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(Map updated: 11 August 2009)

This is a very distinctive species especially when seen in the field and there are few lookalikes to confuse the beginner. Search for it always on damp, vertically inclined acid rock especially where there is seepage. It is frequent along upland stream valleys where the watercourse flows through shallow ravines. On a dry day it should be possible to view it in both the wet and dry state. The smooth, creamy-white, irregularly cracked thallus is spotted (like a leopard) with flat, black, irregular-shaped discs (0.2-0.5mm) having an almost non-existent margin, reminiscent of Arthonia or Aspicilia. Spot tests C-, K+ yellow, Pd+ yellow will confirm it. Western Ireland.

Key characteristics

• Thallus cracked, pale grey to creamy white, spotted with black irregularly-rounded, discs lacking conspicuous margins
• Strongly associated with intermittent seepage over upland siliceous rocks; the thallus of Amygdalaria pelobotryon (described elsewhere) is lumpy-convex and tests C+ red.

NBN Atlas mapping: Species account : NBN Atlas UK Species Observations database

iNaturalist: Species account : iNaturalist World Species Observations database

Original text submitted by Vince J. Giavarini