Composição e estrutura da acarofauna (acari: mesostigmata; trombidiformes; endeostigmata) em ambientes edáficos na Mata Atlântica no sul do Brasil

Abstract

The aim of this study was to understand the composition and diversity of soil mite fauna related to the Atlantic Forest biome in Rio Grande do Sul, in two different forest types: Atlantic Araucaria forest (AAF) and Atlantic rainforest (ARF). Species richness, abundance and similarity of the soil mite fauna were compared, assessing whether spatial factor (dispersion limit), as well as biotic and abiotic environmental factors influence the community of edaphic mites in Southern Atlantic Forest. For each forest type, were chosen ten sampling sites. To assess the diversity of soil mite fauna in each sampling point, six sub-samples were collected for both the soil microenvironment as to litter microenvironment thereby guarantee adequate sampling effort within each sample point to estimate the diversity and composition mite species. To determine the influence of stochastic processes (dispersion limit) and deterministic (abiotic and biotic factors) in the community of edaphic mites we create two matrices, the first including the geographical distance. The distance between sampling sites was used as a predictor to study the role of dispersion limits in the formation of community. To estimate the potential of deterministic processes which can structure the community of mites, we create another matrix with the abiotic and biotic factors, including the particle size, moisture organic matter of soil , density structure of vegetation, depth and percentage of leaves, branches and fine root of litter and oribatid density were measured. In total have been collected 3081 mites, being 2091 adults and identified in 130 species / morphospecies with 25 singletons and 15 doubletons. The genus Pyrosejus, Polyaspis, Clausiadinychus, Multidendrolaelaps, Athiasella, Veigaia, Holostaspella, Gaeolaelaps, Gymnolaelaps, Labidostoma, Rhagidia, Stereotydeus, Laminochaelia are registered for the first time for the Rio Grande do Sul State and the species Neocunaxoides promatae Rocha, Rodrigues and Ferla, 2015, Bonzia flechtmanni Rocha, Rodrigues and Ferla, 2015 and Dactyloscirus multiscutus Rocha, Rodrigues and Ferla, 2015 were described and illustrated in this study. Total abundance, abundance of adult mites and species richness showed higher values in ARF, which totaled 111 species, while in AAF was observed 90 species. When microenvironments were compared separately, it found that the litter had a higher abundance and species richness. The oribatid density had a significant influence on the abundance and richness of mite fauna. The composition between forest types did not differ, however, it was observed that the mite communities in the closest sampling sites, regardless of forest type were more similar to each other than those far away. The depth of the litter, the particle size, percentage of organic matter in the soil and oribatid density were evaluated factors that have contributed substantially to the variation of the mite fauna community. These results provide strong evidence of the limits of dispersion and biotic and abiotic factors are important drives to the edaphic mite compostion in the Atlantic Forest in southern Brazil. Thus, we can conclude with this study that these environments require urgent attentionbeing priority areas for the conservation of biological diversity, because of its importance to adjacent ecosystems.