Description: Hard crusts, growing to 10 cms in diameter strongly adhering to the surface, very dark in colour showing concentric rings.

Habitat: Rare. Epilithic or epiphytic on crustose coralline algae. In the upper sublittoral to 13 m.

Distribution: South-west coasts of the British Isles including Ireland, Lundy, Isle of Man and the Channel Isles. Europe: Portugal, Spain, France. Further afield: Morocco and South Africa.

Similar Species: Other species of Peyssonnelia and the tetrasporic phase (Haematocelis rubens J. Agardh) of Schizymenia dubyi (Chauvin ex Duby) J. Agardh.

Key Identification Features:

• The concentric rings help to distinguish this species from the others in the genus.

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

iNaturalist: Peyssonnelia atropurpurea at iNaturalist World Species Observations database.

WoRMS: Peyssonnelia atropurpurea at World Register of Marine Species.