Species: Acarospora fuscataGrowth type crustose.
Photos: On well-lit acidic upland rock, Ballingeary, Cork, SW Ireland.
Looks like dried, cracked mud with angular areoles ranging in colour from yellow-brown to reddish-brown. Sunken reddish-brown discs. Asci with >100 minute spores, spores 4-6 x 1-1.5 Ám.
Chemical reactions: K-, C+ red, KC+ red
Prefers nitrogen-enriched siliceous sites. Wall tops, churchyard monuments, rock outcrops and ledges, bird-perching sites. Not found on limestone.
Similar: A. impressula K-, C-, and A. smaragdula K+ red
Acarospora fuscata. Ballingeary area, Co. Cork. January 2009