Species: Aspicilia contortaGrowth type crustose
Photos: On concrete fences. Co. Cork, SW Ireland.
Greenish-grey thallus with separate, convex areoles that later merge and become paler in colour. Prothallus indistinct. Apothecia are immersed black discs, often covered with bluish-white pruina, usually single in centre of each areole. The asci are 4-spored, spores 20 x 11 Ám. Epithecium olive-green, K+ orange-yellow.
Thallus: Chemical reactions negative.
Common on concrete, mortar and hard calcareous rocks, very tolerant of nutrient enrichment. Two sub-species; subsp. contorta and subsp. hoffmanniana, photographs below.
Similar: Aspicilia calcarea
Aspicilia contorta. On concrete, Co. Cork. December 2011 and January 2012