Description: This rare, aquatic crustose lichen has a grey to pale brown thallus with immersed discs that are black but become browner when wet, surrounded by a thin margin. Under the microscope the spores appear to have the distinctive pattern of an elongated cross at their centres. R. fimbriata favours nutrient-enriched rock by streams, rivers, loughs and tarns. In Ireland, it has only been recorded in County Kerry but should occur more widely on siliceous sandstones and slates.

Key Identification Features:

• Grey to pale brown thallus with immersed black discs; on nutrient-enriched rock by rivers and lakes, especially at confluence points
• Spores have the distinctive pattern of a cross at their centres; thallus K-.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Rinodina fimbriata at iNaturalist World Species Observations database.