Description: This is a distinctive and sizeable crust of siliceous, maritime rocks with a thick, irregularly cracked, dark-grey to violet-black thallus. The black discs are large (0.8-1.5mm diam.), flat and immersed. The thallus is C+ orange-red which separates it from similar species. Widely but thinly distributed in Ireland, coastal.

Key Identification Features:

• Grows with other crustose lichens in grey zone (directly above the orange zone) of maritime rocks; has a thick dark-grey to violet-black thallus, the mauve tinge predominating
• Large immersed discs without a raised edge, thallus C+ orange-red.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Rinodina luridescens at iNaturalist World Species Observations database.