Cultural evidence for the morphologic plasticity of Entophysalis deusta (Meneghini) Drouet and Daily (Chroococcales, Cyanophyceae)

Cultural experiments with Entophysalis deusta support Drouet and Daily’s concept of this species as a morphologically highly plastic taxon, showing forms traditionally identified as Entophysalis granulosa, Gloeocapsa crepidinum, Pleurocapsa fuliginosa, and Hyella caespitosa. These results are in accordance with observations on populations forming part of the ‘black zone’ of the upper intertidal belt. It is shown that Drouet and Daily’s taxonomic principles, leading to a broad and more natural concept of this species, are sounder than those underlying Geitler’s Cyanophyceae in which several entities included by them in Entophysalis deusta are treated as species.