Description: This crustose ‘bark-pimple’ lichen grows exclusively on hazel in old woodlands. It has the appearance of a rather robust A. ranunculosporum (described elsewhere) but has small naked discs (perithecia) not frosted by bark cells. It often occurs with Arthopyrenia carneobrunneola (brown stains on bark) on old hazel stands. Under the microscope, the two cells (compartments) of the one-septate spores are of more or less equal length. In Ireland: currently recorded from north-east and south-east only.

Key Identification Features:

• Only on hazel in established woodlands, often with Arthopyrenia carneobrunneola
• Pale yellow-brown thallus, with black, naked perithecia (<0.2mm diam.) containing one-septate spores, the cells of which are of roughly equal length.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Anisomeridium viridescens at iNaturalist World Species Observations database.