Description: Thallus of microscopic filaments up to 10 cells long with few branches. Cells with conspicuous hairs.

Habitat: Endophytic or epiphytic, creeping in the cell walls of other algae. Littoral and sublittoral.

Distribution: British Isles including the Shetlands: from scattered sites, rarely recorded, but probably rarely looked for. Europe: Spain, France, Netherlands, Baltic Sea, Norway and the Faroes. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island and Virginia.

Similar Species: Microscopic examination required for identification.

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

iNaturalist: Entocladia wittrockii at iNaturalist World Species Observations database.

WoRMS: Entocladia wittrockii at World Register of Marine Species.