Description: Medium-sized plants, less than 4 cms long, flattened and deviding dichotomously up to 3 times with internal cystocarps.

Habitat: Very rare. Low littoral and upper littoral.

Distribution: Generally western in distribution recorded from a few sites in Ireland, south-west England and one in Scotland. Europe: Azores, Portugal, Spain and France.

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

iNaturalist: Ahnfeltiopsis devoniensis at iNaturalist World Species Observations database.

WoRMS: Ahnfeltiopsis devoniensis at World Register of Marine Species.