Description: Thallus encrusting and firmly attached to substrate. Confluent specimens to 3 cms or more in diameter.

Habitat: Rare. Epilithic in the lower littoral.

Distribution: Apparently only found in the south east coasts of England and on the east coast of Ireland at Dublin. Europe: France.

Similar Species: All other small brown encrusting algae are similar and require microscopic examination for determination.

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

iNaturalist: Pseudolithoderma roscoffense at iNaturalist World Species Observations database.

WoRMS: Pseudolithoderma roscoffense at World Register of Marine Species. Accepted name: Pseudolithoderma roscoffense Loiseaux, 1968. AphiaID: 144991.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Dictyotophycidae; Sphacelariales; Lithodermataceae; Pseudolithoderma