Description: Thallus filamentous, erect to 1 cm long, branching in one plane.

Habitat: Very rare. Usually epiphytic in the sublittoral to 25 m depth.

Distribution: Known in the British Isles only from counties Cornwall, Donegal and Kerry.

Similar Species: All species of Aglaothamnion and Callithamnion are similar and not easy to identify.

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

iNaturalist: Aglaothamnion diaphanum at iNaturalist World Species Observations database.

WoRMS: Aglaothamnion diaphanum at World Register of Marine Species. Accepted name: Aglaothamnion diaphanum L'Hardy-Halos & Maggs, 1991. AphiaID: 144493.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Callithamniaceae; Callithamnioideae; Callithamnieae; Aglaothamnion