Environmental and Seasonal Effects on Gerridae Assemblages (Heteroptera: Gerromorpha) from a Stream in Brazilian Savannah.

Our aim here was to assess the seasonal (dry, ebb, and rainy seasons), spatial (upstream, intermediate, and downstream), and environmental effects on the dynamics of Gerridae assemblages (Heteroptera: Gerromorpha) in a Cerrado stream, in central-western Brazil. We sampled the insects on the water line between May 2011 and April 2014 with an 18 cm diameter sieve. We used the scanning method in 100 m of stream in each sampled locality. We sampled 3690 individuals of 19 species. There was a seasonal difference in abundance, which was a result of a lower abundance in the rainy season, but this did not differ between different environments. The estimated species richness was lower upstream and in the rainy season. Species composition was different between the upstream and downstream portions. It was also different among all seasons, with the greatest difference occurring between the rainy and dry seasons. The abiotic factors were responsible for structuring the assemblages in different seasons. The observed differences among seasons in abundance, richness, and species composition have implications for conservation since changes in the structure of the vegetation in the stream edges change the hydrological cycle of streams, and consequently the diversity of the Gerridae assemblages. There was variation in richness and composition between such small distances (upstream and downstream). This shows how sensitive this system can be, and how important elements of the stream's trophic, with the Gerromorpha, can be easily altered.

Sampling efficiency of a protocol to measure Odonata diversity in tropical streams.

Odonata can be sampled following different types of protocols. In Brazil, the most used protocol is the scanning in fixed areas method, where a 100-meter transect is delimited in one of the stream margins, subdivided into 20 segments measuring 5 meters. Despite being universally used, the methodological efficiency or limitations of this protocol for Odonata has never been tested. In this scenario, our objective was to assess the efficiency of the sampling protocol to measure the richness and composition of Odonata in three fundamental aspects: the time of sampling and sampling effort over time and space. We show that the best sampling efficiency was achieved in collections performed at noon, in transects measuring 100 meters, requiring at least two samplings in the same location, supporting the procedures traditionally adopted by many studies with the group. While comparing species composition, we did not see any implication between the different treatments on the capture of the local species pool. However, we highlight and discuss some possible methodological flaws when using this protocol to sample specific Odonata groups. We believe the results obtained are fundamental in the inventory of species and to conduct future studies, as well as to aid conservative measures that use the order Odonata as a tool for environmental monitoring.

Community assembly of adult odonates in tropical streams: an ecophysiological hypothesis.

Community assembly theory is founded on the premise that the relative importance of local environmental processes and dispersal shapes the compositional structure of metacommunities. The species sorting model predicts that assemblages are dominated by the environmental filtering of species that are readily able to disperse to suitable sites. We propose an ecophysiological hypothesis (EH) for the mechanism underlying the organization of species-sorting odonate metacommunities based on the interplay of thermoregulation, body size and the degree of sunlight availability in small-to-medium tropical streams. Due to thermoregulatory restrictions, the EH predicts (i) that larger species are disfavored in small streams and (ii) that streams exhibit a nested compositional pattern characterized by species' size distribution. To test the EH, we evaluate the longitudinal distribution of adult Odonata at 19 sites in 1st- to 6th-order streams in the Tropical Cerrado of Brazil. With increasing channel width, the total abundance and species richness of Anisoptera increased, while the abundance of Zygoptera decreased. The first axis of an ordination analysis of the species abundance data was directly related to channel width. Mean and maximum thorax size are positively correlated to channel width, but no relationship was found for the minimum thorax size, suggesting that there is no lower size constraint on the occurrence of these species. Additionally, a nested compositional pattern related to body size was observed. Our results support the EH and its use as an ecological assembly rule based on abiotic factors. Forest cover functions as a filter to determine which species successfully colonize a given site within a metacommunity. As a consequence, the EH also indicates higher treats for small-bodied zygopterans in relation to the loss of riparian forests in tropical streams.

Taxonomic and numerical resolutions of nepomorpha (insecta: heteroptera) in cerrado streams.

