Plectocarpon

Plectocarpon is a genus of lichenicolous (lichen-dwelling) fungi in the family Lecanographaceae. The genus, which was established in 1825 by the French botanist Antoine Laurent Apollinaire Fée, contains about 30 species that live as parasites on other lichens rather than forming their own independent body (thallus). These fungi are recognized by the small, wart-like swellings they create on their host lichens and by their distinctive dark fruiting bodies that often contain a green pigment that dissolves when treated with potassium hydroxide solution.

Taxonomy

The genus Plectocarpon was established by the French botanist Antoine Laurent Apollinaire Fée in 1825, and later formally circumscribed in his 1837 work Essai sur les cryptogames des écorces exotiques officinales ("Essay on the cryptogams of exotic officinal barks"). In his protologue, Fée explained that he was creating a new genus separate from the existing genus Delisea, noting that while the two genera shared some similarities, they differed significantly in important characteristics. Fée emphasized that Plectocarpon was distinguished by its unique reproductive structures, particularly the nature of its spore-bearing organs and their development. He described how the genus differed from related groups like the genera Opegrapha and Arthonia in the structure of its fruiting bodies and the way they formed on the host lichen surface. The French botanist noted that these parasitic fungi created distinctive swellings or modifications in their host lichens, which became a key identifying feature of the genus.

Description

Plectocarpon species do not make a lichen body (thallus) of their own; instead they live on the thalli of other lichens. The parasite's presence is usually revealed by small, wart-like swellings (galls) that rise from the host surface, but these growths rarely harm the host beyond local distortion.