Spiders (Araneae) from the high altitude zone of Rila Mountain (Bulgaria)

82 species (1 Segestriidae, 1 Zodariidae, 1 Metidae, 5 Araneidae, 29 Linyphiidae, 7 Theridiidae, 14 Lycosidae, 5 Agelenidae, 6 Clubionidae, 4 Gnaphosidae, 4 Philodromidae, 2 Thomisidae, 3 Salticidae) are established from 24 sites (2000-2925 m) in the high attitude zone of Rila. The species composition of the high mountain spider community was not well known and this is the first contribution to the problem. Concerning the altitudinal distribution, there are only 11 species occurring mainly in the alpine belt, though a good number of species is present in the subalpine belt also and even some in the lowlands. Characteristic for the highest points are Araeoncus clivifrons, Erigone pirini, Metopobactrus orbelicus, Scotinotylus alpigenus, Tiso aestivus, Lepthyphantes annulatus (Carpatho-Balkan relict), L. improbulus, L. lithoclasicolus, Oreonetides glacialis, Pardosa nigra, Gnaphosa muscorum. The species (20) which are not found below the tree-line can be regarded as high mountain species complex, which is composed by euro-mountaine (7, 35%), endemic (6, 30%), holarctic (2, 10%), palearctic (1, 5 %), arctic-alpine (2, 10%), and mountaine-mediterranean (1, 5%) elements. The high percentage of endemics shows that the process of autogenesis is considerable but the process of colonization, mainly by Middle-european species is stronger.