Hadesia is a charismatic and scientifically important genus of cave beetles. It is a classical representative of the subterranean fauna of the Dinaric Karst and the model upon which the ultra-specialized ecomorphological form of semi-aquatic, hygropetricolous filter feeders became known. We describe a new species, Hadesia zetae sp.n., from southwestern Montenegro, and employ new morphological characters to build an identification key to all five species of the genus. Based on DNA sequence data from two nuclear and two mitochondrial genes and using multispecies coalescent methods, we corroborated their reciprocal monophyly and inferred a well-supported phylogenetic hypothesis. Molecular dating suggests that the most recent common ancestor of the extant Hadesia species lived about three million years ago, during the warm and wet mid-Pliocene, and diversified allopatrically through range fragmentation caused by habitat reduction during the Pleistocene. Because of their extreme rarity and observed negative impact of collection pressure, we discourage collecting of Hadesia at known sites.

Leptodirini, Anthroherponina, Hadesia, new species, molecular phylogeny, Dinaric Karst, troglobiont, subterranean, cave hygropetric.