Description: Thallus in dense tufts to 10 cms or more long. Terete, polysiphonous with 4 pericentral cells which may show cortication but only near the base. Rhizoids cut off from the pericentral cells.

Habitat: Common. Epilithic, epizoic and epiphytic in rock pools of the mid-littoral into the sublittoral at 20 m. Cystocarps globular to ovoid.

Distribution: Widely distributed in the British Isles. Europe: Spain, France and the Faroes.

Similar Species: Other species of Polysiphonia are similar and difficult to distinguish.

Key Identification Features:

• Pericentral cells with little or no cortication except near the base. Rhizoids cut off from pericentrals.

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

iNaturalist: Polysiphonia fibrata at iNaturalist World Species Observations database.

WoRMS: Polysiphonia fibrata at World Register of Marine Species. Accepted name: Leptosiphonia fibrata (C.Agardh) A.M.Savoie & G.W.Saunders, 2019. AphiaID: 1333554.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Rhodomelaceae; Polysiphonieae; Polysiphonia