat islands and can thus significantly influence populations of plants and animals. The research project SPEEDY investigated the effects of urbanization in northern Belgium with a nested sampling design at local and landscape scales for a variety of organisms. Here, we tested the effects of urbanization on non-marine ostracod communities, sampling 81 small pools in three urbanization categories, as defined by percentage built up cover (low, intermediate, high). We identified 17 ostracod species, together occurring in 60 of the 81 sampled pools. We found that urbanization per se had no significant effect on ostracod communities. Of all the measured local factors, ammonium and total phosphorus concentrations had a significant effect on the community structure. In contrast, water temperature had no significant effect, most likely because the ostracod species found in northern Belgium in the present survey mostly have wide temperature tolerances.

On two new species of Cypricercus Sars, 1895 (Crustacea, Ostracoda) from Brazil with a discussion on the taxonomy of the genus

We describe two new species of Cypricercus, Cypricercus alfredo sp. nov. and Cypricercus tiao sp. nov., and briefly redescribe the female of Cypricercus centrurus (Klie, 1940) from Brazilian floodplains. Both new species have the elongated carapace which is characteristic of the genus. Cypricercus alfredo sp. nov. was found as both sexual and asexual populations and has a posterior spine on the right valve and differs from the Brazilian C. centrurus by the position and the size of spine and the size and shape of the carapace. Cypricercus tiao sp. nov. was found as one asexual population only and lacks a posterior spine on the right valve. Cypricercus populations in Brazil mostly consist exclusively of asexual females, but some sexual populations and populations with mixed reproduction can also be found. This genus occurs primarily in the Southern Hemisphere, but some species can also be found in the southern part of North America and in India. We also present a re-appraisal of all species presently allocated to the genus, primarily based on original descriptions.

Taxonomic revision of Strandesia s.s. (Crustacea, Ostracoda) from four Brazilian floodplains, with the description of three new species

The present paper is a contribution to the taxonomy of the genus Strandesia. Here, we describe three new species: S. thomazi nov. sp., S. galeati nov. sp. and S. nakatanii nov. sp. We also describe the male of Strandesia obtusata (Sars, 1901); this is the first record of sexual populations of a Brazilian Strandesia species. Nine other Strandesia species from the Amazon, Araguaia, Pantanal and Paraná river floodplains are redescribed. We also propose that Strandesia trichosa Roessler, 1990 is a synonym of Strandesia psittacea Sars, 1901. Most of the species analyzed here are endemic to the Neotropical region, with the exception of Strandesia bicuspis (Claus, 1892) G.W. Müller, which occurs also (as an alien invasive species) in the Palaearctic. This genus occurs in water bodies with a wide range of abiotic variables and in many different aquatic macrophyte species. The species analyzed here have a highly conservative soft part morphology, but an impressive variety of carapace shapes.

Urbanization drives cross-taxon declines in abundance and diversity at multiple spatial scales

The increasing urbanization process is hypothesized to drastically alter (semi-)natural environments with a concomitant major decline in species abundance and diversity. Yet, studies on this effect of urbanization, and the spatial scale at which it acts, are at present inconclusive due to the large heterogeneity in taxonomic groups and spatial scales at which this relationship has been investigated among studies. Comprehensive studies analysing this relationship across multiple animal groups and at multiple spatial scales are rare, hampering the assessment of how biodiversity generally responds to urbanization. We studied aquatic (cladocerans), limno-terrestrial (bdelloid rotifers) and terrestrial (butterflies, ground beetles, ground- and web spiders, macro-moths, orthopterans and snails) invertebrate groups using a hierarchical spatial design, wherein three local-scale (200 m × 200 m) urbanization levels were repeatedly sampled across three landscape-scale (3 km × 3 km) urbanization levels. We tested for local and landscape urbanization effects on abundance and species richness of each group, whereby total richness was partitioned into the average richness of local communities and the richness due to variation among local communities. Abundances of the terrestrial active dispersers declined in response to local urbanization, with reductions up to 85% for butterflies, while passive dispersers did not show any clear trend. Species richness also declined with increasing levels of urbanization, but responses were highly heterogeneous among the different groups with respect to the richness component and the spatial scale at which urbanization impacts richness. Depending on the group, species richness declined due to biotic homogenization and/or local species loss. This resulted in an overall decrease in total richness across groups in urban areas. These results provide strong support to the general negative impact of urbanization on abundance and species richness within habitat patches and highlight the importance of considering multiple spatial scales and taxa to assess the impacts of urbanization on biodiversity.

