Description: This is an abundant, shade-tolerant species of man-made, calcareous habitats, such as vertical limestone walls, mortar and limestone headstones. The small, chalky thallus covered with tiny black discs (to 1mm diam.), glazed over with an icing of pruina is distinctive. It may also occur on the enriched bark of basic trees such as ash.

Key Identification Features:

• The pruinose discs on a chalky-white thallus immediately indicates this species
• It reacts negative to all reagents.

Original text submitted by Simon Davey

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

iNaturalist: Diplotomma alboatrum at iNaturalist World Species Observations database.