Lichens redefined as complex ecosystems

Abstract

This article is a Commentary on Mark et al. (2020), 227: 1362–1375.

Keywords: endolichenic fungi; galls; holobiont; lichen-associated bacteria; lichenicolous fungi; mycobiont; photobiont; symbiosis; yeasts.

Fig. 1

Gall‐forming lichenicolous fungi. (a) Convex galls (arrowheads) formed by the basidiomycete fungus Tremella cetrariicola on the lichenized Tuckermannopsis chlorophylla (photo: M. Grube). (b) Bullate galls (arrowheads) formed by the ascomycete fungus Telogalla olivieri on the lichenized Xanthoria parietina; the black spots on the galls are the openings of the spore‐producing structures of the Telogalla (photo: D. L. Hawksworth). The Tremella hypertrophises only the main fungal partner turning into a spore‐forming body, while the Telogalla hypertrophises the lichen structure and includes both the lichen‐forming fungus and its associated algae, and the yellow‐orange anthraquinone parietin continues to be produced. The letter a indicates the spore‐producing structures of the main lichen fungus. Bars, 1 mm.