RESUMO
This study highlights the species diversity of Ceratopogonidae from the Paranaense forest and adjacent grassland in a protected natural area of Argentina, and emphasizes the importance of conserving the last remaining marginal forest area surrounded by a strong urbanization. A total 46 species belonging to 10 genera were recorded from these two habitats. Species diversity was higher in the grassland, while dominance was greater in the forest. Twelve species were abundant, while the rest were scarce or rare. The composition of the ceratopogonid community differs between habitats: 15 species were exclusive to the forest, 4 to the grasslands, and 27 used both habitats indistinctly. Differences between habitats were observed in the abundances of Alluaudomyia schnacki Spinelli, Atrichopogon albinensis Ingram and Macfie, and Forcipomyia rioplatensis Marino and Spinelli. The sex ratio of the most abundant species did not show a definite pattern in relation to the habitats, except for Culicoides caridei (Brèthes), in which females were dominant. Atrichopogon balseiroi Spinelli and Forcipomyia williamsi Marino & Spinelli have only been recorded in Buenos Aires Province and were found exclusively in the forest during this study.