Myrmecofauna of ironstone outcrops: composition and diversity

The Iron Quadrangle in the state of Minas Gerais, Brazil, harbors ironstone outcrops locally known as cangas, which are historically under great anthropic pressure. The functions performed by ants in environments with severe edapho-climatic conditions, such as cangas, are poorly known. Considering the lack of studies and the potential role of ants in cangas, this study aimed to identify the taxonomic composition of the myrmecofauna that occurs in the soil of two campo rupestre areas (rupestral plant communities) on cangas under different anthropic impacts and evaluate the influence of seasonality and degree of degradation on the diversity and composition of the myrmecofauna. This is the first study to systematically investigate ant fauna collected with baits on ironstone outcrops. Sardine and honey baits were used in dry and rainy periods. Fourteen species distributed among ten genera belonging to five subfamilies were found. The total number of baits visited in the dry season was lower than in the rainy season. Both habitats had a reasonable similarity in their composition (Jaccard similarity index = 0.571). Multivariate analyses suggest a greater similarity between areas than seasons. The diversity of ants in the cangas is low compared to other Cerrado environments where more than 20 species are frequently collected in these types of study. This low richness may be related to the adverse conditions characteristic of ironstone outcrops. We hope our data will help to expand the actions to manage and preserve cangas in the Iron Quadrangle.