The Balkan Peninsula (also known as The Balkans) is a geographic area in Southeast Europe. The region takes its name from the Balkan Mountain that stretches from East Serbia through the whole Bulgaria, to the Black Sea. The Balkan Peninsula is bordered by the Adriatic Sea in the northwest, the Ionian Sea in the southwest, the Aegean Sea in the south and the Black Sea in the east. The northern border of the peninsula is variously defined. Some authors accept it to be the Danube river, others think that it is a Carpathian Arc, which means that the North Dobrodgea is a part of the Balkans as well. Although not geographically correct, here, for faunistic purposes, we decided to include in the region the whole Romania. The highest point of the Balkans is Musala Peak (2925 metres) in Rila Mountain, Bulgaria.

The unique fauna of the Balkan Peninsula is characterized with high percentage of endemic species, especially in the Greek islands, the Dinarides and the Bulgarian Mountains. The region is also a major glacial refuge and a crossroad for different faunistic elements, facilitating their spreading towards the Europe. Together with the territories surrounding the Black Sea Basin, the Balkan Peninsula bridges the two well recognized biodiversity hotspots – the Mediterranean Basin and the Caucasus. The biodiversity of the region is characterized not only by an extremely rich number of unique species but also by a large diversity of distribution patterns. The high percentage of endemism in the most biodiverse areas of the region and the affinities of these endemics to Central European species illustrate both the key role of the Balkans in generating local diversity and its role as a cradle of significant part of the present-day European diversity.

Spiders are among the most abundant and ubiquitous predators in terrestrial ecosystems in the region and play a pivotal role in regulating trophic networks, consuming millions of tons of insects a year and providing essential amino acids as food source for birds and other vertebrates. Spiders are also providers of ecosystem services to human societies, by controlling populations of pest and vectors and producing natural products of medical and engineering relevance (e.g. venoms and silk). Spiders are highly diverse and their diversity is relatively well characterized and understood, providing an excellent model for biodiversity studies. Additionally, as predators, spiders are especially sensitive to environmental perturbations, constituting an excellent bioindicator for conservation assessment. Because of the unique environmental conditions in the region and the restricted distribution, the local endemic fauna is most sensitive to environmental changes and therefore of high conservation concern.

The first publication summarizing the data of the spider fauna, known at that point in time is Pencho Drensky’s “Katalog der echten Spinnen (Araneae) der Balkanhalbinsel”, issued in 1936. Since then, the spiders of the Balkan Peninsula have been studied by different arachnologists as Paolo M. Brignoli, Jan Buchar, Christa L. Deeleman-Reinhold, Christo Deltshev, Josef Kratochvíl, František Miller, Konrad Thaler, Jörg Wunderlich, and many others.

Although today in arachnology we have two great scientific resources – the World Spider Catalog and Araneae, there is no faunistic database tracking all the records of the species with the precise information about their localities. With an intention to fill in that gap, we started the “Balkan Spiders” platform. It is planned to be an online catalog, summarizing all the faunistic data about the spider fauna of the Balkan Peninsula and providing original images of the species from the region.