| Abstract: | The rithral and hypocrenal (of small rapid streams) macrobenthos faunas of northern Greece, eastern Carpathians, montane Crimea, and northwestern Caucasus are comparatively analyzed based on original material. Peculiarities of the rheophile communities and faunas of each region and of the whole studied area are described. The area is provisionally divided into biogeographic unites based on rithral fauna; this classification is essentially different from those of other authors. The main faunistic border runs meridionally between Greece-Carpathians on one side and Caucasus-Crimea on the other. The present authors believe that the biogeographic variability of macrobenthos rithral faunas results from the position of regions containing rithron communities and from spatial ties between them. Three fundamental biogeographic zones, suggested to be ranked as subregions, are recognized in the West Palearctic: the Balkan-Alpine (West European), the Scandinavian-Ural (North European), and the Caucasian. All the data available fit the suggested scheme, which shows that this approach is of universal value to biogeographic analysis and to divisions of the rithral into biogeographic zones. The local-scale variability of rheophile macrobenthos fauna in the northwestern Caucasus is discussed. Significant faunistic similarity of territories comprising the studied area is shown, internal division into biogeographic zones is conducted, and the lowest scale border of the faunistic diversity of rheophile macrobenthos is established at about 100-150 km. |