A global database for metacommunity ecology, integrating species, traits, environment and space

The use of functional information in the form of species traits plays an important role in explaining biodiversity patterns and responses to environmental changes. Although relationships between species composition, their traits, and the environment have been extensively studied on a case-by-case basis, results are variable, and it remains unclear how generalizable these relationships are across ecosystems, taxa and spatial scales. To address this gap, we collated 80 datasets from trait-based studies into a global database for metaCommunity Ecology: Species, Traits, Environment and Space; "CESTES". Each dataset includes four matrices: species community abundances or presences/absences across multiple sites, species trait information, environmental variables and spatial coordinates of the sampling sites. The CESTES database is a live database: it will be maintained and expanded in the future as new datasets become available. By its harmonized structure, and the diversity of ecosystem types, taxonomic groups, and spatial scales it covers, the CESTES database provides an important opportunity for synthetic trait-based research in community ecology.

Unified Multimetric Index for the Evaluation of the Biological Condition of Streams in Southern Brazil Based on Fish and Macroinvertebrate Assemblages

We developed MMI models that combine responses of fish and benthic macroinvertebrates for the evaluation of the biotic integrity of streams. The MMI was developed using a dataset covering stream sampling sites in the South of Brazil. Reference streams were identified based on the physical and chemical conditions and riparian vegetation. Thirty-four metrics were calculated and evaluated for their range, redundancy, and responsiveness to the environmental perturbation. We applied a robust approach to select the most sensitive metrics and MMI models based on the complexity and ability of the index in distinguishing impacted and reference sites. The four best MMI models selected are composed of different combinations of the eight metrics: % fish herbivorous, fish evenness, fish abundance, % macroinvertebrate shredder; % macroinvertebrate predator; % macroinvertebrate tolerant, % macroinvertebrate swimmer, and % macroinvertebrate burrower. All of the MMI models selected presented good performance in distinguishing reference streams from those impacted by different forms of land use. This study is one of the few attempts to use more than one biological assemblage in a single-multimetric index. Accordingly, we believe that the unified MMI we developed could be a useful tool to assist in the conservation and management of water resources in Neotropical regions, specially, in the implementation of ecological integrity tools more cost-effectively.

Body-size shifts in aquatic and terrestrial urban communities

Body size is intrinsically linked to metabolic rate and life-history traits, and is a crucial determinant of food webs and community dynamics^1,2. The increased temperatures associated with the urban-heat-island effect result in increased metabolic costs and are expected to drive shifts to smaller body sizes ³ . Urban environments are, however, also characterized by substantial habitat fragmentation ⁴ , which favours mobile species. Here, using a replicated, spatially nested sampling design across ten animal taxonomic groups, we show that urban communities generally consist of smaller species. In addition, although we show urban warming for three habitat types and associated reduced community-weighted mean body sizes for four taxa, three taxa display a shift to larger species along the urbanization gradients. Our results show that the general trend towards smaller-sized species is overruled by filtering for larger species when there is positive covariation between size and dispersal, a process that can mitigate the low connectivity of ecological resources in urban settings ⁵ . We thus demonstrate that the urban-heat-island effect and urban habitat fragmentation are associated with contrasting community-level shifts in body size that critically depend on the association between body size and dispersal. Because body size determines the structure and dynamics of ecological networks ¹ , such shifts may affect urban ecosystem function.

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

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

Checklist de ostrácodes (Crustacea, Ostracoda) dulcícolas do Pantanal Sul Mato-grossense, Brasil

RESUMO Atualmente existem cerca de 2.000 espécies de Ostracoda dulcícolas descritas em diversos ambientes aquáticos do mundo, das quais cerca de 117 espécies em aproximadamente 37 gêneros são conhecidas no Brasil. O presente levantamento de ostrácodes do Pantanal Sul Mato-grossense, registrou 35 espécies pertencentes às famílias Cyprididae, Candonidae, Limnocytheridae e Darwinulidae. A fauna de ostrácodes do Brasil ainda é pouco conhecida e a biodiversidade de ostrácodes de vários habitats (por exemplo, instersticial) ainda permanecem desconhecidos. Neste sentido, existe grande probabilidade de se encontrar novos registros e novos táxons de ostrácodes no Pantanal, assim como em todo território brasileiro.

