The species was first distinguished by Carmichael, as Ceramium acanthonotum, in his unpublished Algae Appinensis, the manuscript of which is now preserved at the Herbarium of the Royal Botanic Gardens, Kew. Harvey (in Hooker, 1833), in publishing Carmichael's description, regarded the species merely as a variety of C. ciliatum. Agardh (1844) raised the variety to specific status, and it is as C. acanthonotum that the species has been known generally. Kiitzing (1841), 1 in a revision of the genus Ceramium, had described the entity independently as Acanthoceras shuttleworthianum; the specific epithetshuttleworthianum has priority overacanthonotum [see Article 60 of the International Code of Botanical Nomenclature (Lanjouw, 1956)]. The priority of the epithet shuttleworthianum was indicated, independently, by both Silva (1959) and Dixon (1959); of the two publications, that by Silva is the earlier.