Description: This small lichen with a white thallus and red-brown or orange-brown discs could easily be mistaken for a small poorly-developed Caloplaca species. It grows essentially on limestone screes and occupies shaded crevices and the undersides of stable fragments. The discs (K-) are at first concave. The ellipsoid spores can reach 17µm long; some spores are waisted at the septum. In Ireland, the species is known from Counties Galway and Armagh.

Key Identification Features:

• Small limestone-loving species with a white thallus and red or orange-brown (K-) discs; spores one-septate, some waisted
• On limestone screes; rare in Ireland.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Catillaria minuta at iNaturalist World Species Observations database.