Irish lichens
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Order: Arthoniales Family: Opegraphaceae
Species: Opegrapha vermicellifera Photos: Under dead branch of Cork Oak. Ardnagashel, Co. Cork, SW Ireland. Identified by Andy Acton Smooth, light to medium-grey thallus that can form large patches. Usually sterile with small, prominent pycnidia with white or pale grey pruina. Pycnidia semi-immersed when young, chestnut brown with pale ostiole. When fertile lirellae 0.6 to 1.2mm, slender, exciple sometimes furrowed or pruinose. The spores are 4-7 septate, 16-25 x 3-4 µm, the ends +/- pointed. Scarce in Ireland in shaded, dry recesses of basic-barked trees, rarely found on rock. Chemical reactions and UV negative. Similar: Lecanactis abietina, pycnidial pruina C+ red |
Opegrapha vermicellifera March 2010