Description: Tufted, very small to 2 mm tall, filaments erect, rarely branched and monosiphonous.

Habitat: Very rare. Epiphytic on Zosters in the lower liottoral and upper sublittoral.

Distribution: Widely distributed around the British Isles. Europe: France, Denmark, Baltic Sea and Norway. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island and Delaware. Further afield: Pacific: Canada, U.S.A. and Indo-Pacific.

Similar Species: Similar to other small tufted algae, requires microscopic examination for identification.

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

iNaturalist: Halothrix lumbricalis at iNaturalist World Species Observations database.

WoRMS: Halothrix lumbricalis at World Register of Marine Species. Accepted name: Halothrix lumbricalis (Kützing) Reinke, 1888. AphiaID: 144944.

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