“…Some black fly species may occur only in the riffles of large rivers, while others are restricted to small streams of slower water currents (Bertazo and Figueiró, 2012;Figueiró et al, 2006Figueiró et al, , 2008Figueiró et al, , 2014Hamada et al, 2002;Shelley et al, 2000;Zhang and Malmqvist, 1996). Ecological theory and some empirical studies suggest that the habitat choice may be directly influenced by labral fan morphology (Carlsson, 1962;Grenier, 1949;Kurtak, 1978;Lewis, 1953), with black fly species from faster water velocities tending to have smaller labral fans, with stout rays, while species that occur in slower water current velocities tend to have longer labral fans and more delicate rays (Malmqvist et al, 1999;Palmer and Craig, 2000;Zhang and Malmqvist, 1996).…”