THE TYPE SPECIES OF CERAMIUM (RHODOPHYTA), CERAMIUM VIRGATUM ROTH: TYPIFICATION AND PHYLOGENY

• Published in: Journal of Phycology
• Main Authors: Maggs A., C., McIvor, L. M., Evan, C. M., Stanhope J., M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2000
• Subjects: Helgoland; Hudson; North Atlantic
• Online Access: http://dx.doi.org/10.1046/j.1529-8817.1999.00001-135.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1529-8817.1999.00001-135.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1529-8817.1999.00001-135.x

The type species of Ceramium is Ceramium virgatum Roth (1797, Cat. Bot I: 148, pl. VIII, fig. 1). This has been treated as a probable synonym of Ceramium nodulosum (Lightfoot) Ducluzeau, one of the species formerly confused under the illegitimate name Ceramium rubrum (Hudson) C. Agardh. However, in 1996 Silva showed that C. nodulosum (Lightfoot) Ducluzeau is a later homonym of C. nodulosum de Candolle 1805, and advocated conserving C. rubrum with a neotype. As an alternative to this, we investigated whether the name C. virgatum might be available for this species. The lectotype of C. virgatum is Roth's illustration of a much‐branched, fully corticate, Ceramium specimen from Eckwarden, North Sea, which could represent any member of the ‘ C. rubrum’ group. We obtained material resembling Roth's, from the North Sea island of Helgoland, as a potential epitype. Its rbc L sequence was aligned with sequences of all C. rubrum ‐like species in the British Isles, i.e. C. secundatum , C. botryocarpum , C. pallidum and ‘ C. nodulosum ’. The Helgoland material was clearly conspecific with ‘ C. nodulosum ’ from Ireland (0.08% divergence). We therefore suggest that the name C. virgatum Roth should be employed for this species. Phylogenetic analyses of these sequences aligned with various representatives of the tribe Ceramieae, placed the North Atlantic C. rubrum ‐like species in two well‐supported clades. In one of these, C. virgatum is basal to C. secundatum and C. botryocarpum. The other clade consists of C. pallidum and a partly ecorticate species resembling C. diaphanum.