The Balkan Peninsula –one of the world's major hotspots of troglobitic millipedes (Myriapoda: Diplopoda)

Abstract

The Balkan Peninsula is characterized by numerous unique and relict cave animals, both aquatic and terrestrial. This region is known as one of the world's major subterranean biodiversity hotspots. One of the Balkan’s main groups of terrestrial arthropods,rich in troglobites,are millipedes. So far, there are about 150 described troglobitic or presumably troglobitic millipede species and 35genera endemic to this region, altogether represented by approximately50 genera, 13families and fiveorders.Moreover, endemism concerns not only the generic or species level, as there are also three endemic chordeumatidan subfamilies inhabiting the Dinaric region, viz. Acherosomatinae, Biokoviellinae and Macrochaetosomatinae. The largest number of troglobitic species belong to the order Chordeumatida (57 species in 21 genera and six families), followed by Polydesmida (40 species from 13 genera and three families), Julida (30 species, eight genera and one family), Glomerida (16 species, four genera and two families) and Callipodida (one species). Endemic Balkan genera are particularly numerous in the order Chordeumatida, with 18 genera, while Polydesmida, Julida, Glomerida and Callipodida are far less diverse, with nine, six, one and one endemic genus, respectively. Such an extraordinary rich fauna of subterranean millipedes,as presently estimated in the Balkan Peninsula,is far from completely known. During the last decade alone,a large number of new taxa have been described. The complex and long geological history, coupled with palaeoclimatic changes, resulted in a great subterranean biodiversity in the Balkans, a region which indeed merits the term of one of the main biodiversity hotspots of endogean fauna globally.