Diversity of Trichoptera (Insecta) in protected and unprotected areas of the Argentinian Parana and Araucaria Forest provinces

Northeastern Argentina is covered by a subtropical forest that extends through the Parana and the Araucaria Forest provinces. It is considered a biodiversity hotspot, and it has been studied extensively in regard to the diversity of vertebrates and vascular plants, but the knowledge of invertebrates, in particular insects, is scarce. In order to address this gap, the diversity of caddisfly species, a group of aquatic insects inhabiting freshwater systems and its riparian habitat, was analyzed. Specimens of Trichoptera from insect collections and bibliographical data were used to estimate the species richness and composition of the two biogeographical provinces, its protected and unprotected areas, and the Yungas province, the other main area of diversification of Trichoptera species in Neotropical Argentina. Additionally, two indexes that incorporate the taxonomic structure of each area were calculated to estimate its diversity: the average taxonomic distinctness and its variation. The study showed that both biogeographical provinces harbor 43.3% of the Trichoptera species of the country, even though an extensive understudied area in the Uruguay River basin was found. Twenty four new records were provided, 15 for Argentina, and 27 endemic species identified. Despite finding differences in species composition, species richness and sometimes the taxonomic structure of the assemblages, the diversity of the studied areas resulted similar, only being lower in the Yungas province. Our results show a complementarity of the species composition in the different areas, highlighting the importance of the preservation of each one to maintain the pool of species of the region.