Ocorrência de Polypedilum (Tripodura) amataura Bidawid-Kafka, 1996 (Diptera; Chironomidae) em Aquascypha hydrophora (berk.) Reid (Fungi; Stereaceae), com descrição da pupa na Amazônia Central, Brasil

Quatro larvas foram coletadas em água retida pelo fungo Aquascypha hydrophora (Berk.) Reid (Fungi: Stereaceae) fixo em troncos de árvores eretas, na Reserva Florestal Adolpho Ducke, Amazonas, Brasil. Das larvas coletadas, apenas um exemplar desenvolveu até a fase adulta, sendo identificado como Polypedilum (Tripodura) amataura Bidawid-Kafka, 1996. Esta é a primeira descrição para uma forma imatura deste gênero, e também o primeiro registro em micotelmata.

Apedilum griseistriatum comb. nov., placement of Chironomus (Polypedilum) griseistriatum (Diptera, Chironomidae)

The study of the type material of Chironomus (Polypedilum) griseistriatum Edwards, 1931 described from Patagonia lead us to formally transfer the species to Apedilum Townes, 1945 as a new combination, and a reared specimen allows us to describe its pupa. Based on several larvae belonging to Apedilum collected in the proximity of the localities in which the adults and pupae were found, we tentatively describe the larval stage. Subfossil larval head capsules of the same species were found in Laguna Stibnite at 46°S in Chile dated to about 2,500 years ago and in Puerto Blest, Lago Nahuel Huapi at 41°S in Argentina dated about 2,000 years ago. We discuss the habitat of the species based on both modern and subfossil material. Identification keys to male adult, pupae and fourth instar larvae are also provided.

Diet and functional feeding groups of Chironomidae (Diptera) in the Middle Paraná River floodplain (Argentina)

The gut contents of nine genera of benthic Chironominae and Tanypodinae from the Middle Paraná River floodplain habitats (a lake and a secondary channel) were analyzed to determine their feeding patterns and functional feeding groups. Amorphous detritus, animal and vegetal tissues, and mineral materials (predominantly sand) were observed in the larval guts. Amorphous detritus were the main food item found for Polypedilum (Tripodura) sp., Chironomus gr. decorus sp., Endotribelos sp., Phaenopsectra sp., Cladopelma sp., and Pelomus sp. (Chironominae), while animal tissues (mainly oligochaetes) were the most important food item found for Ablabesmyia (Karelia) sp., Coelotanypus sp., and Procladius sp. (Tanypodinae). Dietary overlap was calculated for all pairs of genera. Within predators, the highest overlap was obtained between Coelotanypus sp. and Ablabesmyia (Karelia) sp., while within detritivores the highest niche overlap was obtained between Endotribelos sp. and Phaenopsectra sp.

Larvas de Chironomidae ( Diptera) em depósitos de folhiço submerso em um riacho de primeira ordem da Mata Atlântica (Rio de Janeiro, Brasil)

Neste estudo investigamos a fauna de larvas de Chironomidae presente em depósitos submersos de matéria orgânica (folhiço) em um riacho de primeira ordem na região serrana (cerca de 1100 m) do Estado do Rio de Janeiro. A fauna de Chironomidae do folhiço submerso foi quantitativamente amostrada durante o outono, inverno, primavera e verão. A fragmentação do folhiço foi estimada e a presença de folhas, madeira, raízes e frutos foi investigada. Foram estudadas variações na composição da fauna e na estrutura do folhiço entre as estações do ano e levantadas hipóteses acerca de possíveis fatores que influenciariam os quironomídeos nestes depósitos de folhiço. As subfamílias Chironominae, Orthocladiinae e Tanypodinae foram encontradas e as participações de freqüência de cada subfamília e gênero calculadas em cada estação. Chironominae e Orthocladiinae foram identificados até o nível genérico, e 23 gêneros foram encontrados. Lauterborniella, Polypedilum e Tanytarsus foram os gêneros mais abundantes. Foi observada uma variação na estrutura do folhiço submerso entre as estações do ano, sendo provavelmente influenciada pelas interações entre fatores climáticos (principalmente precipitações) e o relevo e seus efeitos na bacia de drenagem. A fauna de Chironomidae também apresentou mudanças durante o período estudado, com grupos variando quanto à participação relativa e quanto à ocorrência entre as estações. Os efeitos do clima na vegetação e nas características físicas do riacho foram discutidos para elucidar suas influências nos depósitos de folhiço e na fauna de Chironomidae.

