Description: Thallus in tufts erect to 5 cms. Axes terete polysiphonous and ecorticate, with small central cell and four pericentral cells. Rhizoids formed from pericentral cells remain in connection with them. Cystocarps ovoid to globular.

Habitat: Very rare. Epilithic from low water to 4 m.

Distribution: Recorded as common in the south of England from Dorset, Devon and Cornwall and from Wales.

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

iNaturalist: Polysiphonia devoniensis at iNaturalist World Species Observations database.

WoRMS: Polysiphonia devoniensis at World Register of Marine Species.