Description: Thallus forming small spots up to 1 mm across on the host. At the periphery monostromatic branches radiate out, in the centre the cells form erect unbranched filaments closely packed in a turf-like manner.

Habitat: Rare. Epiphytic on Laminaria in the low littoral and shallow sublittoral.

Distribution: Recorded from scattered sites around the British Isles, probably under-recorded. Europe: Portugal and Spain, France, Netherlands, Denmark, Sweden, Norway, Faroes and Iceland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island and Virginia. Further afield: California in the Pacific coast of the U.S.A.

Similar Species: There are a number of similar species growing as epiphytes or epilithic - all very small and difficult to identify. Microscopic examination is required.

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

iNaturalist: Myrionema corunnae at iNaturalist World Species Observations database.

WoRMS: Myrionema corunnae at World Register of Marine Species.