The green algal photobionts of 12 Xanthoria, seven Xanthomendoza, two Teloschistes species and Josefpoeltia parva (all Teloschistaceae) were analyzed. Xanthoria parietina was sampled on four continents. More than 300 photobiont isolates were brought into sterile culture. The nuclear ribosomal internal transcribed spacer region (nrITS; 101 sequences) and the large subunit of the RuBiSco gene (rbcL; 54 sequences) of either whole lichen DNA or photobiont isolates were phylogenetically analyzed. ITS and rbcL phylogenies were congruent, although some subclades had low bootstrap support. Trebouxia arboricola, T. decolorans and closely related, unnamed Trebouxia species, all belonging to clade A, were found as photobionts of Xanthoria species. Xanthomendoza species associated with either T. decolorans (clade A), T. impressa, T. gelatinosa (clade I) or with an unnamed Trebouxia species. Trebouxia gelatinosa genotypes (clade I) were the photobionts of Teloschistes chrysophthalmus, T. hosseusianus and Josefpoeltia parva. Only weak correlations between distribution patterns of algal genotypes and environmental conditions or geographical location were observed.