To contribute to the knowledge on the composition and distribution of the butterfly fauna of the Southeastern region of Rio Grande do Sul state (RS), five areas at Serra do Sudeste were sampled between April/2003 and January/2004. The species composition of Nymphalidae, Papilionidae and Pieridae was compared with existing records for the contiguous areas at the foot of Serra do Sudeste and the South Coast Plain (Pelotas and surroundings). In a total of 289 net-hours of sampling at Serra do Sudeste, 2.326 individuals in 81 species were recorded: 59 Nymphalidae, 12 Papilionidae and 10 Pieridae. Literature data available for the adjacent areas lists 138 species. Putting both sources together, a total of 152 species are now registered for the Southeast Region of RS: 110 Nymphalidae, 14 Papilionidae and 28 Pieridae. Amongst these species, 14 (9%) occur only in Serra do Sudeste, and 71 (47%) only at the contiguous areas. The results demonstrate the peculiar composition of Serra do Sudeste lepidopterofauna and emphasize the biological importance of this area of Rio Grande do Sul.
butterflies; species richness; conservation
