Polysiphonia of the Tropical Pacific, I — Hollenberg 
85 
P. sco pulorum var. minima var. nov. 
Figs. 6G, 7B, 34 
Minute algae with creeping branches 40-50p 
in diameter, with segments mostly shorter than 
broad, attached by unicellular rhizoids which 
are not cut off from the pericentral cells as 
separate cells and which commonly have digitate 
tips; erect branches 200-3Q0p (to 1 mm) high 
and 35-40p in diameter, unbranched or oc- 
casionally branched near the base, arising 
endogenously at frequent but irregular intervals, 
with segments mostly about 1 diameter long; 
trichoblasts commonly relatively large (to 7 5 Op 
with basal cell to 200p long and 28p in diam- 
eter), with 4-6 dichotomies, arising at irregular 
intervals on median parts and often one per 
segment in spiral sequence in upper parts of 
erect branches, soon shed; scar-cells not present 
in prostrate branches; tetrasporangia 35-40p 
in diameter, somewhat protuberant, in straight 
or slightly spiralling short series in the erect 
branches; cystocarps globular to ovoid, to 130p 
in diameter, with cells of the ostiolar rim not 
enlarged; spermatangial branches oblong 115- 
145 X 40-4 5p, with a small sterile terminal 
cell and a stipe mostly 3 5-5 Op long but occa- 
sionally to 180p long, arising from the entire 
trichoblast primordium. 
Algae minutae proprietates speciei generales prae- 
bentes, minores, autem, maxima ex parte, ramis pro- 
stratis 40- 5 Op diam. et ramis erectis ad 1 mm alt., 
intervallis satis crebris endogene enascentibus, et 
trichoblastas relative magnas ad 750p long., quae 4-6 
dichotomias habent, ferentes; rami spermatangiales in 
stipitibus longioribus binatim producti. 
type: H. 65-113.4, tetrasporic, cystocarpic 
and male, consists of three glucose slides and 
fluid-preserved material. It was collected by 
R. S. Jones at a depth of 1-2 m, about 20 m 
shoreward from the outer reef margin north of 
North L, Johnston I., Apr. 22, 1965. It was 
growing on dead coral. 
additional collections: D. 11859-2, ster- 
ile, on encrusting corallines, sea reef near 
Otetou, Raroia, Tuamotu Archipelago, collected 
by M. S. Doty and Jan Newhouse, Aug. 21, 
1952; D. 23112.7, tetrasporic, on Halimeda, 
on reef at eastern side of Ifaluk I., Caroline 
Islands, collected by E. G. Menez, Aug. 10, 
I960. 
In the short segments this variety is similar to 
var. scopulorum, but it is a much smaller plant 
and more delicate and, unlike var. scopulorum, 
the spermatangial branches have a terminal 
sterile cell and at least sometimes long stipes 
(Fig. 7 B). They may occur in pairs, as in P. 
scopulorum. This instance in which the stipe 
of the spermatangial branch was 180p long may 
not be representative of the variety. 
Polysiphonia setacea sp. nov. 
Figs. 5 A, 5 B, 5C 
Chiefly saxicolous algae, relatively setaceous, 
commonly forming extensive patches to 1 cm 
high from prostrate branches attached by 
rhizoids, which are at first unicellular and cut 
off as separate cells mostly from the distal end 
of the pericentral cells, but at maturity mostly 
develop multicellular tips : erect branches to 
1 cm high, arising mostly cicatrigenously, mostly 
unbranched, composed of segments 65-70- 
(100)p in diameter and 0.7-1.5-(2.0) diam- 
eters long with walls relatively thick (5-8pi); 
pericentral cells 4, ecorticate; trichoblasts rela- 
tively coarse, with l-(3) dichotomies, mostly 
much reduced and quickly deciduous; scar-cells 
in upper parts one per segment in J spiral 
sequence but mostly at intervals of 2-3 segments 
below, and at intervals of 1-3 segments on pros- 
trate branches ; pericentral cells in erect branches 
commonly slightly oblique rather than in 
straight longitudinal rows ; tetrasporangia in 
slightly spiral series, up to 30 in the series, in 
terminal parts of erect branches; somewhat dis- 
tending the segments; sexual plants unknown. 
upper portion of erect branch. 14, Polysiphonia hancockii, tip of erect branch. 15, Polysiphonia poko, tip 
of erect branch with spermatangial stichidia. 16, Polysiphonia hawaiiensis, with cystocarps. 17, Polysiphonia 
beaudettii, with fruiting lateral branches. 18, Polysiphonia profunda, tip of erect branch showing origin of 
lateral branch in association with a trichoblast (from the type slide). 19, Polysiphonia subtilissima, tips of 
erect branches. 20, Polysiphonia profunda, tip of erect branch, with young cystocarp and persistent tricho- 
blasts. 21, Polysiphonia sphaerocarpa var. sphaerocarpa, a slender form with tetrasporic branches narrowed at 
the base. 
