Description: This uncommon aquatic crustose lichen can be recognised in the field by its K+ yellow or red, Pd+ orange, spot test reactions. The thallus is black-olive green changing to grass green when wetted within the amphibious zone or a stream or river. Discs are common, crater-like. Often found squeezed between the thalli of other lichens such as Rhizocarpon lavatum and Ionaspis lacustris by searching bouldery sections of tree-lined river corridor. In Ireland: occasional in upland areas.

Key Identification Features:

• Round, crater-like discs, almost black on a green to black thallus; Pd+ orange, K+ yellow or red (this last reaction sometimes patchy)
• Growing in amphibious zone of shaded, upland streams and rivers.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Aspicilia laevata at iNaturalist World Species Observations database.