Transformations of natural landscapes and their biodiversity have become increasingly dramatic and intense, creating a demand for rapid and inexpensive methods to assess and monitor ecosystems, especially the most vulnerable ones, such as aquatic systems. The speed with which surveys can collect, identify, and describe ecological patterns is much slower than that of the loss of biodiversity. Thus, there is a tendency for higher-level taxonomic identification to be used, a practice that is justified by factors such as the cost-benefit ratio, and the lack of taxonomists and reliable information on species distributions and diversity. However, most of these studies do not evaluate the degree of representativeness obtained by different taxonomic resolutions. Given this demand, the present study aims to investigate the congruence between species-level and genus-level data for the infraorder Nepomorpha, based on taxonomic and numerical resolutions. We collected specimens of aquatic Nepomorpha from five streams of first to fourth order of magnitude in the Pindaíba River Basin in the Cerrado of the state of Mato Grosso, Brazil, totaling 20 sites. A principal coordinates analysis (PCoA) applied to the data indicated that species-level and genus-level abundances were relatively similar (>80% similarity), although this similarity was reduced when compared with the presence/absence of genera (R = 0.77). The presence/absence ordinations of species and genera were similar to those recorded for their abundances (R = 0.95 and R = 0.74, respectively). The results indicate that analyses at the genus level may be used instead of species, given a loss of information of 11 to 19%, although congruence is higher when using abundance data instead of presence/absence. This analysis confirms that the use of the genus level data is a safe shortcut for environmental monitoring studies, although this approach must be treated with caution when the objectives include conservation actions, and faunal complementarity and/or inventories.

Composição e riqueza de Odonata (Insecta) em riachos com diferentes níveis de conservação em um ecótone Cerrado-Floresta Amazônica / Composition and richness of Odonata (Insecta) in streams with different levels of conservation in a Cerrado-Amazonian Forest ecotone

The removal or substitution of riparian vegetation causes disturbance in physical environment, seasonal water flow and water chemical quality. These modifications can cause decrease in species richness by local extinctions. The aim of this study was to examine the effect of disturbance in the physical environmental on the richness and species composition of Odonata adults in streams with different levels of conservation in the river Suiá-Missu basin, Mato Grosso, Brazil. Modifications in the aquatic systems affected the Odonata community, probably because their ecophysiological and behavioral requirements of adults and larvae. Anisoptera species, which require sunny environments because of their body size, had higher species richness in environments with low plant cover. On the other hand, Zygoptera species, which generally inhabit streams with dense vegetation, presented a decrease in richness in disturbed environments, as a result high sunlight radiation and/or variations in temperature. Hence, in both suborders, environmental perturbations do not need to be severe to change species composition, indicating that ecosystem services could be lost, even with only partial alterations in physical environment.

A retirada ou a substituição da vegetação ripária provoca uma alteração no ambiente físico, no fluxo sazonal e na qualidade química da água. Essas modificações podem causar a diminuição da riqueza pela extinção local de espécies. O objetivo deste trabalho foi avaliar o efeito do distúrbio da integridade ambiental sobre a riqueza e composição de espécies de Odonata adultos em córregos com diferentes níveis de conservação, na Bacia do Rio Suiá-Missu, Mato Grosso, Brasil. As modificações nos sistemas aquáticos afetaram a comunidade de Odonata, provavelmente devido às exigências ecofisiológicas e comportamentais relacionadas a adultos e larvas. Anisoptera, que necessitam de ambientes com maior incidência de sol devido ao tamanho do corpo, apresentaram maior riqueza de espécies em ambientes com menor cobertura vegetal. Por outro lado, os Zygoptera geralmente habitam riachos com cobertura vegetal mais densa, e por isso, apresentaram um decréscimo de sua riqueza em locais alterados, devido à maior entrada de luz e/ou variação do calor. Assim, para as duas subordens, as alterações ambientais não precisam ser severas para produzir modificações significativas na composição, indicando que os serviços ecossistêmicos poderiam ser perdidos, mesmo com alterações parciais do meio físico.

Gerromorpha (Hemiptera: Heteroptera) of eastern Mato Grosso State, Brazil: checklist, new records, and species distribution modeling.

The infraorder Gerromorpha comprises semiaquatic bugs, most of which spend much of their lifetime on the water surface, between floating plants, or on the margins of water bodies. Based on literature and collections made on streams and lakes on municipalities of eastern Mato Grosso, Brazil, a list has been elaborated with 52 species, including several new records. Out of the recorded species, 26 belong to the family Veliidae, 20 to Gerridae, three to Hydrometridae, two to Mesoveliidae, and one to Hebridae. The modeling of the potential geographical distribution is also presented for the 20 species that have been recorded for the first time from the state.

Ephemeroptera (Insecta) ocorrentes no leste do Estado do Mato Grosso, Brasil / Ephemeroptera (Insecta) from east of Mato Grosso State, Brazil

Com o objetivo de apresentar um levantamento da fauna de Ephemeroptera no Estado do Mato Grosso, investigamos as ninfas de Ephemeroptera, principalmente de duas bacias hidrográficas do leste do estado. Sessenta e sete espécies/morfoespécies em 41 gêneros e oito famílias foram encontradas. Quatro espécies (Cloeodes redactus Waltz & McCafferty, 1987 e Waltzoyphius roberti Thomas & Peru, 2002 [Baetidae], Tricorytopsis chiriguano Molineri, 2001 [Leptohyphidae] e Microphlebia surinamensis Savage & Peters, 1983 [Leptophlebiidae]) foram registradas pela primeira vez no Brasil. As famílias Euthyplociidae, Polymitarcyidae e Coryphoridae foram registradas pela primeira vez para o Mato Grosso, assim como 19 gêneros e 18 espécies. Vinte e cinco espécies não foram identificadas devido à falta de informação envolvendo o estágio ninfal de seus respectivos gêneros. Assim como demonstrado em outros trabalhos com o grupo, a ordem se mostrou mais diversa do que se conhece atualmente, especialmente se considerarmos as várias fisionomias e bacias hidrográficas do estado que se mantêm desconhecidas.

