Description: Thalli erect, hollow but clearly flattened. Elongated to 40 cms or more in length and to 2 cms wide.

Habitat: Rare. Epiphytic and epilithic mainly sublittoral to 10 m.

Distribution: Generally south-western in the British Isles from the Shetlands to the Channel Isles. Europe: Mediterranean, Atlantic coasts of Spain and France, Denmark, Baltic Sea, Norway, Faroes, Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island, New Jersey, Delaware, Maryland and Virginia. Further afield: Canary Islands, Australia and South Africa.

Similar Species: Other species of Asperococcus are similar. A.fistulosus is cylindrical and linear. A.bulbosus is inflated and bulbosus. A. scaber is solid, not hollow and less than 13 mm long.

Key Identification Features:

• Dotted all over with sori of colourless hairs and sori.

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

iNaturalist: Asperococcus compressus at iNaturalist World Species Observations database.

WoRMS: Asperococcus compressus at World Register of Marine Species. Accepted name: Asperococcus ensiformis (Delle Chiaje) M.J.Wynne, 2003. AphiaID: 376395.

Classification: Biota; Chromista; Harosa; Heterokonta; Ochrophyta; Phaeophyceae; Fucophycidae; Ectocarpales; Chordariaceae; Asperococcus