Evernia illyrica
Evernia illyrica is a rare species of fruticose lichen in the family Parmeliaceae. It is native to Europe and North Africa. It grows in a hanging manner, reaching lengths of up to 30 cm, and attaches to its base by a single point. The lichen's main body is uniformly grey to whitish-grey with no distinct upper or lower surfaces, featuring rich but irregular branching patterns with branches that grow parallel to each other. Though reproductive structures are rare, when present they appear as -like formations up to 4 mm across with a brown centre surrounded by a thin rim. The species is extremely rare and endangered in Italy, and has been documented in well-preserved forests across Spain, Albania, Turkey, and Morocco, where it typically grows on large trees in undisturbed habitats.
Taxonomy
Evernia illyrica was first formally described as a new species in 1904 by the German lichenologist Alexander Zahlbruckner, who classified it as a subspecies of Evernia divaricata. Gustaf Einar Du Rietz elevated it to species status in 1926.Description
Evernia illyrica is a fruticose lichen that attaches to its substrate via a basal holdfast. It grows in a pendulous manner, reaching lengths of up to 30 cm. The thallus is not, instead displaying a uniform grey to whitish-grey colouration on all sides with a finish. It has rich but irregular branching patterns with mostly obtuse angles at branch junctions. The main branches generally grow parallel to each other, though they may become entangled, and are somewhat to angular in cross-section with a soft texture. These branches typically measure 0.5–1.5 mm in width and feature smooth surfaces or shallow longitudinal grooves. Scattered side branches appear throughout, with tips that sometimes darken and taper to a point or abruptly narrow.The of E. illyrica is thin and composed of arranged, small-celled fungal filaments. This cortex often degenerates in certain areas and frequently develops transverse cracks in older specimens, exposing the underlying medulla. The medulla is loosely structured, somewhat spider web-like in appearance, but often forms a very soft central strand that provides cohesion.
Reproductive structures are rare in this species. When present, they are in form,, and positioned laterally on the main branches. These apothecia measure up to 4 mm across, featuring a brown, flat surrounded by a thin. The internal structure includes a colourless, a brownish, and a colourless hymenium. The paraphyses are mostly simple, thick, and septate, while the is colourless.
The asci contain eight spores each and are clavate. Their turns blue when treated with potassium iodide and is penetrated by a faintly amyloid apical cushion with parallel or diverging flanks. The wall is K/I− but is surrounded by a K/I+ blue outer layer, characteristic of the Lecanora-type. The are single-celled, hyaline, ellipsoidal, measuring approximately 7 by 4 μm, and are often poorly developed. The pycnidia appear terminally on short side branches. The is. When subjected to chemical spot tests, the cortex is K+, C−, KC−, and P−. Chemical analysis reveals the presence of atranorin in the cortex and divaricatic acid in the medulla.