Long-palped Water Beetles were collected during a taxon expedition in Montenegro which involved citizen scientists, students and taxonomists. The material was collected from springs, brooks, fens and the Tara River, at altitudes between 600 m and 1450 m above sea level, using fine-meshed hand-nets and by manual checking of submerged substrates. The morphological species delimitation was supplemented and congruent with mtDNA sequences mainly obtained in the field using the newly-developed MinION-basedONTrackpipeline.The new speciesHydraena dinaricaFreitag & de Vries, sp. n. from Durmitor Mt. is described, illustrated and compared in detail to closely-related congeners of theH. sagad'Orchymont, 1930/H. emarginataRey, 1885 species complex. Five additional species and female specimens of two unidentified morphospecies of the genus were also recorded in the vicinity of Durmitor National Park. New records and the first DNA barcodes forHydraena biltoniJäch & Díaz, 2012 (endemic to Montenegro) andH. morioKiesenwetter, 1849 are provided. Further records ofH. nigritaGermar, 1824,H. minutissimaStephens, 1829,H. subintegraGanglbauer, 1901 and females of two unidentified morphospecies are commented upon. The resulting inter- and intraspecific genetic distances and some observations of low or zero sequence divergence between recently-diverged species ofHydraenaKugelann, 1794 are briefly discussed.