Effect of land use on the composition, diversity and abundance of insects drifting in neotropical streams

Abstract Streams may exhibit differences in community structure of invertebrate drift, which may be a reflex of variation in environmental factors, able to change in conditions of anthropogenic interventions. The aim of this study was to analyze the composition, diversity and abundance of insects drifting in two neotropical streams under different land use and to identify the environmental factors involved in determining such patterns. 54 taxa of aquatic insects were identified in urban and rural streams. The results indicated significant differences in species composition due to the replacement of specialist species by generalist species in the urban stream. Higher diversity of taxa was recorded in the rural stream, with high levels of dissolved oxygen and high water flow, which favored the occurrence of sensitive groups to environmental disturbances, such as Ephemeroptera, Plecoptera, Trichoptera and Coleoptera taxa, that living mainly in clean and well oxygenated waters. On the other hand, a higher density of insects drifting, especially Chironomidae, was observed in the urban stream, where high values of pH, electrical conductivity and nitrogen were observed. These larvae are able to explore a wide range of environmental conditions, owing to their great capacity for physiological adaptation. Despite observing the expected patterns, there were no significant differences between streams for the diversity and abundance of species. Thus, the species composition can be considered as the best predictor of impacts on the drifting insect community.

Does the habitat structure control the distribution and diversity of the Odonatofauna?

AbstractThe statement that the habitat complexity and structure govern the abundance and diversity of biological communities has been widely investigated. In this context, we assumed the hypothesis of habitat heterogeneity, that is, the higher habitat complexity leads to greater diversity of Odonata. In addition, we analyzed the influence of habitat structure on the distribution of this community, and evaluated the effects of abiotic variables. Odonata larvae were collected with sieves and by electrofishing in ten neotropical streams belonging to the Pirapó River basin. Forty species of Odonata were registered, which were distributed in eight families, Libellulidae stood out with the highest richness. The high gamma diversity and distribution of Odonata were associated with habitat heterogeneity in these streams. However, the abiotic variables also seem to affect the distribution of Odonata species, in view of the impact of the land use in the vicinity of streams.

Beta diversity as a tool for determining priority streams for management actions

Beta diversity has become essential for understanding ecosystem functioning and for determining biodiversity-conservation priority areas. However, the beta diversity patterns of invertebrates in tropical aquatic ecosystems are not well known, particularly in streams. Using data from low-order streams located in southern Brazil, we evaluated the beta diversity of Chironomidae. We tested the hypothesis that increased environmental heterogeneity increases beta diversity. The streams were grouped into two categories, rural and urban, according to the percentage of urbanization in their micro-basins. Our results showed that the heterogeneity of environmental variables can determine the beta diversity of Chironomidae, and the increased environmental heterogeneity caused by differences in the intensity of urbanization impacts can increase the beta diversity in urban streams. Therefore, the intensified impacts of anthropogenic activities in aquatic ecosystems can also increase beta diversity. Finally, we suggested that beta diversity can be an effective tool for not only designing measures and determining priority conservation areas, but also accurately identifying potentially degraded and priority sites that require water management plans.

Percentage of Impervious Surface Soil as Indicator of Urbanization Impacts in Neotropical Aquatic Insects

Several recent studies have shown a strong correlation between the area of impervious surface soil (IS) and the insect community structure from urban streams. This study assessed whether this relationship is observed in Neotropical streams. We examined if an increased IS reduces the diversity and simplifies the trophic structure of the community of Ephemeroptera, Plecoptera, and Trichoptera. An IS threshold was detected between 1.6 and 9.3%, in which there is a change in the community, both in taxonomic richness and trophic structure. Among the 27 genera identified, only 15 occurred in streams with IS > 9%, while 24 genera were registered in streams with IS < 2%. The trophic guilds of predators and shredders were not observed in streams with high IS, decreasing the number of guilds in these streams from 5 to 3, compared with the streams with low IS. Three hypotheses with cumulative effect have been proposed to explain such variations. Based on the IS threshold verified, the creation of a mosaic of land use, where some subbasins would be sacrificed and others would be preserved, was suggested as a mitigation measure for the impacts caused by urbanization in the Neotropical aquatic insects' fauna.

