Cartilaginous, dark purplish-red, flattened fronds, 2 mm wide, to 200 mm high. Pinnate or bipinnate, often bare at base, branches opposite or alternate, often tapering at both ends; frequently give a 'Christmas-tree' appearance. Fronds in loose tuft from a rhizoidal base.

Thallus dark brownish-red, commonly growing in dense tufts about 4 cm high, and composed of prostrate axes that give rise to flattened erect axes. Branching pinnate to irregularly opposite with uniaxial growth from single apical cells. Inner structure pseudoparenchymatous, with long, slender, thick-walled rhizine cells filling the spaces between elongated medullary cells that are surrounded by a three-layered cortex of smaller pigmented cells

Key characteristics: Larger, darker and more purplish-red than Gelidium pusillum or G. pulchellum; normally, Pterocladia is not found fringing the edges of pools like the latter. Main axes are generally more flattened and apices more obtuse than G. pulchellum.

Perrone, C., Felicini, G.P. & Bottalico, A. (2006). The prostrate system of the Gelidiales: diagnostic and taxonomic importance. Botanica Marina 49: 23-33.

Santelices, B. (1999). Taxonomic status of the species originally ascribed to the genus Pterocladia (Gelidiales, Rhodophyta). In: Taxonomy of Economic Seaweeds with reference to some Pacific species Vol. VII. (Abbott, I.A. Eds) Vol.7, pp. 71-80. La Jolla, California: California Sea Grant College System.

Shimada, S. & Masuda, M. (2002). Japanese species of Pterocladiella Santelices et Hommersand (Rhodophyta, Gelidiales). In: Taxonomy of Economic Seaweeds with reference to some Pacific species. Vol. VIII. (Abbott, I.A. & Mcdermid, K.J. Eds) Vol.8, pp. 167-181. La Jolla: California Sea Grant College.

Xia, B.M. & Wang, Y.Q. (1999). Taxonomic studies on Pterocladiella (Gelidiaceae, Gelidiales, Rhodophyta) from China. In: Taxonomy of Economic Seaweeds with reference to some Pacific species Vol. VII. (Abbott, I.A. Eds) Vol.7, pp. 81-86. La Jolla, California: California Sea Grant College System.

Xia, B.M. (2004). Flora algarum marinarum sinicarum Tomus II Rhodophyta No. III Gelidiales Cryptonemiales Hildenbrandiales. pp. [i]-xxi, 1-203, pls I-XIII. Beijing: Science Press.

Basionym: Fucus capillaceus S.G.Gmelin

Type locality: Locus, Mare mediterraneum [Mediterranean Sea] (Gmelin 1768: 146). Lectotype: original illustration (Gmelin , 1768, pl. 15 fig.1). (epitype) (Womersley & Guiry 1994: 139).