Description: Smooth encrusting thallus up to 5 cms in diameter and 3 mm thick. Thin wavy margin without orbital ridges. Conceptacles raised.

Habitat: Common. Epilithic on rock, shells etc in shallow sublittoral sheltered areas. Reported from deep waters.

Distribution: Throughout the British Isles: England, Scotland, Wales and Ireland. Europe: Mediterranean, Spain, Balitc and Norway. Further afield: Canary Isles and Japan.

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

iNaturalist: Lithothamnion sonderi at iNaturalist World Species Observations database.

WoRMS: Lithothamnion sonderi at World Register of Marine Species. Accepted name: Lithothamnion sonderi Hauck, 1883. AphiaID: 145178.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Corallinophycidae; Hapalidiales; Hapalidiaceae; Lithothamnion