Description: At first sight this lichen may seem identical to X. parietina (described elsewhere), a common species of nutrient-rich habitats, whereas X. calcicola is always associated with calcareous substrata such as concrete posts and cement tiles. Unlike X. parietina the centre of the bright yellow-orange thallus of X. calcicola is packed with coarse, granular-shaped outgrowths (isidia). Also, the edge of the disc or exciple in X. calcicola is rough and jagged, but smooth in X. parietina. Throughout Ireland.

Key Identification Features:

• Thallus centre covered in sand grain-like isidia
• Discs slightly raised with jagged, sometimes granular, exciples.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Xanthoria calcicola at iNaturalist World Species Observations database.