A small red alga (up to 17 cm in length), the fronds are channelled with a thickened edge and widen from a narrow stipe with disc-like holdfast. The channelling is often slight and is most noticeable at the base of the frond. Mature plants have conspicuous growths of short, shout papillae (reproductive bodies) on the fronds. The plant is dark reddish-brown to purple in colour and may be bleached. The common name false Irish moss is used as it may be confused with Chondrus crispus (Irish moss). The main features separating the two species being the channelled frond and appearance of reproductive bodies on mature plants.

Link for Algae Handbook (Pereira, 2010).

Original publication: Guiry, M.D., West, J.A., Kim, D.-H. & Masuda, M. (1984). Reinstatement of the genus Mastocarpus Kützing (Rhodophyta). Taxon 33: 53-63.

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Key characteristics: Inrolled margins, cystocarps in papillae.

Source of hydrocolloids - source of carrageenan

Bates, C.R., Saunders, G.W. & Chopin, T. (2005). An assessment of two taxonomic distinctness indices for detecting seaweed assemblage responses to environmental stress. Botanica Marina 48: 231-243.

Braune, W. (2008). Meeresalgen. Ein Farbbildführer zu den verbreiteten benthischen Grün- Braun- und Rotalgen der Weltmeere. pp. [1]-596, 266 pls. Ruggell: A.R.G. Gantner Verlag.

Guiry, M.D. & West, J.A. (1983). Life history and hybridization studies on Gigartina stellata and Petrocelis cruenta (Rhodophyta) in the North Atlantic. Journal of Phycology 19: 474-494.

Loiseaux-de Goër, S. & Noailles, M.-C. (2008). Algues de Roscoff. pp. [1]-215, col. figs. Roscoff: Editions de la Station Biologique de Roscoff.

Schories, D., Selig, U. & Schubert, H. (2009). Species and synonym list of the German marine macroalgae based on historical and recent records. Rostock. Meeresbiolog. Beitr. 21: 7-135.

Silva, P.C. (1952). A review of nomenclatural conservation in the algae from the point of view of the type method. University of California Publications in Botany 25: 241-323.

Zuccarello, G.C., Schidlo, A., McIvor, L. & Guiry, M.D. (2006). A molecular re-examination of speciation in the intertidal red alga Mastocarpus stellatus (Gigartinales, Rhodophyta) in Europe. European Journal of Phycology 40: 337-344, 3 figs, 7 tables.

Common names used in trade: Nadeltang {Ger}; Irish Moss {Eng}; carraigin

Basionym: Fucus stellatus Stackhouse

Type locality: western shores of England (Stackhouse 1797: 53, pl. 12). Type: Stackhouse;

Notes: The name has been typified with Stackhouse’s description in Withering (1797: 99); the original specimens have not been found. The figure in pl. 12 of Stackhouse (1797) could serve as a lectotype