A REVIEW OF THE GENUS RHODYMENIA 

 WITH DESCRIPTIONS OF NEW SPECIES 



(Thirteen Plates) 

 Elmer Yale Dawson 



Department of Botany, University of California 



In attempting to determine the species of Rhodymenia collected on 

 the Allan Hancock Expedition of the Velero III to the Gulf of California 

 in January, 1940, it was found that the Rhodymenias of the Pacific Coast 

 of North America were very imperfectly known, specimens having been 

 referred to species such as Rhodymenia palmetta and R. corallina on little 

 more basis than a general resemblance in size and shape. In working over 

 the very considerable variety of specimens available in the Herbarium of 

 the University of California, it soon became clear that a review and re- 

 assembling of the species of the whole genus were necessary in order to 

 proceed with any certainty in the study of the species of the Gulf of 

 California. The following is a summary of the work as carried on thus 

 far, both in assigning described species to places in a systematic scheme 

 and in proposing new ones. 



Acknowledgment is due Dr. W. A. Setchell for his generous help 

 in the research and for preparing the Latin diagnoses of this paper; also 

 to Captain Allan Hancock and to Dr. T. Harper Goodspeed, through 

 whose expeditions material has been made available. 



The genus Rhodornenia was founded by Greville in 1830 and illus- 

 trated by a series of drawings of Rhodornenia palmetta (Greville, Alg. 

 Brit., 84, pi. XII (1830)). He apparently regarded R. palmetta as 

 typical of his genus, and we may consider it the type, although no actual 

 specimen was designated. Greville places some 10 species in his genus, 

 several of which are now segregated into other genera such as Gigartina, 

 Kallymenia, and Calliblepharis. Kuetzing (Sp. Alg., 778 (1849) in- 

 cluded Rhodornenia, Gracilaria, and the members of some other genera 

 under Sphaerococcus. 



J. G. Agardh reconstituted the genus (Sp. Alg. II, 375 (1851)), 

 revising the spelling to Rhodymenia as suggested by Montagne (Crj'^p. 

 Brasil., 42-55 (1839)). This spelling was adopted as preferred in 1912 

 in the International Rules of Botanical Nomenclature of the Congress 

 of Vienna (1905) and of Brussels (1910), and the generic name Pal- 



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