Polysiphonia of Tropical Pacific — Hollenberg 
203 
cystocarpic, on Gracilaria, 20-55 fa, Explosive 
Ammunition Area, Oahu, July 24, 1959; D. 
19118A1, on Cnoospora sp. 16-25 fa, Pokai 
Bay, Oahu, Aug. 1, 1959; D. 19134D1, on 
other algae, 25 fa, outside channel buoy, Ka- 
neohe Bay, Oahu, July 25, 1959; D. 19135Z1, 
spermatangial, on Hypnea sp., 26 fa, Waialua, 
Oahu, Aug. 2, 1959; D. 19136F3, cystocarpic, 
15 fa, Waialua, Oahu, Aug. 2, 1959; D. 
19143T1, cystocarpic, on Liagora sp., 15 fa, 
Ilio Point, Molokai, Sept. 7, 1959. 
This alga seems to be a plant of deeper 
water. It compares favorably in most respects 
with the description of the type and previously 
the only known collection of this plant. It 
differs in two respects: (1) the tetrasporangia 
are reported as occurring in straight series in 
the type material, and (2) the type is de- 
scribed as having a short sterile tip on the sper- 
matangial branches. 
Polysiphonia howei Hollenberg, in Taylor 
1945:302; Hollenberg 1958:64. 
P. rhizoidea Menez 1964:217, P. yonakunien- 
sis Menez 1964:219, P. yonakuniensis 
Segi 1951:257, Lophosiphonia obscura 
Weber v. Bosse (1923) not of Falkenberg 
1901:500 
Figs. ID, 1 E, 2 A 
Plants forming low dense mats on rocks, up 
to 1.5 cm high and to 7 cm or more in diam- 
eter; prostrate branches 100-170p in diameter 
attached by unicellular rhizoids, with digitate 
to multicellular tips, often several per segment, 
each cut off by a cross-wall from the distal end 
of the pericentral cell; erect branches 100-1 50p 
in diameter, arising exogenously at the tips of 
prostrate branches, or sometimes cicatrigenously, 
at intervals of 6-8 or more segments, at first 
strongly curved toward the apex of the prostrate 
branch, and bearing frequent, mostly curved, 
lateral branches; prostrate branches giving rise 
ventro-laterally to prostrate lateral branches in 
alternating positions on either side mostly 2 
segments distal from each erect branch; 8-10 
pericentral cells around a relatively large central 
cell, the pericentral cells, beginning 8 or more 
segments from the branch tip, shifting to offset 
; positions, so that each pericentral cell is in con- 
tact at either end with 2 pericentral cells of the 
adjacent segment, with each of which it soon 
develops 1, or sometimes 2, secondary pit con- 
nections; segments in prostrate and erect 
branches mostly less than 1 diameter long; 
trichoblasts relatively coarse, to 600p long and 
28p in diameter at the base, with short basal 
cells, even at maturity, and with about 4 dichot- 
omies, not diminishing greatly toward the 
rounded tips, arising at no regular intervals but 
frequently, one per segment in I/4 spiral se- 
quence, at least in upper parts; tetrasporangia 
45-5 5 p in diameter, in spiral series in the ulti- 
mate branches, not distending the segments; 
cystocarps ovoid, 175-200-(360)p in diameter; 
spermatangial branches near branch tips 120- 
170p long and 3 5-5 Op in diameter on a sturdy 
1 -celled stalk, without a sterile tip, arising from 
the entire trichoblast primordium or frequently 
one from each primary branch of the trichoblast. 
type locality: Berry I., Bahamas. 
MATERIAL examined includes the following: 
HAWAIIAN ISLANDS — D. 846 1, 8462, tetra- 
sporic, Kaneohe Bay, Oahu, Nov. 24, 1950; D. 
10816, Kapoho Point, Kailua, Oahu, Oct. 10, 
1953; Josephine E. Tilden 602, tetrasporic, 
Faie Point, Oahu, June, 1900 (as P. calothrix 
Harvey); D. 13448, 13458B, tetrasporic, on 
basalt ledge, west lip of Pohoiki Bay, Island of 
Hawaii, legit M. S. Doty and A. J. Bernatowicz, 
Nov. 10, 1956; D. 13076, Anaehoomalu, 
Island of Hawaii, legit Amy Sollenwell, Nov. 
15, 1952; D. 17220A, Punaluu Bay, Island of 
Hawaii, Jan. 29, 1953; D. 17304, low mats on 
lava, Laupahoehoe Point, Island of Hawaii, 
Jan. 28, 1953; D. 19256, tetrasporic, sperma- 
tangial on prehistoric lava flow dike, east of 
1955 flow, 6-8 inches above high tide level, 
Keekee, Island of Hawaii, Dec. 23, 1959; D. 
19354, in shaded crevices of 1955 lava flow, 
Keekee, Island of Hawaii, Sept. 8, I960; D. 
19359, King’s Landing, Panaewa, Island of Ha- 
waii, Sept. 13, I960; American Samoa — T. 
701-704, on intertidal basalt, mouth of 
Fagasa Bay, Tutuila I., Aug. 21, 1964; T. 
682, on a log above high tide level, Afono, 
Tutuila I., Aug. 22, 1964; Philippine is- 
lands — D. 16198, above low tide, western 
shore of Cuenco I., Hundred Islands, Pan- 
gasinan Prov., legit M.S. Doty and E. Menez, 
Feb. 15, 1958; D. 18077B, tetrasporic, cysto- 
carpic, south of Sasa wharf, Davao, legit E. 
