Thick, flattened, subcartilaginous, ± palmate, deep crimson fronds, to 200 mm high, with short wedge-shaped stipe from small discoid base. Frond ± deeply cleft into wedge-shaped segments, themselves divided subdichotomously, apices rounded, margins smooth or fringed with minute proliferations.

A short soft, fleshy thallus arises and expands immediately from a small round (discoid) holdfast. The stipe is inconspicuous or absent and the crimson, brownish or purple-red fronds are much divided spreading out into wedge shaped divisions of about 1-3 cm broad. The whole blade can be up to 15 cm long and fan shaped with overlapping sections. Frond tips are rounded and end in tiny marginal leaflets giving a fringed appearance.

Often confused with Cryptopleura ramosa with which it often grows and can be distinguished if Cryptopleura ramosa shows iridescence as Callophyllis lacinata does not.

Original publication: Kützing, F.T. (1843). Phycologia generalis oder Anatomie, Physiologie und Systemkunde der Tange... Mit 80 farbig gedruckten Tafeln, gezeichnet und gravirt vom Verfasser. pp. [part 1]: [i]-xxxii, [1]-142 , [part 2:] 143-458, 1, err.], pls 1-80. Leipzig: F.A. Brockhaus.

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

Basionym: Fucus laciniatus Hudson

Type locality: Yorkshire, England (). Lectotype: Unlocalised, undated specimen. BM “provisional lectotype status