Order: Verrucariales       Family: Verrucariaceae Species: Verrucaria muralis Growth type crustose Photos: On rock. Ballinagree, Co. Cork, Sw Ireland White to greenish-white thallus, immersed, smooth or cracked. Black perithecia are immersed or prominent, leaving shallow pits in substrate. Spores (17-)20-24(-27) x (7.5-)10-12.5(-14.5) µm. Microscope photograph below. Common on bricks, mortar, soft limestone rocks and on pebbles

Microscope photograph

Verrucaria muralis . April 2012