Description: The extremely minute scaly thallus of this yellow-grey or pale reddish-brown lichen develops on some of the most easily overlooked lichen habitats, for example, tiny fragments of undisturbed, rocky waste and old seashells. It has been found growing on piles of rock dumped on the edge of plantation woodlands. The scattered discs (0.2-0.6mm diam.) are very small, developing in the centre of the squamules like little circles. It is extremely local and scattered in northern and central Ireland and is often mistaken for other tiny lichens such as Thelocarpon.

Key Identification Features:

• Thallus present as tiny, pale stains on waste fragments of rock
• Discs, single and rounded; reactions negative.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Caeruleum heppii at iNaturalist World Species Observations database.