Description: Thallus terete to 40 cms or more long, erect, with distinct corticate main axis to 1 mm thick. Branches generally opposite. Axes with whorles of short lateral uniseriate filaments except towards the base.

Habitat: Epilithic, occasionally epiphytic. Generally sublittoral to 8 m or more.

Distribution: Generally distributed around the British IslesEurope: Mediterranean and the Black Sea, Portugal, Atlantic coasts of Spain and France, Denmark, Baltic, Norway, Sweden. Further afield: Atlantic coast of North America: Massachusetts, Rhode Island, New Jersey, Virginia, North Carolina, Caribbean, the Canary Islands and Australia .

Key Identification Features:

• Corticate main axes and whorls of short laterals.

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

iNaturalist: Arthrocladia villosa at iNaturalist World Species Observations database.

WoRMS: Arthrocladia villosa at World Register of Marine Species.