Small habitats as a source of hidden biodiversity on the example of genus Eumerus Meigen, 1822 (Diptera: Syrphidae)

Eumerus Meigen (Diptera: Syrphidae) as one of the most speciose hoverfly genera in Europe is found to be a significant part of hoverfly fauna on Durmitor mountain (Montenegro). We found that majority of species registered on this mountain is concentrated in small species-rich habitat patches. One of these localities, Komarnica - Pošćensko Lake, stands out as particularly rich, comprising 9 out of 14 recorded Eumerus species on Durmitor mountain (E. amoenus Loew, 1848, E. consimilis Šimić & Vujić, 1996 and E. montanum rković, adenković & Vujić, 2017 from strigatus group, E. argyropus Loew, 1848 from ornatus group, E. montenegrinus, rković & Vujić in litt, and E. sulcitibius Rondani, 1868 from barbarus group, E. grandis Meigen, 1822 and E. nigrorufus, rković & Vujić, in litt, from tricolor group and E. hungaricus zilády, 1940, which has not been assigned to any group yet). This locality also represents the type locality for recently described Eumerus montanum Grković, Radenković et Vujić, 2017 and two undescribed new species (E. montenegrinus, in litt. and E. nigrorufus, in litt). Eumerus montenegrinus, in litt. belongs to barbarus group which in addition consists of four other Mediterranean species. This species, possibly very vulnerable because of its restricted range, is recorded with one single male specimen, despite of regular sampling. Eumerus nigrorufus, in litt. is a representative of tricolor group, the largest European Eumerus species group and besides being found on Durmitor mountain, it is recorded on two other localities in Greece (Corfu, Peloponnese). 72 Although the Durmitor mountain is protected as National Park and the UNESCO World Heritage Site, we consider it is essential not to change the type of land use of small and particularly important ecosystems in order to preserve its fragile diversity.