Aiming to present a survey of Ephemeroptera fauna of Ephemeroptera from Mato Grosso State we investigated mayfly nymphs mainly from two hydrographic basins located in the eastern area of the state. Sixty-seven species/morphospecies in 41 genera and eight families were encountered. Four species (Cloeodes redactus Waltz & McCafferty, 1987 and Waltzoyphius roberti Thomas & Peru, 2002 [Baetidae], Tricorytopsis chiriguano Molineri, 2001 [Leptohyphidae] and Microphlebia surinamensis Savage & Peters, 1983 [Leptophlebiidae]) are recorded for the first time from Brazil. The families Euthyplociidae, Polymitarcyidae and Coryphoridae are recorded for the first time from Mato Grosso, as well as 19 genera and 18 species. Twenty-five species could not be identified due to the lack of knowledge regarding the nymphal stage of their respective genera. As demonstrated in others surveys of mayflies in Brazil, the order is much more diverse than currently recognized, especially if we consider that several physiognomies and hydrographic basins of the state remain undocumented.

Novos registros e notas sobre distribuição geográfica de Trichoptera Kirby, 1813 (Insecta) do Estado de Mato Grosso, Brasil / New records and notes on geographic distribution of Trichoptera Kirby, 1813 (Insecta) from Mato Grosso State, Brazil

Trichoptera comprise one of the most diverse and abundant group among aquatic insects in stream ecosystems around the world. Currently, about 500 species are known from Brazil, but only sixteen species have been recorded from the State of Mato Grosso. The present article provides a list of known species and new records of caddisflies collected in the eastern region over the past 10 years and incorporated in the entomological section of the Coleção Zoobotânica "James A. Ratter" of University of Mato Grosso State, Nova Xavantina (CZNX). Specimens were recorded from tributaries of the Rio Xingu and of the Rio das Mortes and from lakes and rivers of the Bananal floodplain. Altogether, 30 species are reported, being seven new records from Mato Grosso. Achoropsyche duodencimpunctata (Navás, 1916), Amazonatolica hamadae Holzenthal & Pes, 2004, Nectopsyche nigricapilla (Navás, 1920), Nectopsyche quatourguttata (Navás, 1922), Macronema hageni Banks, 1924, Macrostemum santaeritae (Ulmer, 1905) and Cyrnellus fraternus (Banks, 1905) are new records from the State. Nectopsyche quatourguttata and N. nigricapilla configure the first records to Brazil. Additionally, Blepharopus diaphanus Kolenati, 1859, Macrostemum arcuatum (Erichson, 1848), Macrostemum ulmeri (Banks, 1913) are new regional records and provide additional material to species distribution from State.

A ordem Trichoptera compreende uma das mais diversas e abundantes ordens dentre todos os grupos de insetos aquáticos encontrados em rios ao redor do mundo. Atualmente, cerca de 500 espécies são conhecidas no Brasil, mas apenas 16 espécies foram registradas para o Estado de Mato Grosso. O presente estudo apresenta uma lista das espécies conhecidas e novos registros, a partir de material coletado na região leste do estado nos últimos 10 anos e incorporado à seção entomológica da Coleção Zoobotânica "James A. Ratter" da Universidade do Estado de Mato Grosso, Nova Xavantina (CZNX). Foram registrados espécimes de tributários do Rio Xingu e do médio Rio das Mortes e em lagos e rios da planície de inundação do Bananal. Ao todo são reportadas 30 espécies, sendo sete novos registros para o Estado de Mato Grosso. Achoropsyche duodencimpunctata (Navás, 1916), Amazonatolica hamadae Holzenthal & Pes, 2004, Nectopsyche nigricapilla (Navás, 1920), Nectopsyche quatourguttata (Navás, 1922), Macronema hageni Banks, 1924, Macrostemum santaeritae (Ulmer, 1905) e Cyrnellus fraternus (Banks, 1905) são novos registros para Mato Grosso. Nectopsyche quatourguttata e N. nigricapilla são registradas pela primeira vez para o Brasil. Adicionalmente, Blepharopus diaphanus Kolenati, 1859, Macrostemum arcuatum (Erichson, 1848) e Macrostemum ulmeri (Banks, 1913) configuram novos registros regionais e provêem material adicional para a distribuição das espécies no Estado.