Description: O. corticola is not uncommon on the deeply shaded bark of old, wayside or woodland trees in Ireland. The grey-green to dull brown thallus is spotted with large (0.2-0.7mm diam.) pale grey to ochre-coloured soredia which can merge to form patches several millimetres across. Spot tests are negative therefore separating it from O. gyrocarpa. In old coppice woodlands fringing established river valleys, it is often found in the company of other shade-tolerant lichens such as Enterographa crassa and Schismatomma cretaceum. Discs are unknown. Thinly scattered throughout Ireland; absent from the extreme west.

Key Identification Features:

• Dull brown thallus scattered with flat, ochre, or often faded greenish-grey coloured soralia; reactions negative
• Low down on oaks in old coppice woodland; usually on deeply shaded tree boles.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Thelopsis corticola at iNaturalist World Species Observations database.