Diet and feeding selectivity of a benthivorous fish in streams: responses to the effects of urbanization

This study evaluated the diet and feeding selectivity of the catfish Imparfinis mirini in streams with different degrees of urbanization and the effect of rainfall on the availability of prey. The diet was based especially on Chironomidae and Trichoptera. Significant spatial differences in diet were found between the streams; the diet of the fish was similar in the rural and peri-urban streams, and differed from that in the urban stream. Seasonality was an unimportant factor affecting the species' diet, which did not differ significantly between the rainy and dry periods in any of the streams. Fish from the urban stream fed more according to what was available in the environment, while fish from the peri-urban and rural streams showed higher degrees of selectivity. The results indicate that environmental conditions influenced the diet and prey selection of this species in response to the differences in diversity and abundance of the food organisms. They indicate that trophic studies of benthivorous fishes, such as I. mirini, may represent an alternative way to assess human effects on streams.

Benthic macroinvertebrate community structure in a stream of the north-west region of Paraná State, Brazil

This study aimed to survey the benthic macroinvertebrate fauna of a first order stream located in an agricultural area, and to assess the environmental factors involved in the spatial distribution of this community. Invertebrates were gathered in November 2007 at three sampling sites distributed along the Itiz Stream, located in Marialva municipality, Paraná State. At each site, we measured the physical and chemical variables of the water, and then took four samples, using Surber sampler. In order to evaluate the differences in density, richness, diversity and evenness, we employed an ANOVA and a DCA to summarize biotic data. The invertebrates were categorized into functional groups and the BMWP score was applied to calculate the biological integrity of the environment. The faunal composition was represented by 103 taxa distributed across five phyla, of which the highest occurrence was of arthropods, especially insects. Higher density values were observed for Chironomidae, Ephemeroptera, Coleoptera and Trichoptera. The richness, diversity and density, as well as the density of gathering-collectors, were higher in the intermediate course of the stream. The distribution pattern of the taxa was mainly influenced by lentic or lotic characteristics of the sampled sites and microhabitats, as evidenced by the DCA. The BMWP indices indicated that the three sampling sites presented scores of excellent and good water quality. In the Itiz Stream, the presence of preserved marginal vegetation and the distance from urban centers that generate pollution, combined with peculiarities of each sampling site, influenced the structure of the benthic community.

Composition and distribution of Darwinulidae (Crustacea, Ostracoda) in the alluvial valley of the upper Paraná River, Brazil

The occurrence and abundance of darwinulid ostracods, as well as environmental factors influencing these patterns, were investigated in the alluvial valley of the upper Paraná River. Ostracods were sampled from several substrates, like littoral sediments and pleuston, which included several aquatic macrophytes species, from 31 localities (lentic and lotic) belonging to different riverine systems. Eight darwinulid species were found, representing all genera from this family. Alicenula serricaudata, Vestalenula pagliolii, and Penthesilenula brasiliensis were the most common species. Cluster analysis based on the composition and abundance of darwinulid communities revealed the presence of five associations. Darwinula stevensoni, Vestalenula botocuda, and Penthesilenula aotearoa were almost exclusive to lotic environments. A Mantel multiple test showed that the occurrence and distribution of darwinulid ostracods were significantly related to types of habitat and systems, but not to abiotic variables. It thus seems that the hydrodynamic fluctuations of these environments are probably more important to darwinulid distribution than the limnological characteristics.

Biodiversity of non-marine ostracods (Crustacea, Ostracoda) in the alluvial valley of the upper Paraná River, Brazil

In the present study, we test the relevance of a number of environmental factors on alpha and beta ostracod diversities, at species and family level. Ostracods were sampled from several substrates, including sediment and root systems of various floating aquatic macrophytes, from 48 environments (both lentic and lotic habitats, ranging from the river itself, over connecting channels linking with open lakes, and, finally closed lakes), belonging to four different systems (Paraná, Ivinheima, Baía and Taquaruçu), in the alluvial valley of the Upper Paraná River. The faunistic survey recorded the presence of 54 species of Ostracoda, belonging to the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Various diversity estimators indicated that these recorded levels of specific diversity should be close to true values. Higher values of ostracods species richness (alpha diversity) were observed in the Baía and Ivinheima systems, while lotic habitats were richer than lentic ones. In addition, open lakes appeared to be more affected by the variable 'system' than closed ones, which can to some extend be explained by the putative effects of flood pulse on benthic communities. The two investigated factors have different effects on the four ostracod families. The present study also indicated that there is a large homogeneity within and between systems, as exemplified by the low beta-diversity levels.

