Menez, Ernani G.2009-02-012009-02-011964-04Menez EG. 1964. The taxonomy of Polysiphonia in Hawaii. Pac Sci 18(2): 207-222.0030-8870http://hdl.handle.net/10125/5522An investigation of Polysiphonia collections from Oahu, Hawaii, Molokai, and Maui of the Hawaiian Islands has revealed the presence of seven species: Polysiphonia mollis Hook. & Harv., Polysiphonia pulvinata (Roth) J. Ag., Polysiphonia subtilissima Mont., Polysiphonia ferulacea Suhr., Polysiphonia yonakuniensis Segi, Polysiphonia flabellulata Harv., and Polysiphonia rhizoidea sp. nov. These seven species of Polysiphonia were recognized primarily by their morphological features. Some characteristics of Polysiphonia which have not been previously used by monographers but which appear to be important criteria for delimiting specific entities are discussed. One of these is the presence of more than one secondary pit connection between adjacent pericentral cells, a condition present in P. rhizoidea and P. yonakuniensis but not in the other 'species mentioned above. The other is the presence of multicellular rhizoids, a condition which was observed only in P. rhizoidea. Previously, authors have accepted the rhizoids of Polysiphonia as being unicellular.en-USArticle