92 
PACIFIC SCIENCE, Vol. XXII, January 1968 
Puna district, Hawaii, Mar. 21, 1965; H. 65- 
12.5, cystocarpic, on other algae, Kapoho, Ha- 
waii, legit John Fitzsimons, Mar. 1, 1965. 
Polysiphonia suhtilissima Montagne (1840:199) 
Fig. 19 
Plants to 4 cm high, from prostrate branches 
attached by relatively long, unicellular rhizoids, 
often with lobed tips, which remain in open 
connection with the pericentral cells; erect 
branches 70-1 30p in diameter in median parts, 
with lateral branches arising independent of 
trichoblasts at intervals of 5-8- (14) segments, 
and with frequent endogenous branches arising 
from prostrate branches; segments in the main 
branches mostly 1.0-1. 5 diameters long; peri- 
central cells 4, ecorticate; cell walls mostly thin 
and hyaline, except in lower parts where they 
may be considerably thickened, to lip; apical 
cells relatively large ; trichoblasts infrequent and 
usually poorly developed and unbranched but 
occasionally to 400p long, with 1-2 dichot- 
omies, tapering to delicate tips, but relatively 
straight and stiff, soon deciduous leaving incon- 
spicuous scar-cells; reproductive structures not 
observed in the materials studied. 
Although usually sterile and smaller than the 
species elsewhere, Pacific specimens correspond 
closely to the features generally attributed to the 
species, except that the rhizoids although mostly 
long are not particularly coarse as described by 
Taylor (I960) for the species in Atlantic waters. 
Found mostly in slightly brackish water. 
type locality: Cayenne, French Guiana, 
northern South America. All but one of the 
collections identified with this species are from 
the island of Oahu, Hawaii. This probably in- 
dicates a lack of collections from suitable locali- 
ties elsewhere. 
P. suhtilissima var. suhtilissima 
COLLECTIONS STUDIED: M. 710, 711 (BISH), 
at a depth of 4.3 ft, along the bank of Waipuhi 
stream, Kamehameha Highway bridge, near 
Kaneohe, Feb. 24, 1961; M. 727, 728A (bish), 
from basalt rock wall, Waipuhi stream near 
Hauula School, Feb. 24, 1961 ; D. 14695, on 
rocks, south end of Salt Lake, Honolulu, Hawaii, 
early Jan. 1964; C. 696325, legit Cyril Cross- 
land 6721, Marquesas Islands, 1923-24. 
P. suhtilissima var. abbottae var. nov. 
Figs. 5 F, 6A 
With the features of the species but with 
longer segments (2—2.5 diameters long) in 
median parts of the main branches, with more 
slender main branches (50-70p in diameter), 
and with abundant and relatively persistent 
slender trichoblasts to 600p long and 6-9p in 
diameter at the base, composed of relatively 
long cells, arising at intervals of 2-3-(12) 
segments; reproductive structures unknown. 
Varietas proprietates speciei habeas, segmentis, 
autem, longioribus (2. 0-2. 5 plo longioribus quam 
lata) in ramis principalibus qui tenuiores (50-70p 
diam) et trichoblastas tenues abundantes relative per- 
sistantes, ad 600|a long., 6-9p. diam ad basim habent; 
trichoblastae e cellulis relative longis, intervallis 2-3- 
(12) segmentorum enascentibus compositae; structurae 
reproductivae ignotae. 
The type and only known collection of this 
variety was collected from the shores of Salt 
Lake, Oahu, and reported by Isabella A. Abbott, 
No. 1757. The water in this pond was described 
by Abbott (1947) as nearly fresh. Abbott gave 
two figures (13 A, B), but did not assign the 
plant to a definite species on account of the 
lack of reproductive structures. The habitat and 
the nature of the rhizoids strongly suggest 
placement in P. suhtilissima . The most distinc- 
tive feature of the variety is the abundance of j 
trichoblasts. Rhizoids remain in open connec- 
tion with the pericentral cells and tend to arise 
in more or less whorled arrangement (Fig. 6A). 
P. suhtilissima Segi (1951:197) cannot be 
identified with Montagne’s species if the Ha- 
waiian specimens and the specimens from the 
southeast coast of the United States mainland 
are properly identified. Segi’s Figure 8A shows 
rhizoids cut off as separate cells, a feature indi- 
cative of another species. 
Polysiphonia tenuis sp. nov. 
Figs. 6B, 6C 
Minute algae with creeping branches 3 0-3 5 p 
in diameter, composed of segments about 1 
diameter long and attached by unicellular 
rhizoids, which are cut off from the pericentral 
cells as separate cells; without scar-cells on the 
prostrate branches ; erect branches to 2 mm high, 
unbranched, 28-3 5 p in diameter, with segments j 
mostly 1.5- (2.0) diameters long, arising endog- 
