Estrutura da comunidade de Chironomidae na Reserva Florestal Adolpho Ducke, Amazônia Central, e associação de larvas e adultos de gênero Polypedilum Kieffer (Diptera: Nematocera)

Abstract

The purpose of this study was to describe the spatial and temporal distribution of the Chironomidae assemblage and relate these distributions to environmental factors. The study also establishes the association between the larvae and adults of some species/morphotypes in the genus Polipedilum Kieffer. A total of 11,650 Chironomidae larvae were identified; these were collected in riffle and pool habitats at 38 sampled points in two hydrographic basins at the Reserva Florestal Adolpho Ducke in the rainy and dry seasons in 2004. The most abundant genus was Polipedilum (16%) in both sampled periods. The Chironomidae assemblage was more abundant in the rainy season (P< 0,05), but its composition and richness were relatively stable (P< 0,05).. No differences in abundance and composition were found based on hydrographic basins, riffle and pool habitats and the gradient of stream sizes. The abundance in riffles and pool habitats was different when the Chironomidae genus had been analyzed separately. Canonical correspondence analysis was used to describe the distribution pattern (composition) of Chironomidae genera as related to abiotic factors; the analysis showed a distinct seasonal pattern in the structure of the community. Fourteen morphotypes of Polipedilum were found, among which four associations of larvae and adults were obtained from rearing in the laboratory. Two larvae were associated with the already-described species Polypedilum falax Johannsen and Polypedilum tupi Bidawid & Kafka, and another two species could not be associated with any species that occurs in the Amazon forest. An identification key for species/ morphotypes of Polypedilum larvae in the Reserva Florestal Adolpho Ducke is presented.