Description: As suggested by the specific name, this lichen is rock-dwelling. It is in fact one of several Irish parasitic lichens. This species targets limestone lichens, especially Verrucaria which grow in pits embedded in the rock. The discs (lirellae: 0.2-0.3mm diam.) occur in small, scattered clusters and have three-septate spores. It occurs where Verrucaria grows on hard natural limestone as well as on limestone in churchyards and other local habitats. Northern and western Ireland.

Key Identification Features:

• Parasitic mostly on pit-forming Verrucaria lichens
• Thallus barely visible, discs tiny, superficial, three-septate.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Opegrapha rupestris at iNaturalist World Species Observations database.