The Teloschistaceae is generally recognized as a rather natural unit in the lichenized Ascomycotina. However, the same family has long been known to include an assemblage of rather unnatural genera and, in addition, there are numerous problems concerning delimitation of species among those genera. Problems related particularly to gradual geographical speciation are discussed in three of the most important genera in the Teloschistaceae and illustrated mainly from the African flora in the genera Xanthoria, Teloschistes, and Caloplaca. In one species in particular, Xanthoria mendozae, the known distributional pattern in the Southern Hemisphere supported by geological events and with only few opportunities for long-distance dispersal, indicates an ancient history for this lichen. Two cladograms or strict consensus trees are presented, supporting the presumed unnatural affinities among accepted genera in the family