It comprises a single species,[2] Joergensenia cephalodina, which is a corticolous (bark-dwelling), squamulose lichen found in southern South America.
[3] The genus was established in 2008 by the lichenologists Alfredo Passo, Soili Stenroos, and Susana Calvelo to accommodate this species, which phylogenetic analysis showed was only distantly related to Psoroma and Pannaria.
[4] The genus is Joergensenia characterised by its squamulose to almost foliose thallus, conspicuous cephalodia containing the cyanobacterium Scytonema, and distinctive ascus structure.
The ascus apex has a strong amyloid reaction revealing a compact cap-shaped plug, which differs from the apical structures found in other Pannariaceae genera.
Molecular phylogenetic analyses place Joergensenia in a basal position within the Pannariaceae, grouping with genera like Parmeliella and Degelia rather than with the core Psoroma-Pannaria clade.
[4] The apothecia (fruiting bodies) are lecanorine in form, meaning they have a rim (called the thalline exciple) that contains algal cells and looks similar to the thallus.
[4] This type, with a completely amyloid axial chamber, was later termed Joergensenia-type; it is one of five unique ascus structures that have been reported in the order Peltigerales].
The individual squamules are up to 3 mm long, initially rounded but becoming incised (cut into) and somewhat elongated at the thallus margin, giving mature specimens a placodioid (forming a crust-like rosette) appearance.
[4] Chemically, J. cephalodina contains pannarin, which gives a distinctive orange reaction with para-phenylenediamine (a common spot test for lichen substances).