74 
PACIFIC SCIENCE, Vol. XXII, January 1968 
tulum urceolati, ad 150jr lat. et paululo longiores; 
rami spermatangiales lit ramus primarius trichoblastae 
probabi liter enascentes. 
type: H. 65-52, tetrasporic, cystocarpic and 
spermatangial, growing on dead coral at a depth 
of 1-2 m, and 20 m shoreward from the outer 
reef margin, north of North I., Johnston L, 
legit R. S. Jones, Apr. 22, 1965. It is repre- 
sented by fluid preserved material and 6—8 
glucose microslide mounts. 
additional collection: T. 1393, sperma- 
tangial, on top of a coral head at a depth of 
about 1 ft northeast of North I., Johnston 
I., Nov. 18, 1965. 
The minute size and chiefly prostrate habit 
are features characteristic of P. scopulorum var. 
villum, but the rhizoids of P. pseudovillum are 
cut off as separate cells. Also the erect branches 
arise cicatrigenously in P. pseudovillum but 
endogenously in P. scopulorum var. villum. 
Polysiphonia quadrata sp. nov. 
P. coacta Tsuda (1964:11) not of Tseng 
(1944:71) 
Fig. 25 
Plants to 8 mm high, assurgent from creep- 
ing branches attached at frequent intervals by 
unicellular rhizoids which are cut off as separate 
cells from the proximal end of the pericentral 
cells and may have digitate tips ; creeping 
branches l60-180p in diameter, composed of 
segments 0.3-0. 5 diameters long; assurgent 
erect branches 100— l60p in diameter, with 
segments mostly about 0.5 diameter long and 
gradually very short near the tapering apices; 
branches infrequent, replacing trichoblasts ; peri- 
central cells 4, ecorticate, mostly quadrate in 
external view, walls brownish and 8-1 Op thick 
in older parts; trichoblasts arising at irreg- 
ular intervals of 4-8 or more segments, very 
rudimentary with 2-3 dichotomies, quickly de- 
ciduous, leaving relatively small scar-cells ; re- 
productive structures unknown. 
Plantae ad 8 mm alt., a ramis repentibus assur- 
gentes, affixae intervallis frequentibus per rhizoidea 
unicellularia quae ut cellulas discretas ab extremo 
proximali cellularum pericentralium separata et cacu- 
mina digitata interdum habent; rami repentes 160- 
180p diam., e segmentis 0.3-0. 5 plo brevioribus quam 
lata compositi; rami erecti assurgentes 100-l60p, 
diam., segmentis plerumque ca. 0.5 brevioribus quam 
lata necnon brevissimis prope apices attenuatos grada- 
tim factis; rami infrequentes, pro trichoblastis sub- 
stitute cellulae pericentrales 4, ecorticatae, externe 
visae plerumque quadratae, parietes brunneolos, in 
partibus vetustioribus 8-1 Op crass, habentes; tricho- 
blastae intervallis irregularibus 4-8 vel plurim seg- 
mentorum enascentes, multum elementariae, 2-3 di- 
chotomias habentes, cito deciduae, cellulas-cicatrices 
relative parvas relinquentis; structurae reproductivae 
ignotae. 
TYPE: D. 18774, collected by N. J. Cooper 
from below low water line on a reef just south 
of Rawanawi Village on the Marakei Atoll, 
Gilbert Islands, July, 1962. 
additional collection: D. 18921.1, like- 
wise sterile, was collected by the same person 
from the same general area, at a depth of 20- 
30 ft in a deep surge channel, July, 1962. 
This species is very similar to a species with 
5 pericentral cells to be described in Part II 
of this study. It differs, furthermore, in having 
mostly shorter segments in mature parts. The 
cells of P. quadrata plasmolyze readily in 20% 
glucose, due probably to the thinness of the 
walls of the relatively large pericentral cells of 
younger branches. 
Polysiphonia rubrorhiza sp. nov. 
Figs. AA, AB, 32 
Epiphytic algae to 8 mm high initially at- 
tached by a tuft of rhizoids from a basal cell 
and adjacent pericentral cells, later attached by 
additional rhizoids arising from prostrate stolon- 
like branches of limited extent emerging from 
the basal segments of primary erect branches; 
rhizoids to 125p long, enlarged saccate to 11 Op 
in diameter, thin-walled, deeply pink with nu- 
merous peripheral chromatophores about 3p in 
diameter, arising as separate cells cut off from 
the pericentral cells and penetrating among the 
utricles of the host; pericentral cells 4, ecorti- 
cate, with segments as long as broad or slightly 
longer; erect branches 75-1 OOp in diameter in 
the median parts, either endogenous or cicatri- 
genous in origin, pseudodichotomously branched 
above at intervals of (2)— 5— 10 segments, the 
branches arising independent of the trichoblasts ; 
trichoblasts to 680p long, with 2-4 dichotomies, 
arising one per segment in J spiral sequence 
in erect branches, and quickly deciduous; scar- 
cells on both erect and prostrate branches; tetra- 
