Observations on Cystoseira squarrosa De Notaris (Fucophyceae, Fucales), a rare and little known Mediterranean species, and its typification

A study of the morphology of the brown alga Cystoseira squarrosa De Notaris, a rare and little known species, was carried out on numerous thalli collected at Torre del Serpe near Otranto (Apulia, Italy). Because the original material of this species, held in the Herbarium of the University of Genova (GE), was destroyed during the Second World War, a neotype is designed here. The species is well characterized by the combination of the following characters: not caespitose, bush-like habit; short primary axis bearing 1-2 secondary axes inserted at right angle; oblong and warty tophules; slightly prominent and smooth apex of the axes; robust, rigid, flattened, not spaced spinose appendages with bifid, trifid or multifid apices and conceptacles grouped at the base of the spinose appendages.