In spite of harboring high richness of anuran amphibians, Brazil still has many regions considered to be undersampled, including ecosystems which are degraded and threatened. This is the case of the Mixed Ombrophile Forest (FOM), a formation which has only 3% of its original vegetation, and an even smaller percentage of it constitutes forests in primary or advanced stages. The objective of the present study was to determine the structure of an assemblage of anurans in a remnant of the Mixed Ombrophile Forest, comparing that assemblage with 8 other assemblages known to occur in localities in the Mixed Ombrophile Forest formation, and to verify if the richness of each local varies according to the quantity or types of sites sampled in each inventory. A total of twelve campaigns were carried out from September 2008 to August 2009 to sample 11sites, totaling 72 sampling hours. Through the methods of sampling at breeding sites in seven sites and aural search in four transects, the occurrence of 24 species from seven families was registered, corresponding to 96% of the estimated richness in the area (n=25). Both richness and specific abundance were registered in the wettest period. The number of species in the sites varied from one to 15, and almost half (41%) of them were exclusive of forest environment. The most important variable for the register of a higher number of species in the present study and other areas inside FOM was the quantity of types of sampled sites, and not the area size and total number of habitats, indicating that sampling in heterogeneous environments, which may harbor more reproductive modes for anurans, enhance local richness registers. Despite being a small and altered fragment, the observed richness was high if compared to other areas whose anurofauna was inventoried inside the araucaria forest domain, with a similar sampling effort. Due to occurrence of many species dependent on the integrity of the forest, the minimization of anthropic activities and more detailed studies must be the main goals for their maintenance and local conservation.
Amphibians; anurofauna; araucaria forest; environmental heterogeneity; inventory
