Data from: Basidiomycete yeasts in the cortex of ascomycete macrolichens

For over 140 years, lichens have been regarded as a symbiosis between a
single fungus, usually an ascomycete, and a photosynthesizing partner.
Other fungi have long been known to occur as occasional parasites or
endophytes, but the one lichen–one fungus paradigm has seldom been
questioned. Here we show that many common lichens are composed of the
known ascomycete, the photosynthesizing partner, and, unexpectedly,
specific basidiomycete yeasts. These yeasts are embedded in the cortex,
and their abundance correlates with previously unexplained variations in
phenotype. Basidiomycete lineages maintain close associations with
specific lichen species over large geographical distances and have been
found on six continents. The structurally important lichen cortex, long
treated as a zone of differentiated ascomycete cells, appears to
consistently contain two unrelated fungi.