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PACIFIC SCIENCE, VoL XXII, January 1968 
sporangia about 65p in diameter in short spiral 
series in the ultimate branches; cystocarps glob- 
ular with a suggestion of a bracket-like base 
produced by an extension of the short pedicel; 
spermatangial branches arising as a primary 
branch of a trichoblast. 
Algae epiphyticae ad 8 mm alt., e penicillo basali 
rhizoideorum saccatorum rubrorum ad 125p long, 
quae hospitem penetrant et ut cellulae discretae a 
cellulis pericentralibus separantur, enascentes; rami 
erecti 75-100p diam., ramos laterales intervallis 
plerumque 5—10 segmentorum qui sine coniunctione 
trichoblastis enascent, habentes; cellulae pericentrales 
4, ecorticae, segmentis aeque longis ac latis aut 
longioribus; trichoblastae ad 680p long., 2-4 dicho- 
tomias, una in unoquoque segmento in I spira in ramis 
erectis, habentes; cellulae-cicatrices in ramis et erectis 
et prostratis; tetrasporangia in serie brevi spirali in 
ramis ultimis innata; cystocarpi globosi; rami sperma- 
tangiales ut ramus primarius trichoblastae enascentes. 
type: D. 18740D, tetrasporic, cystocarpic 
and spermatangial, epiphytic on a species of 
Codium awash at Midway L, after a severe 
storm, and collected by C. H. Lamoureux, Dec. 
16, 1962. It is represented by fluid-preserved 
material and several glucose microslide mounts. 
It is the only collection of this species. 
The rhizoids of this alga are confusingly 
similar to those of P. saccorhiza, which was 
growing on the same host. From that species 
it differs in the chiefly erect habit in contrast 
to the chiefly prostrate habit of P. saccorhiza. 
Also the erect branches are much higher and 
branched, whereas the erect branches of P. sac- 
corhiza are rarely if ever branched. 
It may be that this is the same alga to which 
Cribb (1956:135) refers, when he mentions a 
"different Polysiphonia on Codium ” with both 
inflated and non-inflated rhizoids. Along with 
the two Midway algae with inflated rhizoids 
were several specimens of a separate plant with 
non-inflated and non-pigmented rhizoids, which 
seem to be best identified with P. savatieri 
Hariot. 
Polysiphonia saccorhiza (Collins and Hervey) 
comb. nov. 
Lophosiphonia saccorhiza Collins and Hervey 
(1917:127) 
Figs. AC, 4D 
Epiphytic algae with prostrate branches 50- 
70p in diameter and with segments 1.0-1. 3- 
(2-|-) diameters long, attached by unicellular 
rhizoids cut off by a cross-wall from the center 
of the pericentral cells ; rhizoids soon becoming 
prominently saccate, to l40p in diameter in the 
saccate tips and to 500p long, deeply pink with 
numerous discoid chromatophores about Ip in 
diameter distributed around the periphery of 
the cell ; all branches are prostrate or tend soon 
to become more or less prostrate except for the 
short erect reproductive branches, and all mor- 
phologically prostrate branches bear the saccate 
rhizoids, although many of the rhizoids do not 
penetrate the host tissue; branches arising endog- 
enously and at intervals of mostly 6-12 seg- 
ments; erect reproductive branches are up to 
5 5 Op high and about 40p in diameter with seg- 
ments 1. 5-2.0 diameters long. They bear tricho- 
blasts on upper parts, one per segment, which 
are mostly not well developed but are occasion- 
ally to 300p long with 2 dichotomies; tricho- 
blasts are soon shed, leaving scar-cells one per 
segment in J spiral sequence and often prom- 
inent wall-scars at the point of abscission ; scar- 
cells infrequent on strictly prostrate branches; 
tetrasporangia 40-5 Op in diameter, in short 
series in the erect branches, much distending the 
narrow segments; cystocarps 1-2 near branch 
tips, mature pericarps subglobular, to 21 Op in 
diameter and 240p long with cells well sepa- 
rated and tending to occur in transverse as well 
as longitudinal rows ; spermatangial branches 
arising as a primary branch of a trichoblast. 
A single collection D. 18739 A, tetrasporic, 
cystocarpic, and male, epiphytic on Codium sp., 
was made by C. H. Lamoureux, Midway I., 
Dec. 16, 1962. 
The Midway plants differ from the orig- 
inal description of the Bermuda plants in minor 
respects : ( 1 ) the erect branches are much 
shorter and are not noticeably contracted at the 
base; (2) the trichoblasts are not well devel- 
oped; (3) the rhizoids usually do not penetrate 
the host, but are abundant on the preponderantly 
prostrate branches, or potentially prostrate lat- 
erals; (4) the rhizoids are somewhat smaller; 
(5) the cystocarps are larger (probably a matter 
of maturity). 
Since these specimens of P. saccorhiza were 
found on the same host as was P. ruhrorhiza, 
and since the two entities have very similar 
saccate and pigmented rhizoids, the question 
