poraenia

Poraenia is a genus of lichenicolous fungi belonging to the family Stictidaceae within the order Ostropales. The genus was first described by Swedish lichenologist Erik Acharius in 1808 and has since been recorded primarily in temperate regions of Europe and North America. Species within Poraenia are specialized parasites that infect the thalli of crustose and foliose lichens, often causing localized discoloration or distortion of the host tissue. The fungi produce lirellate ascomata that are typically pale brown to gray, and their asci contain 8 ascospores that are ellipsoid and hyaline.

The most frequently cited species are Poraenia viridis, which is commonly associated with the lichen Cladonia rangiferina, and Poraenia formanekiae, reported from Saxifraga lichens. Studies of Poraenia fruiting bodies have been useful for understanding the coevolution of lichens with their epiphytic fungi. Molecular phylogenetic analyses place Poraenia in a clade distinct from other Stictidaceae, indicating a unique evolutionary pathway within the group.

Ecologically, Poraenia species are generally considered mild pathogens; they rarely cause severe damage to their lichen hosts, but in high densities can reduce photosynthetic area. The genus is of interest to lichenologists and mycologists as it exemplifies the complex symbiotic relationships that can exist among fungi, algae, and lichen-forming partners.