Polysiphonia of the Tropical Pacific, I — Hollenberg 
69 
off Ewa Beach, Oahu, Feb. 22, 1962 ; D. 
19143R1, on other algae, dredged 31-32 fa, 
Penguin Bank, southwest of Molokai, Sept. 7, 
1959; line islands — D 20041, on mollusc 
shell, seaward reef flat, Christmas I., legit Ralph 
E. Palumbo, May 16, 1962; tuamotu ar- 
chipelago— D. 11189-3, on dead coral, D. 
11857.6, D. 11858.2, D. 11860C, all from 
lagoon transect, Otetou, Raroia Atoll, legit 
M. S. Doty and Jan Newhouse, Aug. 21, 1952; 
marshall islands — D 95 86 A, rock scrapings, 
D 9599E, on Udotea sp., D. 9599GA, on Lau- 
ren cid sp., D. 9693B, on Halimeda sp., all on 
lagoon reef off Ine Village, Ine I., Amo Atoll, 
legit Leonard Horwitz, Aug. 17, 1951; H. 48- 
0914.15, on Microdictyon sp. ; H. 48-0914.22, 
on Dictyosphaeria sp., H. 48—1091.13, on Po- 
cockiella, outer reef, Arji L, Bikini Atoll, 
July 12, 1948 (probably all of these should be 
identified with this species although in some 
the segments are frequently more than one di- 
ameter long in both prostrate and erect branches, 
and rhizoids arise mostly at the proximal end 
of the pericentral cells) ; Caroline islands — 
D. 159893, on other algae, Helen Reef area, 
legit E. Menez, Aug. 28, i960. 
D„ 11858.2 from sea reef near Otetou, 
Raroia Atoll, Tuamotu Archipelago, represents 
a variation in which the erect branches are up 
to 7 mm high with more laterals and with seg- 
ments about 1 diameter long. A variant, H. 
48-1091T3 from the outer reef of Arji L, 
Bikini Atoll, in the Marshall Islands has pros- 
trate branches only 90p in diameter and seg- 
ments to 1.6 diameters long. 
Polysiphonia mollis Hooker and Harvey 
For synonomy see Hollenberg (1961:359), 
also P. aquamara Abbott (1947:212). 
Fig. 43 
Plants to 8 cm high, assurgent from limited 
prostrate portions attached by unicellular rhi- 
zoids, with or without lobed tips, cut off mostly 
from the proximal end of the pericentral cells 
by a cross-wall; 4 pericentral cells, ecorticate, 
with segments 1. 5-3.0 diameters long in the 
main branches and with segments somewhat 
nodose at the ends ; median parts of erect 
branches 120-1 30«x in diameter; branching 
pseudodichotomous and corymbose, with 
branches of many orders arising exogenously 
in place of, and not in connection with, tricho- 
blasts, with mostly 6-8 segments between suc- 
cessive branches; branches gradually narrowed 
toward the base; trichoblasts one per segment 
in regular J spiral sequence, commonly 100- 
280|x long with 1-3 forks, but often poorly 
developed, soon deciduous, leaving scar-cells of 
moderate size ; basal cell commonly considerably 
shorter than cells next above ; tetrasporangia 
60-80p in diameter in slightly or prominently 
spiral series in the ultimate ramuli; cystocarps 
ovoid to globular up to 300ji in diameter; 
spermatangial branches measuring 140-2 / Op X 
60-7 5 fx, arising mostly as a primary fork of a 
trichoblast but sometimes as a secondary fork 
and sometimes bearing a short or longer sterile 
tip of 2-4 cells. 
Mostly plants of relatively quiet water, and 
often of brackish water. 
type locality: Tasmania. 
COLLECTIONS STUDIED: HAWAIIAN ISLANDS 
— D. 9765B, tetrasporic, cystocarpic, Sand I., 
Honolulu, Oahu, Jan. 27, 1956; D. 12386, 
12389, from a pond-connecting channel, Coco- 
nut L, Oahu, Feb. 5, 1954; D. 12684, D. 12689, 
tetrasporic, cystocarpic, spermatangial, Keehi 
Lagoon, airport side of Mokuaea I., Oahu, 
Dec. 30, 1954; D. 12792, mudflats in front of 
Kuliouou Beach Park, Oahu, June 10, 1955; 
D. 13356, on Natatorium floats, Waikiki, Oahu, 
Oct. 2, 1956; M. 704, tetrasporic, on Acan- 
thophora , near old sugar mill, windward Oahu, 
July 7, 1961; M. 725, 739, tetrasporic, on 
concrete blocks under and near a seaward bridge, 
Ala Moana Park, Oahu, May 5, 1961; M. 758, 
759, tetrasporic, cystocarpic, muddy area at 
Keehi Lagoon, Oahu, Feb. 27, 1961; I. Abbott 
1535, tetrasporic, cystocarpic and spermatangial, 
as P. aquamara, legit C. J. Engard, Kuapa Pond, 
Oahu, Apr. 7, 1944; I. Abbott, as Polysiphonia 
aquamara spermatangial, "Salt Lake,” Oahu, 
July 2, 1945; Tahiti — Setchell 5213 (C. 
261338), as P. tongatensis Harvey, legit W. A. 
Setchell and H. E. Parks, Port Phaeton, June 24, 
1922; Philippine islands — a collection by 
D. P. Abbott, Siasi L, Jan. 28, 1957, a smaller 
and more slender form probably to be identi- 
fied as P. mollis var. tongatensis (Harvey) 
comb, nov., is frequently found in sheltered 
