Description: The very rare A. lirellans was formerly known from Killarney, County Kerry and from a single site in Donegal. It occurs on smooth-barked trees, especially the branches (not trunk) of holly and in rather remote habitats such as sheltered ravines, so it is possible the species continues to thrive. It could be mistaken for Arthonia punctiformis but under the microscope it is quite different with honeycombed (muriform) spores showing transverse cells with one longitudinal division only.

Key Identification Features:

• Like Arthonia punctiformis but with muriform spores, the transverse cells showing just one longitudinal division
• Often on smooth branches of trees growing in remote places such as sheltered ravines.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Arthothelium lirellans at iNaturalist World Species Observations database.