Description: The foliose phase (gametangial) in the life-history grows from a small holdfast and short stipe to form one or more delicate fronds, flattened and thin. Fronds to 30 cms or more in length branching irregular and from the margins. The tetrasporangial phase is crustose.

Habitat: Epilithic in the lower sublittoral to 25 m.

Distribution: Widespread, mainly western in the British Isles from the Shetlands to the Channel Islands. Europe: the Mediterranean, Spain, France, Denmark, Helgoland, Denmark and the Baltic. Further afield: Canary Islands and Morocco.

Similar Species: The tetrasporophyte is crustose and very difficult to distinguish from other encrusting algae. The gametophyte is very similar to Halymenia latifolia and some other red foliose red algae.

Key Identification Features:

• Delicate flat blades branching irregularily from the edges.

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

iNaturalist: Halarachnion ligulatum at iNaturalist World Species Observations database.

WoRMS: Halarachnion ligulatum at World Register of Marine Species. Accepted name: Halarachnion ligulatum (Woodward) Kützing, 1843. AphiaID: 145621.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Gigartinales; Furcellariaceae; Halarachnion