Algal and fungal symbionts of the lichenized genus Thamnolia typically co-disperse through thallus fragmentation, which may be expected to lead to fungal associations with a restricted range of algal symbionts. Here we examine the range of algae that associate with the fungus Thamnolia vermicularis. Phylogenetic analyses of internal transcribed spacer rDNA (ITS) sequences suggest that Trebouxia algae associated with T. vermicularis are not monophyletic. Algal and fungal phylogenies were compared, and although some congruence was found, a Mantel test found no significant correlation between fungal and algal genetic distances. An AMOVA suggested that ecogeographic factors play a stronger role than fungal genotype in structuring photobiont diversity. Additionally, as a species, T. vermicularis associates with a range of algae equal to or greater than that of many other fungal taxa.