Description: The thin, grey-brown thallus of this rare crustose lichen which can grow to cover large areas of bark is scattered with tiny pale-fawn to brown specks of powder (soralia) that react C+ red. Known only from Killarney, County Kerry where it grows on the trunks of old oaks in ancient woodlands O. fumosa is extremely localised. No other species can be confused with it.

Key Identification Features:

• The combination of thin, grey-brown spreading thallus, tiny spotted with fawn-coloured soralia reacting C+ red is diagnostic
• On oaks in ancient woodland.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Opegrapha fumosa at iNaturalist World Species Observations database.