Description: This crustose epiphyte with a green-brown thallus of dispersed granules is only conspicuous on account of the dot-like speckles of buff-coloured, floury soredia which are produced across the surface of the tiny thallus. It is characteristic of oak and alder bark in high-level woodlands and of trees growing along upland river corridors where rainfall is above the average. The soralia are C (fresh bleach) + red. Northern and western Ireland.

Key Identification Features:

• Thallus green-brown, generally inconspicuous; acid bark in upland areas
• Numerous small, dot-like speckles (soralia), tiny, neat and buff-coloured; C + red.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Trapelia corticola at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Trapelia corticola at iNaturalist World Species Observations database.