Description: This is a mosaic-forming species of coastal siliceous rock, especially sheltered vertical faces. It closely resembles the common cliff lichen Tephromela atra, with its white-grey warty thallus and black discs, which is unfortunate since it can often grow with it. On poorly colonised smooth rock faces, R. confragosa is conspicuous by its black, outwardly-spreading prothallus. In the field, the Pd+ yellow spot test helps separate it from Tephromela atra. Spores: one-septate with angular locules. In Ireland, the species is very rare.

Key Identification Features:

• Thallus white-grey, Pd+ yellow surrounded by a black prothallus
• Discs black; spores brown, one-septate, ellipsoid with jagged locules; vertical shaded acid rocks: coastal.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Rinodina confragosa at iNaturalist World Species Observations database.