Description: Thallus minute. As small spots on the host. Base of endophytic filaments within the fronds of Laminaria, breaking through the surface with erect closely packed filaments, rarely branched, with hairs.

Habitat: On and in the fronds of Laminaria.

Distribution: A few scattered records around the British Isles including the Shetlands and the Channel Islands. Europe: France, Netherlands, Baltic Sea, Norway, Faroes, Iceland. Greenland. Atlantic coast of North America: Canada, Maine, New Hampshire, Massachusetts, Rhode Island, Connecticut and Long Island. Further afield: British Columbia, Washington, Oregon, California and Japan.

Similar Species: Like other endophytic genera, Cylindrocarpus, Endodictyon and Micosyphar microscopic examination is required for determination.

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

iNaturalist: Gononema aecidioides at iNaturalist World Species Observations database.

WoRMS: Gononema aecidioides at World Register of Marine Species. Accepted name: Laminariocolax aecidioides (Rosenvinge) A.F.Peters, 1998. AphiaID: 162814.

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