''Dirina fallax'' is a species of saxicolous (rock-dwelling), crustose lichen in the family Roccellaceae. It is found in the western Mediterranean, the Atlantic coasts of both Africa and Europe (extending from Scotland to Morocco), and central Europe, where it grows on siliceous and

acidic rock Acidic rock or acid rock refers to the chemical composition of igneous rocks that has 63% wt% SiO2 content. Rocks described as acidic usually contain more than 20% of free quartz. Typical acidic rocks are granite or rhyolite. Term is used in che ...

s. In 2017, it was reported from the

Abrau Peninsula The Abrau Peninsula is a north-western spur of the Greater Caucasus Mountain Range, located on the Black Sea between Novorossiysk and Anapa, in the Krasnodar Region of Russia. It contains the Utrish State Nature Reserve. Climate and ecology T ...

in Russia.

Taxonomy

The lichen was first described scientifically by Giuseppe De Notaris in 1846, from specimens collected in Sardinia, Italy. Tehler and colleagues unsuccessfully searched Italian herbaria for the type specimen, and therefore assigned a neotype from a specimen also collected in Sardinia.

Description

The lichen has a creamy greyish-brown, crustose thallus with a somewhat roughened surface (0.1–1.5 mm thick), and a white, chalk-like medulla. When

soralia Soredia are common reproductive structures of lichens. Lichens reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungal hyphae wrapped around cyanobacteria o ...

are present (typically when apothecia are absent), they are to . If apothecia are present, they have a circular outline and a diameter of 0.1–2.0 mm; the apothecial is white-grey, , and encircled by a . Ascospores measure 18–24 by 5–6

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

. ''Dirina fallax'' contains the lichen products erythrin and

lecanoric acid Lecanoric acid is a chemical produced by several species of lichen.ubChem - Lecanoric acid"> Lecanoric acid is classified as a polyphenol and a didepside and it functions as an antioxidant. The acid is named after the lichen ''Lecanora''. The acid ...

, as well as two unidentified substances. The expected results of chemical spot tests are C+ (faint red) on the thallus surface, C− on the medulla, and C+ (red) on the disc.

References

{{Taxonbar, from=Q21269753 fallax Lichen species Lichens described in 1846 Lichens of Europe Lichens of North Africa Taxa named by Giuseppe De Notaris