From the point of view of biogeographers and ecologists, taxonomy is not only a means of ordering life but also a source of some problems able to impede the progress in studies of large-scale patterns of biological diversity. Discrepancies among systematists caused, inter alia, by their different views on the species concept and criteria for species delineation, are commonly thought to provoke errors and misinterpretations in macroecological inferences. In this study, we discuss a case of freshwater gastropods of Western Siberia. Two systematic frameworks, developed in Western Europe and Russia and drastically different in number of accepted genera and species, were proposed to classify the Palearctic aquatic snails. Having compared two sets of diversity data generated on the basis of the two systematic frameworks, we found that their parameters do not differ significantly. Such patterns as latitudinal gradients in total species richness, portion of branchiate snail species, and portion of species of non-European origin proved to remain the same, irrespective of which taxonomic approach, Western European, or Russian, is accepted. The absence of reliable changes in macroecological patterns may be explained by nearly consistent “splitting effort” applied by the Russian taxonomists in their revision of different families of aquatic snails. Thus, though the European and the Russian systematic frameworks differ significantly in number of accepted species, the large-scale patterns of diversity based on the two approaches are qualitatively the same.