Order: Lecanorales Family: Porpidiaceae
Species: Clauzadea monticolaGrowth type crustose. Left identified by J Douglass
Photos: On concrete walls. Co. Cork, SW Ireland.
Thallus dark grey or grey-brown, +/- immersed, prothallus absent. The sessile, convex black apothecia become reddish when wet but are never pruinose. Can resemble perithecia when dry. Hypothecium is reddish-brown. Asci 8-spored with simple, colourless, thin-walled spores, (6-)8-12(-14) x 4-9 Ám. Microscope photograph below.
Chemical reactions negative
Common and widespread on calcareous rocks and mortared walls.
Similar: Lecidella stigmatea: Thallus K+/- yellow. Hypothecium colourless or pale yellow. Sarcogyne regularis: Pruinose discs reddish when wet. Multi-spored ascus.