Distribution, ecology and conservation status of two endemic amphipods, Echinogammarus acarinatus and Fontogammarus dalmatinus, from the Dinaric karst rivers, Balkan Peninsula

The Balkan Peninsula is recognized to be one of the most important biodiversity hotspots worldwide. However, biogeographic patterns of its freshwater fauna are poorly understood due to the lack of basic data on distribution and ecology, particularly for endemic taxa. We studied the distribution, habitats and conservation status of two endemics, Echinogammarus acarinatus and Fontogammarus dalmatinus , in the Dinaric karst rivers. Altogether, 711 sites were sampled from 2000 to 2014 and supplemented by literature data. Although previously known only from rivers of the Adriatic Sea (AS) basin, both species were also found in the Black Sea (BS) basin. E. acarinatus has a mosaic distribution extending from the Una River to the delta of the Neretva River, particularly in the rivers Vrbas and Bosna (BS). Its presence in the AS basin rivers, Krka and Neretva, could result from river capture events by which former tributaries of the Una and Bosna (BS) were directed to the AS basin. Two subspecies of F. dalmatinus are distributed in the Una, Zrmanja and Krka Rivers. F. dalmatinus dalmatinus occurs in upper and middle parts of the Zrmanja (AS), and in the upper part of the Una (BS), while F. dalmatinus krkensis was found exclusively in springs and upper parts of the Krka (AS). Distribution of both subspecies in the Zrmanja and Krka indicates former connection between these rivers. The ecology and conservation status of all the studied taxa are presented and discussed. This study illustrates the importance of including ecological and historical interpretations of species’ distributions for managing conservational issues in the case of freshwater endemics with narrow ranges.