Biodiversity of non-marine ostracods (Crustacea, Ostracoda) in the alluvial valley of the upper Paraná River, Brazil

In the present study, we test the relevance of a number of environmental factors on alpha and beta ostracod diversities, at species and family level. Ostracods were sampled from several substrates, including sediment and root systems of various floating aquatic macrophytes, from 48 environments (both lentic and lotic habitats, ranging from the river itself, over connecting channels linking with open lakes, and, finally closed lakes), belonging to four different systems (Paraná, Ivinheima, Baía and Taquaruçu), in the alluvial valley of the Upper Paraná River. The faunistic survey recorded the presence of 54 species of Ostracoda, belonging to the families Cyprididae, Candonidae, Limnocytheridae and Darwinulidae. Various diversity estimators indicated that these recorded levels of specific diversity should be close to true values. Higher values of ostracods species richness (alpha diversity) were observed in the Baía and Ivinheima systems, while lotic habitats were richer than lentic ones. In addition, open lakes appeared to be more affected by the variable 'system' than closed ones, which can to some extend be explained by the putative effects of flood pulse on benthic communities. The two investigated factors have different effects on the four ostracod families. The present study also indicated that there is a large homogeneity within and between systems, as exemplified by the low beta-diversity levels.

Spatial and temporal variation in densities of chironomid larvae (Diptera) in two lagoons and two tributaries of the upper Paraná River floodplain, Brazil

Chironomid larvae were collected and abiotic variables measured at monthly intervals at 21 sampling stations in two lagoons (Guaraná and Patos) and two tributaries (Baía and Ivinheima) of the Upper Paraná River floodplain. The genera Procladius, Chironomus, Goeldichironomus, and Polypedilum were dominant in the lagoons and in the Baía River, while Cryptochironomus and Lopescladius were more dominant in the Ivinheima River. The similarity in the generic composition of the chironomids of the lagoons and the Baía River is probably due to the fact that this river presents hydrodynamic characteristics similar to those of the lagoons. The results obtained suggest that the hydrodynamics of these environments are the main factor determining spatial variation in the chironomid fauna. This is intuitively clear, as this factor itself determines sediment type, quantity of organic matter and presence or absence of aquatic macrophytes. However, on a seasonal scale, the flood pulse seems to be the main controlling factor of the temporal variation in densities and dominance of chironomid larvae. Given that this factor has a large influence on the temporal dynamics of several limnological variables, this is again a logical correlation. Our results suggest a strong relationship between the variations in the chironomid community and fluctuations in limnological characteristics.

Cyclopidae (Crustacea, Copepoda) from the upper Paraná River floodplain, Brazil

Cyclopid copepods from samples of fauna associated with aquatic macrophytes and plancton obtained in lotic and lentic environments were obtained from the upper Paraná River floodplain (in the states of Paraná and Mato Grosso do Sul, Brazil). Macrophytes were collected in homogeneous stands and washed. Plankton samples, taken from the water column surface and bottom, were obtained using a motor pump, with a 70 microns mesh plankton net for filtration. Twelve taxa of Cyclopidae were identified. Among them, Macrocyclops albidus albidus, Paracyclops chiltoni, Ectocyclops rubescens, Homocyclops ater, Eucyclops solitarius, Mesocyclops longisetus curvatus, Mesocyclops ogunnus, and Microcyclops finitimus were new finds for this floodplain. Eight species were recorded exclusively in aquatic macrophyte samples. Among these species, M. albidus albidus and M. finitimus presented greatest abundances. Only four species were recorded in plankton samples, and Thermocyclops minutus and Thermocyclops decipiens are limited to this type of habitat. Among these four species, T. minutus is the most abundant, especially in lentic habitats.