ASCOMYCOTA | LECANOROMYCETES > PERTUSARIALES > Megasporaceae

Common name:             -

Synonyms:                    Aspicilia contorta, ssp.contorta

Habitat:                           Urban (for this entry)

Substrata:                      Rock, stone

Growth form:                 Saxicolous

Thallus:                  Crustose

Apothecia:                     Lecanorine

BLS identity rating: Graded 1/5 (identification should be straightforward)

Thallus variable depending on the substratum and exposure to the sun, but typically formed of separate, smooth, rounded, convex areoles, usually scattered, although later becoming merged; colour dirty whitish or greyish when dry, turning glaucous green if moist; prothallus indistinct; apothecia 0.2-0.6mm dia., immersed, with the flat black discs often covered with a bluish or greenish-blue pruina, usually single in the centre of each areole, rarely two or three.

Circinaria contorta is a common species on hard calcareous rocks, concrete and mortar.

Formerly classified as Aspicilia contorta with two very similar subspecies, but now treated as a species in its own right under the genus Circinaria with the variant form hoffmanniana retaining its subspecies status, now Circinaria contorta ssp.hoffmanniana. The main distinguishing feature between the two forms is the shape of the areoles when merged together, which in hoffmanniana become distinctly angular, rather than rounded.