The mechanisms which structure communities have been the focus of a large body of research. Here, we address the question if habitat characteristics describing habitat quality may drive changes in community composition and beta diversity of bromeliad-inhabiting microfauna. In our system, changes in canopy cover along an environmental gradient may affect resource availability, disturbance in form of daily water temperature fluctuations and predation, and thus may lead to changes in community structure of bromeliad microfauna through differences in habitat quality along this gradient. Indeed, we observed distinct changes in microfauna community composition along the environmental gradient explained by changes in the extent of daily water temperature fluctuations. We found beta diversity to be higher under low habitat quality (low canopy cover) than under high habitat quality (high canopy cover), which could potentially be explained by a higher relative importance of stochastic processes under low habitat quality. We also partitioned beta diversity into turnover and nestedness components and we found a nested pattern of beta diversity along the environmental gradient, with communities from the lower-quality habitat being nested subsets of communities from the higher-quality habitat. However, this pattern resulted from an increase in microfauna alpha diversity with an increase in habitat quality. By providing insights into microfauna-environment relationships our results contribute to the mechanistic understanding of community dynamics in small freshwater bodies. Here, we highlight the importance of habitat characteristics representing habitat quality in structuring communities, and suggest that this information may help to improve conservation practices of small freshwater ecosystems.

We characterized and compared taxonomic features of two species of tree crickets Oecanthus in tobacco plantation and adja-cent native trees and bushes at Southern Brazil. The marked differences between species included Oecanthus n. sp. with pale-green body, pale-yellow head, greenish-white eyes, file teeth number 32.8±1.2 (31–34, n = 6) and hindwings caudate. Oecan-thus lineolatus is slightly darker as pale-green, with pale-green head, yellow eyes, hind femur variegated with translucent andpale-green, file teeth number 47±2.2 (42–51, n = 18) and hindwings non caudate. Both species also differ in calling song dominant frequency and temporal parameters, as well as in the morphology of metanotal gland.

ABSTRACT

We provide herein a description of a new species of Oecanthus collected from the tobacco plantation in southern Brazil, municipality of São Lourenço do Sul, State of Rio Grande do Sul. Description focused metanotal gland features, phallic sclerites, and calling song. A large sampling of individuals was distributed into four groups according to body and appendages color and dotted. We also rank all kind of marks present in the scape and pedicel. We compare linear morphometric variables of the metanotal glands and tegmina, as well as calling song parameters between groups in order do define all of them as the same species. Photographs and measurements are provided.

No abstract