Description: This crustose species with small, black, spherical discs (perithecia: to 0.4mm diam.) — often sunken into pits — occurs mostly on hard limestone. The thallus, which scratches orange with a fingernail, is pink-grey to brown. The species is relatively common in Ireland on hard limestone rocks.

Key Identification Features:

• The minute, black perithecia, the colour of the thallus, and its habitat, serve to suggest this species
• Under the microscope, the consistently three-septate spores should help to confirm it.

Original text submitted by Simon Davey

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

iNaturalist: Porina linearis at iNaturalist World Species Observations database.