Description: Searching the limestone headstones in an old churchyard is the easiest way to familiarise oneself with this species. Like many tiny, easily overlooked crustose species, this has a beige to pale brown thallus and rather small, reddish-brown to black discs without a distinctive margin. Under a hand lens the 1 margin may appear as a lighter rim around the disc. The species occurs on limestone and calcareous man-made substrates, and is common in suitable habitats throughout Ireland.

Key Identification Features:

• Numerous tiny discs (to 0.35mm diam.), on a pale brown slightly cracked thallus growing tight against the stone, discs red-brown
• It is most likely to be confused with Catillaria chalybeia that occurs on more acid substrates, but has darker, usually black apothecia and a more pronounced rim around the disc.

Original text submitted by Simon Davey

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

iNaturalist: Catillaria lenticularis at iNaturalist World Species Observations database.