Are latitudinal richness gradients in European freshwater species only structured according to dispersal and time?

The latitudinal gradient in species richness of the European freshwater fauna is usually depicted as a contrasting pattern between lentic (standing waters) and lotic (running waters) habitats. Species richness decreases from south to north in lotic habitats, while lentic habitats show an intermediate richness peak in central Europe (Hof et al. 2008). In this Brevia we question the strict dichotomic split in latitudinal richness patterns between lentic and lotic habitats in Europe. We do this by demonstrating that the differences in richness patterns between headwater streams and rivers are as great as the differences between lentic and lotic habitats. We also show that species richness can be explained solely by the hypervolume defined by the variety of lotic habitats preferences in a region.