Comment:The authourship of C. verticillatus is (Lightfoot) C. Agardh 1817 in Womersley. This combination is based on Conferva verticillatus Schmidel 1794 a later homonym of Conferva verticillatus Lightfoot 1777. This means the Cl. verticillatus (Lightfoot) Agardh is a nomen nudum and Cl. verticillatus (Lightfoot) Lyngbye is a valid name. Although Prud'homme van Reine 1972 Blumea XX:142 wished to separate C. verticillatus and C. spongiosus as forms of C. spongiosus Womersley does not follow this. Silva et al 1996 Univ Calif Public Bot. 79:574 does do so.