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(Map updated: 11 August 2009)

Despite belonging to the same tribe as the ‘bark pimple’ species, this lichen is not an epiphyte and grows exclusively on limestone. The grey immersed thallus with tiny, brown, half-embedded spherical discs (perithecia) containing narrow, oblong, one-septate spores could only be confused with Porina linearis which has spindle-shaped, three-septate spores. It occurs mostly on shaded, hard limestones. County Clare (The Burren); thinly scattered in the north.

Key characteristics

• Dark brown perithecia containing oblong, one-septate spores
• Grows on hard, shaded limestone rocks and boulders.

Original text submitted by Vince J. Giavarini