A new giant keelback slug of the genus from the Balkans, described by citizen scientists.

Background: Despite their large size, striking colouration and genital extravagance, the taxonomy of the European giant keelback slugs of the genus is still poorly understood. Preliminary morphological and molecular data suggest that many unnamed or unrecognised species exist, especially in the Alps, the Mediterranean and the Balkans.

New Information: We organised a citizen science expedition to Durmitor National Park in Montenegro and discovered a new species, genetically distinct, but morphologically similar to the sympatric Wolf 1803 and describe it as .

(s.str.) , new species (Coleoptera: Hydraenidae) along with further records of spp. from Durmitor National Park, Montenegro and comments on the DNA barcoding problem with the genus.

Background: 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-based pipeline.