Project aims to explore diversity and biogeography of the species from the diatom genus Frustulia. Species identification and delimitation uses integrative taxonomical approach, which combines molecular data, traditional and geometric morphometrics, and ecology inferred from in situ measurement of environmental variables (pH, conductivity) and experimental cultivation under controlled conditions. A number of freshwater habitats worldwide (Europe, New Zealand, Patagonia, Canada, etc.) have been sampled to date; preliminary results as well as several recent publications show that diversity of diatom species correlates with the density of freshwater bodies in the area. Therefore, the amount of potentially suitable habitats in northern Michigan makes us to target our next sampling in this area.