Porpidiaceae Clauzadea metzleri Growth type crustose Chemical results negative Found on calcareous pebbles, rocks and walls. Occurs on hard and soft limestone, also on chalk pebbles Immersed thallus with lines or groups of black, non-pruinose discs (to 1mm) in shallow pits. Hypothecium reddish-brown. Spores simple, (15-)16-20(-28) x (6-)8-10(-12) µm. Microscope photograph below. Similar: C. immersa. Deeply immersed apothecia (to 0.5mm), smaller spores

Microscope photograph

Clauzadea metzleri
Godlingston Hill, the Purbecks, Dorset. October 2012