• Psorotichia schaereri (A.Massal.) Arnold
Psorotichia schaereri
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There are several inconspicuous, scurfy-bodied crusts which grow on limestone. Psorotichia schaereri is one such species that lingers in the shade. The granular-squamulose thallus is easily overlooked for Placynthium nigrum but the reddish, brown-black discs (0.2-0.6mm diam.) clearly mark it out as something different. The granules can be minutely isidiate so require close inspection. The spores are simple and ellipsoid usually within the range 14-18ųm long. Confined to shaded limestones where there may be some seepage or permanent dampness. Western Ireland.

Key characteristics

  • Small scurfy crust of minute, brownish granular-isidiate squamules (<1mm long); on shaded, mostly horizontal limestones — sometimes along seepage tracks
  • Discs reddish and convex when mature (like red ‘Fruit Pastilles’ not black as in Placynthium).

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Psorotichia schaereri (A.Massal.) Arnold. [In] LichenIreland. Accessed on 2018-07-20.