Convergent evolution underground - two new troglomorphic collembolan species of the genus Schaefferia Absolon, 1900 (Collembola, Poduromorpha, Hypogastruridae) from Iran and Montenegro

Two new subterranean springtail species of the genus Schaefferia Absolon, 1900 are described: S. greensladeae sp. nov. from Danial Cave in the Alborz Mountains, Iran, and S. montenegrina sp. nov. from Babatuša Cave in Dinaric Karst, Montenegro. Both species are characterized by the absence of eyes and postantennal organ (PAO) having more than 5 lobes in the contrary to other eyeless congeners that have less than 5 lobes in PAO. Morphological traits of both species indicate high level of association with the subterranean environment. The phylogenetic relationships and morphological adaptations of two new species to subterranean life are discussed. Schaefferia greensladeae sp. nov. and S. montenegrina sp. nov. serve as a good example of convergent evolution that is characteristic of invertebrates highly adapted to deep subterranean realm. An updated key to the world species of the genus and a table summarizing diagnostic characters of the world species of Schaefferia are provided.