Description: Thallus encrusting to at least 6 cms in diameter and up to 2 mm thick. Flat or irregularly lumpy, conceptacles domed, the old conceptacles become burried as the thallus grows and thickens.

Habitat: Rare. Epilithic on rock. Known only from the low littoral.

Distribution: A recently described species. In the British Isles known only from Dorset and Devon in England; Pembroke in Wales; Co. Clare in Ireland and the Channel Isles. Europe: Normandy and Brittany in France.

Similar Species: Phymatolithon lenormandii from which it is distinguished by the brown colour and white edges of P.brunneum.

Key Identification Features:

• Thallus brownish with white edges. Overgrowing P.lenormandii and P.purpureum.

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

iNaturalist: Phymatolithon brunneum at iNaturalist World Species Observations database.

WoRMS: Phymatolithon brunneum at World Register of Marine Species.