Description: Thallus flat up to 30 cms long, membranous, irregularly split into wedge-shaped segments broadest near the leading edge, without a midrib. The spores are borne in lines seen as wavy lines across the frond.

Habitat: Locally common in the south-west. Epilithic in the sublittoral.

Distribution: Southern distribution in the British Isles: Galway Bay, near Dublin and on the south coast of Ireland, Isle of Man, Wales, southern England from Cornwall to Kent. Europe: Mediterranean, Azores, Portugal, Atlantic coast of Spain and France. Further afield: Canary Islands, Mauritania, Senegal, Algeria and Indian Ocean.

Similar Species: Cutleria multifida is similar but divided into narrow sections, irregularly dichotomous.

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

iNaturalist: Taonia atomaria at iNaturalist World Species Observations database.

WoRMS: Taonia atomaria at World Register of Marine Species.