Aquatic insects are widely used as indicator taxa to assess the ecological state of streams and to evaluate the success of stream restoration projects. Information on intraspecific genetic diversity and population connectivity is often lacking for such indicator taxa. However, these parameters are of critical importance for restoration plans and conservation management because: 1) species sometimes consist of several cryptic species and 2) species can recolonize only those restored habitats within a reachable distance from their source populations. Gene flow generally cannot be observed directly, and molecular markers provide a reasonable alternative to assess the dispersal potential and evaluate species' genetic diversity. We investigated the genetic diversity and dispersal potential of the predatory stonefly Dinocras cephalotes using 323 specimens from 29 populations in the Sauerland, a low mountain range in Germany. We used a 658 base pair (bp) fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) and found 2 distinct and diverse haplotype groups, which were shared across most populations. The groups were separated by a minimum intraspecific P-distance of 4.3%, suggesting historic isolation and possible presence of cryptic species. However, complementing analyses of the nuclear Wingless gene and 3 newly developed microsatellite markers clearly showed that individuals from both COI haplotype groups are interbreeding, and therefore, D. cephalotes is considered a single valid species. Population comparisons indicated high connectivity among all populations, with only a few individual populations showing signatures of isolation. Based on the molecular data, we conclude that dispersal is primarily achieved by the adult females of D. cephalotes.