Description: Thallus in tufts to 3 cms long, erect axes terete, polysiphonous with 6 pericentral cells, ecorticate. Branches complanate and alternate.

Habitat: Epilithic at extreme low littoral.

Distribution: In the British Isles known only from Devon in England: Devon and Pembroke in Wales. Europe: Mediterranean, Spain and France. Pacific coast of North America: California. Further afield: Japan.

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

iNaturalist: Pterosiphonia pinnulata at iNaturalist World Species Observations database.

WoRMS: Pterosiphonia pinnulata at World Register of Marine Species. Accepted name: Xiphosiphonia pinnulata (Kützing) Savoie & G.W.Saunders, 2016. AphiaID: 1027803.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Rhodomelaceae; Pterosiphonieae; Pterosiphonia