An Account of the Species of the Red Alga Polysiphonia of the Central 
and Western Tropical Pacific Ocean 
II. Polysiphonia 1 
George J. Hollenberg 2 
ABSTRACT: Seven polysiphonous species are described. Three species are new: 
Polysiphonia dotyi, P. pentamera, and P. tsudana . P. hoivei proves to be a very 
widely distributed species. P. exilis and P. tepida were previously known from the 
tropical Atlantic Ocean. P. homoia was previously known from the Pacific coast 
of Mexico. Of the polysiphonous species of Polysiphonia represented by the present 
study, none are corticated. 
key to the species (continued from Part I) 
2 6. Epizoic; erect branches 45-50p in diameter P. tsudana 
26. Not epizoic; erect branches lOOp or more in diameter 27 
27. With 5 pericentral cells 28 
27. With 7 or more pericentral cells 29 
28. Chiefly erect from a basal tuft of rhizoids; trichoblasts at intervals of 2-3 segments; seg- 
ments of main branches mostly 1.5 diameters long or longer P. homoia 
28. Chiefly prostrate or decumbent; trichoblasts at intervals of 5 or more segments; segments of 
main branches 1 diameter long or shorter P. pentamera 
29. Trichoblasts and scar-cells at infrequent intervals ; plants of estuaries and harbors ...... 
P. tepida 
29. Trichoblasts and scar-cells commonly one per segment 30 
30. Pericentral cells in longitudinal rows; wall-scars relatively prominent where trichoblasts shed 
11 P. exilis 
30. Pericentral cells in offset positions in successive mature segments 31 
31. Rhizoids cut off as separate cells from the distal end of the pericentral cells;' pericentral cells 
not tumid P. hoivei 
31. Rhizoids remaining in open connection with the pericentral cells; pericentral cells mostly 
tumid P. dotyi 
Polysiphonia dotyi sp. nov. 
Fig. 1 A, IB, 4, 5 
Chiefly prostrate or sometimes clambering 
algae; prostrate and erect branches mostly 140- 
1 Acknowledgments and designations used for col- 
lectors are given in Part I of this series (Pacific 
Science 22 ( 1 ): 56-98) . The material collected by 
C. R. Long, and reported in Parts I and II of this 
account, was collected under the auspices of the Pacific 
Ocean Biological Survey Program conducted by the 
Division of Birds, Smithsonian Institution. 
2 University of Redlands, Redlands, California. 
Manuscript received January 17, 1967. 
l60p in diameter; rhizoids unicellular with a 
broad open connection with the pericentral cells 
and with mostly discoid or occasionally multi- 
cellular apices; erect branches frequent, 0.5- 
1.0-(L0) mm high, with segments mostly 
shorter than broad and tumid, especially above; 
lateral branches few, arising in association with 
trichoblasts; pericentral cells mostly 8-10, 
ecorticate, arranged in offset positions in suc- 
cessive segments; trichoblasts one per segment 
with a right hand spiral turn of one pericentral 
cell between successive trichoblasts, mostly rudi- 
mentary but occasionally to 1.2 mm long, with 
198 
