Description: Thallus ecorticate, erect to 2 cms long. Branching in one plane, the lateral branches alternate, final ramuli alternate or secund.

Habitat: Epilithic in the sublittoral to about 15 m.

Distribution: Known in the British Isles only from a few sites in Co. Donegal and on the west coast of Scotland. Europe: France (Brittany). Further afield: Canary Islands.

Similar Species: Some species of Aglaothamnion.

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

iNaturalist: Compsothamnion decompositum at iNaturalist World Species Observations database.

WoRMS: Compsothamnion decompositum at World Register of Marine Species. Accepted name: Compsothamnion decompositum (J.Agardh) Maggs & L'Hardy-Halos, 1993. AphiaID: 144571.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Ceramiales; Ceramiaceae; Compsothamnioideae; Compsothamnieae; Compsothamnion