Herposiphonia of Tropical Pacific — Hollenberg 
555 
pericentral cells 10-12, around a central cell at 
least twice as broad, the pericentral cells some- 
what obliquely oriented; trichoblasts terminal, 
infrequent, mostly very rudimentary, with 1-3 
forks, occasionally as much as 1 mm long, soon 
deciduous; tetrasporangia about 65 p in diameter, 
in straight series of 3-4 or more in swollen 
segments of determinate branches borne on short 
indeterminate laterals, not in the determinate 
branches of main axes; sexual plants not ob- 
served. 
type locality: Enoshima, Boshu, Japan. 
A single collection, D. 12122T, tetrasporic, 
abundant on a branching coralline alga, was 
taken at Navuevu Cuvu, Singtoka, Viti Levu, 
Fiji Islands, Sept. 22, 1952. The specimens 
conform in general to Okamura’s description, 
including the presence of the usually very rudi- 
mentary trichoblasts. From Okamura’s descrip- 
tion the Fijian specimens differ in several re- 
spects: (1) they are probably more strictly 
distichous, with the determinate branches curving 
slightly toward the substratum; (2) the apices 
of indeterminate branches are slightly inrolled; 
(3) the tetrasporangia seem to be borne in the 
determinate branches of short lateral indetermi- 
nate branches, a feature not reported for H. 
subdisticha. Information concerning the sexual 
reproductive structures may be necessary to 
determine whether or not the Fijian alga is to be 
identified with the Japanese species. 
Dawson (1963:434) concluded that H. rigida 
Gardner (1927:100), H. rigida var. laxa Set- 
chell and Gardner (1930:164), and H. parva 
Hollenberg (1943:575) (H. pygmaea Hollen- 
berg, in Smith 1944:369) are all to be identified 
with H. subdisticha. Apparently Dawson failed 
to note that Okamura described the determinate 
branches of H. subdisticha as bearing "in its 
young state very short and minute deciduous 
fibrillae at the apex.’’ Examination of many 
specimens of distichous Herposiphonia from the 
coast of California has failed to reveal a single 
instance of trichoblasts on the determinate 
branches. Furthermore, the California specimens 
are strictly distichous rather than subdistichous, 
and the determinate branches are not narrowed 
at the base as in the case of the Fijian specimens. 
The position of the sexual reproductive struc- 
tures, when known, may provide further distinc- 
tions. Cystocarps of distichous specimens of 
Herposiphonia from California are borne toward 
the base of the determinate branches. 
It seems necessary to conclude that distichous 
Herposiphonia plants from California should 
not be referred to H. subdisticha. 
Herposiphonia tenella (C. Ag.) Schmitz 1889: 
449 
Hutchinsia tenella C. Agardh 1828:105 
Fig. 14 
Epiphytic algae, with prostrate indeterminate 
branches 8 0-9 Op in diameter, with about 8 peri- 
central cells, and composed of segments mostly 
1.0-1. 5 diameters long, bearing 3 erect determi- 
nate branches in alternating positions between 
successive indeterminate branches, with mostly 
no bare nodes; determinate branches up to 1.5 
mm high, 50-60p in diameter, composed of 
16-18 segments, mostly about 1.5 diameters 
long, with 8-9 pericentral cells ; chromatophores 
zonate; trichoblasts 2-5, in spiral sequence on 
the branches, the first one arising 2-8 segments 
from the ultimate apex, with 3-4 forks, mostly 
short, but occasionally up to 1.5 mm long; 
spermatangial stichidia (only one observed) 
190p long, 35p broad, cylindrical, with a one- 
celled short sterile tip, borne on the third seg- 
ment from the branch apex; procarps, cysto- 
carps, and tetrasporangia not observed. 
TYPE locality: On the coast of Sicily. 
COLLECTIONS STUDIED: HAWAIIAN ISLANDS — 
H. 65-33, H. 65-108.1, on other algae, dredged 
at 2-5 fa, Kaneohe Bay, Oahu, Mar. 20, 1965 ; 
PHILIPPINE ISLANDS — an unnumbered collection 
by D. P. Abbott, on other algae, Gnat Reef, 
Balabac I., Mar. 4, 1957 ; a collection by D. P. 
Abbott, on Halimeda sp., Pasig Bay, Balabac I., 
Mar. 3, 1957; a collection by Y. Kondo from a 
reef, Siasi I., northeast of Laminusa I., Jan 31, 
1957; MALDIVE ISLANDS — Ha. 24-2L-132-3B, 
on Pocockiella sp., on a reef at a depth of 4 ft, 
Walla Faru I., South Nilandu Atoll, Apr. 24, 
1964. 
Algae of the above collections are structurally 
in close agreement with the description of H. 
tenella given by Falkenberg (1901) in most 
respects. Falkenberg reports 20-50 segments in 
the determinate branches. The writer was privi- 
