Irish lichens
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Family: Caliciaceae
Species: Diplotomma alboatrum Photos: On concrete wall, Kilcolman, Co. Limerick, Ireland. Very variable, the rather thick white, pale or dark grey thallus smooth, cracked or granulose. Apothecia are flat becoming convex, the black discs often pruinose, thalline margin sometimes present. Asci 8-spored, spores brown, 1-3 septate becoming submuriform or muriform when mature, (11-)15-20(-30) x (6-)8-10(-17) µm. Chemical reactions and UV negative. On basic or calcareous rocks, stonework and mortar, occasional on nutrient-enriched, basic-barked trees and worked timber. Similar: Diplotomma pharcidium is rare on smooth nutrient-rich bark. Considered to be possibly synonymous with D. alboatrum |
Diplotomma alboatrum. June 2025