Description: Thallus monosiphonous, ecorticate and erect to to 10 cms. Branches pseudodichotomously, the cells remaining cylindrical or only slightly inflated at the ends.

Habitat: Epilithic or epizoic at low littoral to 10 m.

Distribution: Recorded from the south-west coasts of the British Isles: Essex, Sussex, Hampshire, Dorset, Devon, Cornwall and Pembroke in England, Cork and Dublin in Ireland, also the Channel Isles. Europe: France, Netherlands and Denmark (as drift).

Similar Species: Griffithsia corallinoides when mature has inflated cells (pyriform) while those of G.devoniensis are cylindrical.

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

iNaturalist: Griffithsia devoniensis at iNaturalist World Species Observations database.

WoRMS: Griffithsia devoniensis at World Register of Marine Species.