Description: Very small uniseriate filaments, branched with erect axes to 1 mm.

Habitat: Generally common, epiphytic on Alaria esculenta.

Distribution: Generally a north-western species in the British Isles. Recorded from the west and north of Ireland and Scotland. Europe: Portugal, Spain, N. France, Baltic Sea, Norway, Faeroes and Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts and Virginia. Further afield: the Canary Islands and Australia.

Similar Species: All species of Acrochaetium are similar, microscopic examination is usually required for identification.

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

iNaturalist: Acrochaetium alariae at iNaturalist World Species Observations database.

WoRMS: Acrochaetium alariae at World Register of Marine Species.