The following taxon apparently lies within the circumscription of Ceramium cimbricum but has not yet been transferred or reduced to synonymy:
Ceramium fastigiatum Harvey forma flaccidum H. Petersen in Børgesen, 1918: 241–243, fig. 231 (syntype localities: various in Virgin Islands).—Basson, 1979: 72, pl. XII: figs. 68, 69.— Islam & Aziz, 1987: 215, pl. II: fig. 11; pl. V: figs. 30, 31.— Basson, Mohamed, & Arora, 1989: 36.— Basson, 1992: 226.— Kalugina-Gutnik, Perestenko, & Titlyanova, 1992: 20 (table 1).— Stegenga & Bolton, 1992: fig. 3, table I.— Titlyanova, Perestenko, & Kalugina-Gutnik, 1992: 43.
INDIAN OCEAN DISTRIBUTION: Bahrain, Bangladesh, Saudi Arabia, Seychelles, South Africa.