• Arthothelium orbilliferum (Almq.) Hasse
Arthothelium orbilliferum
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This very rare epiphyte of holly in western and south-western Ireland is a specialist ravine-woodland species. The thallus is grey or creamy white surrounded by a brown line. The black, non-pruinose discs (to 0.7mm diam.) are rounded but soon fracture from the centre outwards. Under the microscope the muriform spores have two to three longitudinal divisions (septa).

Key characteristics

  • A species of western ravine-woodland; holly favoured as host
  • Creamy white thallus, discs black, rounded, unfrosted, disintegrating at the centre; spores, muriform with two to three longwise divisions.

Original text submitted by Vince J. Giavarini

 Simms, M. J., (2016). Arthothelium orbilliferum (Almq.) Hasse. [In] LichenIreland. Accessed on 2018-07-16.