Description: Gametangial fronds stiff, erect and wiry, almost black in colour, growing to a maximum of 15 cm long. The tetrasporangial phase (Porphyrodiscus simulans) is crustose and grows to 30 cms in diameter.

Habitat: Epilithic in rock pools of the lower littoral and in the sublittoral to a depth of 12 m.

Distribution: Generally common around the British Isles. Europe: Azores, Portugal, Atlantic coasts of Spain and France, Netherlands, Baltic Sea, Norway, Faroes, Spitzbergen and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and New Jersey. Further afield: Arctic Sea circumpolar to Baffin Bay, Pacific and Indian Oceans.

Key Identification Features:

• Gametangial thallus unmistakable due to its wiry nature. The crustose phase however could be confused with other encrusting species.

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

iNaturalist: Ahnfeltia plicata at iNaturalist World Species Observations database.

WoRMS: Ahnfeltia plicata at World Register of Marine Species.