Polysiphonia of the Tropical Pacific, I — Hollenberg 
87 
the west lip of Pohoiki Bay, Puna, Island of 
Hawaii, Nov. 10, 1956. 
Characteristic features of this low matted 
species are: the rhizoids with multicellular tips 
arising at the distal end of the pericentral cells, 
and the more or less oblique position of the 
pericentral cells, which are periclinally flattened. 
Polysiphonia spars a (Setchell) comb. nov. 
Lophosiphonia sparsa Setchell (1926:103) 
Figs. 5 D, 23, 40 
Epiphytic algae to 1 cm high from prostrate 
branches attached by relatively large unicellular 
rhizoids cut off by a cross-wall from the proxi- 
mal end of the pericentral cells and often with 
finely digitate tips; plants relatively stiff, with 
4 ecorticate pericentral cells and with segments 
mostly 0.2-0. 5 diameter long and 2Q0-280p 
in diameter in median parts of main branches; 
trichoblasts one per segment in J spiral se- 
quence ; usually poorly developed but sometimes 
to 650p long with 3-5 dichotomies and up to 
9 cells in length of longest axis, with very 
delicate tips, soon deciduous, leaving small scar- 
cells and often prominent wall scars; branches 
arising independent of trichoblasts, with mostly 
7-12 segments between successive branches; 
tips of branches acutely pointed; leading axes 
commonly distinct, the branching mostly not 
at all dichotomous, at least near apices; tetra- 
sporangia 8 0-8 5 p in diameter, spiralling in the 
ultimate and subultimate branches and even- 
tually distending the segments somewhat; cysto- 
carps to 330p in diameter, nearly spherical, 
with very short, broad attachment and pericarp 
of relatively large cells 30-40p in diameter; 
spermatangial branches arising as a primary 
branch of a trichoblast without sterile tip. 
COLLECTIONS STUDIED: HAWAIIAN ISLANDS — ■ 
D. 19144Q3, D. 19145 AF, dredged 6-13 fa 
and 40-85 fa respectively, Port Allen, Kauai, 
Sept. 12, 1959; an unnumbered collection by 
G. F. Papenfuss, from near the Elks Club, 
Waikiki, Oahu, Apr. 1, 1942; society islands 
— D. 12104, tetrasporic, among and attached to 
turf-forming corallines, near Arue Pt., Arue, 
Tahiti, Nov. 15, 1952; D. 14693, legit J. 
Randall, on corallines, reef flat, Matavai Bay, 
Tahiti, Apr. 2, 1956; phoenix islands — O. 
Degener 24866A, tetrasporic, Canton Atoll, 
Feb. 18, 1958; L. 2434.8, McKean I., Oct. 19, 
1964; marshall islands — D. 9536H, scraped 
from a flat rock near the edge of the reef, 
transect area Arno Atoll, legit Leonard Horwitz, 
Aug. 10, 1951; H. 48-0290.4, inner reef, Eric 
I., Bikini Atoll, July 13, 1948; H. 48-1091.16, 
outer reef, Arji I., Bikini Atoll, July 12, 1948; 
H. 48-1213.1, tetrasporic, Amen I., Bikini 
Atoll, Aug. 7, 1948; H. 48-2894.7, on other 
algae, Nama I., Bikini Atoll, July 15, 1948; 
Philippine islands — two unnumbered collec- 
tions by D. P. Abbott, 1957: Laa Tawitawi, 
Sulu Sea, Feb. 12; south end of Gnat Reef, 
Balabac I., Sulu Sea, Mar. 4, 1957. 
Examination of the type of Lophosiphonia 
sparsa Setchell, kindly loaned from the her- 
barium of the University of California at Berke- 
ley, leads the writer to conclude that the 
specimens listed above are to be identified with 
this species, which for reasons presented in 
the introductory paragraphs of this paper is 
more properly placed in the genus Polysiphonia. 
It seems likely that specimens of this species 
have been sometimes identified as P. ferulacea. 
However, P. sparsa is a much smaller plant 
with much shorter segments especially in termi- 
nal branches, and has spermatangial branches 
without the sterile tips, seemingly characteristic 
of P. ferulacea. 
Polysiphonia sphaerocarpa Boergesen (1918: 
271) 
P. pulvinata Menez (1964:215) — P. pulvi- 
nata Segi (1951:195) non Conferva 
pulvinata Roth (1797:187), non P. pul- 
vinata Kiitzing (1863:12), non P. 
pulvinata (C. Agardh) J. G. Agardh 
Intertidal tufted algae mostly 0.5-1. 5 cm high 
from prostrate branches of limited extent (80)- 
100-200p in diameter, attached by unicellular 
rhizoids, which are cut off as separate cells 
from the pericentral cells; erect branches assur- 
gent to cicatrigenous, mostly 100-1 8 Op in diam- 
eter, with segments mostly 1.0-1. 5 diameters 
long, pseudodichotomously branched in a some- 
what flabellate manner; branches arising inde- 
pendent of trichoblasts, at intervals of 7-11 
segments; pericentral cells 4, ecorticate; tricho- 
blasts one per segment in J spiral sequence, 
1 00-200- (5 80 )p long with mostly 3-4 dichot- 
