The Atlantic Forest is the biome with the largest biodiversity and endemism rate of anuran amphibians in the world. However, information on natural history and patterns of occurrence are still unknown for most of the species that occur in this biome. In this study the diversity and the seasonal occurrence of anuran amphibians were determined in an ecotone area between Atlantic Forest and Araucaria Forest, in the southeastern of Paraná state. In the survey, accomplished from January 2003 to May 2004, 34 species from five families were registered: Bufonidae (two species), Hylidae (17 species), Leptodactylidae (13 species), Microhylidae (one species) and Ranidae (one species). The species richness is one of the largest of Paraná state and eight of the nine studied sites presented high diversity of species. The fact that the studied area is located in an ecotone supports the occurrence of typical species from two physiognomies. Besides, an additional hypothesis to explain this great diversity is the intermediate disturbance due to the deforestation that occurred until thirty years ago, which made the occurrence of some typical species from open areas possible. The largest number of species (48%) occurred during the rainy season, however, the proportion of annual species was great (25%), similar to the one found in regions with wet tropical climate (30%). The similarity in species composition among nine localities in Atlantic Forest in Paraná State was associated to the vegetal physiognomy of the studied areas.
Atlantic Rainforest; community ecology; species richness
