Description: This is a small, common, crustose species with a pale grey, thinly defined thallus occurring on the trunks and branches of basic-barked trees. The tiny hemispherical discs (0.2-0.8mm diam.) are pale to dark brown. It occurs fairly frequently in suitable habitats throughout Ireland.

Key Identification Features:

• The hemispherical, brownish fruits indicate this species. The equally frequent Bacidia laurocerasi has generally larger (to 1mm diam.) and more convex darker discs
• The size and paleness of the discs helps to separate it from lookalikes; the nature of the habitat is also helpful.

Original text submitted by Simon Davey

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

iNaturalist: Bacidia arceutina at iNaturalist World Species Observations database.