Description: Thallus filamentous, erect, delicate and finely branched, 0.5 to 3 cms long growing in tufts.

Habitat: Epiphytic, epizoic and epilithic, mid-littoral to 18 m sublittoral.

Distribution: Widely distributed in the British Isles including the Orkneys. Europe: Mediterranean, Portugal, Atlantic coasts of Spain and France, Netherlands, Baltic Sea and Norway. Further afield: Canary Islands and Morocco.

Similar Species: All species of Aglaothamnion and Callithamnion are similar and not easy to identify.

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

iNaturalist: Aglaothamnion byssoides at iNaturalist World Species Observations database.

WoRMS: Aglaothamnion byssoides at World Register of Marine Species. Accepted name: Aglaothamnion tenuissimum (Bonnemaison) Feldmann-Mazoyer, 1941. AphiaID: 144501.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Callithamniaceae; Callithamnioideae; Callithamnieae; Aglaothamnion