Description: Thallus erect to 11 cms long with terete axes and many fine polysiphonous branches. Pericentral cells 7 - 8 and ecorticate.

Habitat: Very rare. No details available.

Distribution: in the British Isles: only three records, one 19th century from Cornwall and two 20th century records one from from south Walesthe other from Co. Galway. Europe: Mediterranean, Portugal and France. Further afield: Bermuda.

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

iNaturalist: Polysiphonia foetidissima at iNaturalist World Species Observations database.

WoRMS: Polysiphonia foetidissima at World Register of Marine Species. Accepted name: Vertebrata foetidissima (Cocks ex Bornet) Díaz-Tapia & Maggs, 2017. AphiaID: 1027781.

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