LichenIreland
  • Arthonia atlantica P.James
Arthonia atlantica
Click on map to open large map in new window
(Map updated: 11 August 2009)

This species grows below dry siliceous underhangs and in sheltered recesses in walls near the coast. It has a pale grey, scurfy thallus which looks unimpressive at first sight. However, closer inspection shows the presence of numerous iced-over discs joined together in a continuous mosaic reminiscent of Enterographa. Spores are two- to four-septate with an enlarged upper cell. The thallus tests Pd+ pale yellow or red. In Ireland, it is a western oceanic species and is known from Counties Kerry, Cork, Galway and Mayo, especially the offshore islands.

Key characteristics

  • Small, white to pale grey mosaic-forming crust with hidden Enterographa-like frosted discs; spores with enlarged upper cell
  • On the sheltered underhangs and shaded recesses of cliffs and walls along western coasts; Peterjamesia circumscriptum scratches orange with a finger nail.

Original text submitted by Vince J. Giavarini

 
 Simms, M. J., (2016). Arthonia atlantica P.James. [In] LichenIreland.
http://www.habitas.org.uk/lichenireland/species.asp?item=15489 Accessed on 2018-10-16.