Untangling associations between chironomid taxa in Neotropical streams using local and landscape filters

1. Analyses of species association have major implications for selecting indicators for freshwater biomonitoring and conservation, because they allow for the elimination of redundant information and focus on taxa that can be easily handled and identified. These analyses are particularly relevant in the debate about using speciose groups (such as the Chironomidae) as indicators in the tropics, because they require difficult and time-consuming analysis, and their responses to environmental gradients, including anthropogenic stressors, are poorly known. 2. Our objective was to show whether chironomid assemblages in Neotropical streams include clear associations of taxa and, if so, how well these associations could be explained by a set of models containing information from different spatial scales. For this, we formulated a priori models that allowed for the influence of local, landscape and spatial factors on chironomid taxon associations (CTA). These models represented biological hypotheses capable of explaining associations between chironomid taxa. For instance, CTA could be best explained by local variables (e.g. pH, conductivity and water temperature) or by processes acting at wider landscape scales (e.g. percentage of forest cover). 3. Biological data were taken from 61 streams in Southeastern Brazil, 47 of which were in well-preserved regions, and 14 of which drained areas severely affected by anthropogenic activities. We adopted a model selection procedure using Akaike`s information criterion to determine the most parsimonious models for explaining CTA. 4. Applying Kendall`s coefficient of concordance, seven genera (Tanytarsus/Caladomyia, Ablabesmyia, Parametriocnemus, Pentaneura, Nanocladius, Polypedilum and Rheotanytarsus) were identified as associated taxa. The best-supported model explained 42.6% of the total variance in the abundance of associated taxa. This model combined local and landscape environmental filters and spatial variables (which were derived from eigenfunction analysis). However, the model with local filters and spatial variables also had a good chance of being selected as the best model. 5. Standardised partial regression coefficients of local and landscape filters, including spatial variables, derived from model averaging allowed an estimation of which variables were best correlated with the abundance of associated taxa. In general, the abundance of the associated genera tended to be lower in streams characterised by a high percentage of forest cover (landscape scale), lower proportion of muddy substrata and high values of pH and conductivity (local scale). 6. Overall, our main result adds to the increasing number of studies that have indicated the importance of local and landscape variables, as well as the spatial relationships among sampling sites, for explaining aquatic insect community patterns in streams. Furthermore, our findings open new possibilities for the elimination of redundant data in the assessment of anthropogenic impacts on tropical streams.

Chironomidae (Diptera) associado à Eichhornia azurea em seis lagoas marginais ao rio Paranapanema, SP

The family Chironomidae is one of the most important groups within the macroinvertebrate communities, both in density and in richness, and because of its high adaptive value, has a wide distribution on the planet. These and other more specific features of each genus allow the use of this group of biomonitoring studies in the aquatic ecosystem, however, primarily, it is necessary to inventory the aquatic fauna. Thus, this study aimed to evaluate the taxonomic composition of Chironomidae associated with Eichhornia azurea in six lateral lagoons of Paranapanema River, where only five of them have very little information about the aquatic fauna associated with floating macrophytes. Furthermore, we analyzed the influence of environmental conditions on the richness and density of this community. Samples (biotic and abiotic) were held in March and August 2009 on the Ivo, Carmo, Sete Ilhas, Barbosa, Poço da Pedra and Coqueiral lagoons, which are upstream of the Jurumirim Reservoir. Samples with an area of 0.1976 m2 were collected at three banks of E. azurea of each lagoon. Then, they were washed in formaldehyde and water and fixed in 70% alcohol. The identification of morphospecies recorded 38 taxa (32 in March and 37 in August), where the Ivo lagoon is the richest (27 taxa). The density of each group varied according to each pond and is generally Asheum sp., Chironomus sp., Beardius sp., Parachironomus sp., Labrundinia sp., Tanytarsus sp., Ablabesmyia sp. and Polypedilum sp. the most representative. Limnophyes sp., Denopelopia sp., Paratanytarsus sp. and Parametriocnemus sp. were genders in lower density. The Dominance index ranged between 0.1490 (Barbosa Lagoon in March) and 0.4114 (Poço da Pedra Lagoon in March), and the Diversity Index ranged from 2.08 (Coqueiral Lagoon in March) and 3.58 (Barbosa Lagoon in August). The concentration of dissolved oxygen and pH were the environmental variables most correlated with the groups ...