Description: Small encrusting thallus, orbicular to 2 mm in diameter.

Habitat: Epiphytic usually on Halopithys incurvus.

Distribution: Only known fron Hampshire, Dorset and the Channel Islands in the British Islas. Europe: Mediterranean, Atlantic coast of France. Further afield: Japan.

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

iNaturalist: Hydrolithon sargassi at iNaturalist World Species Observations database.

WoRMS: Hydrolithon sargassi at World Register of Marine Species. Accepted name: Hydrolithon sargassi (Foslie) Y.M.Chamberlain, 1994. AphiaID: 145122.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Corallinophycidae; Corallinales; Hydrolithaceae; Hydrolithoideae; Hydrolithon