Description: Thallus very small, filamentous, spreading over the substrate in patches bearing erect fronds in tufts to 0.8 cms. Opposite branches spreading in one plane.

Habitat: Epilithic and epiphytic. In littoral rock pools to 26 m depth.

Distribution: Widely distributed in the British Isles including the Shetlands. Europe: Mediterranean, Portugal. Further afield: the Canary Islands.

Similar Species: Ptilothamnion pluma can be distinguished from Spermothamnion repens by the rhizoids and erect axes which arise from near the middle of the prostrate axial cell in P.pluma.

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

iNaturalist: Ptilothamnion pluma at iNaturalist World Species Observations database.

WoRMS: Ptilothamnion pluma at World Register of Marine Species. Accepted name: Ptilothamnion pluma (Dillwyn) Thuret, 1863. AphiaID: 144689.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Wrangeliaceae; Lejolisieae; Ptilothamnion