558 
PACIFIC SCIENCE, Vol. XXII, October 1968 
trichoblasts with about ^3 spiral divergence, at 
intervals of 1-5 segments, soon deciduous, leav- 
ing large scar-cells and commonly prominent 
wall-scars; tetrasporangia 40-50p in diameter, 
in straight series of (6) -13-24, in terminal 
parts of the branches; cystocarps subterminal, 
3 5 Op in diameter, ovate, with a prominent 
ostiolar beak ; spermatangial stichidia slightly 
lanceolate, l60-200p long and 6 0-6 5 p in di- 
ameter, on a short 1 -celled pedicel, and with a 
short 1 -celled sterile apex, arising terminally 
from the entire trichoblast primordium. 
Algae saxicolae ramos prostratos ad lOOjii diam. 
qui ramos determinates erectos 0. 5-1.0- (2.0) mm alt. 
et 70— 80|Lt in diam., e 7-15-(30) segmentis 0.6-1. 5 
plo longioribus quam latis composites, ferunt, cellulis 
pericentralibus 8-10, habentes; 1-5 nodi nudi inter 
ramos indeterminatos successivos plerumque semper 
breves, unicum ramum consequentes; chromatophora 
vulgo zonata; trichoblastae 3-4- ( 9 ) in unoquoque 
ramo erecto, 2-3 semel, trichoblasta primum formata 
usque ad segmentum decimum ab apice rami sita; 
trichoblastae usque ad 2.5 mm long., 4-6 dichotomias 
habentes, ad cacumina tennuia gradatim attenuatae, 
intervallis 1-3 segmentis spiraliter ordinatae, mox 
deciduae, magnas cellulas-cicatrices reliquentes; tetra- 
sporangia 40-50p diam., in partibus ramorum ter- 
minalibus sita; cystocarpi subterminales, c. 3 5 Op 
diam., ovati, rostro ostiolari conspicuo praediti; sti- 
chidia spermatangialia sublanceolata, l60-2Q0p long., 
60-6 5p diam., apicem sterilem unicellularem bre- 
vemque habentia, in parte extrema ramorum deter- 
minatorum orientia, e primordio toto trichoblastae 
formata. 
type collection: H. 65-113, tetrasporic, 
cystocarpic, spermatangial, on dead coral at a 
depth of 1-2 m and 20 m shoreward from the 
outer reef margin north of North I., Johnston 
Island, legit R. S. Jones, April 22, 1965. This 
collection is represented by 7 glucose slide 
mounts and additional fluid-preserved material. 
ADDITIONAL COLLECTIONS EXAMINED: HA- 
WAIIAN ISLANDS — D. 22533.1, in algal turf, 
near Honokohau, Maui, legit H., T., and B., 
April 20, 1965; JOHNSTON ISLAND — T. 1068, 
1069 A, on dead coral, legit R. Buggeln and Earl 
Murchison, Aug. 17, 1965; T. 1351.1, tetra- 
sporic, on dead coral, at a depth of 3.3 m, north- 
east of North I., inside of wave-break zone, legit 
R. Tsuda and R. Buggeln, Nov. 18, 1965 ; line 
islands — L. 2705.3, tetrasporic, with unusually 
long determinate branches, in surge channel of 
reef flat, Jarvis I., Nov. 16, 1964; D. 20029, 
northeast point of Christmas I., legit Ralph 
Palumbo, June 3, 1962; tuamotu archi- 
pelago — D. 11160.6, on dead coral, coral reef 
near passageway, Raroia Atoll, legit M. S. Doty 
and Jan Newhouse, July 9, 1952; marshall 
islands — H. 48-0914.30, tetrasporic, outer reef, 
EJku I., Bikini Atoll, July 9, 1948. 
This is a very variable species as to number of 
bare nodes, degree of development and number 
of trichoblasts, and the number of segments in 
the determinate branches. As many as 75 were 
counted in L. 2705.3. In some instances the 
large number of segments seems to be due to 
renewed growth of the branch. Determinate 
branches occasionally develop one or more lat- 
erals which may be either determinate or in- 
determinate. Although procarps arise subtermi- 
nally, mature cystocarps may be as much as 10 
segments from the branch apex, as a result of 
continued growth of the branch. 
H. variabilis is probably closest to H. tenella 
form secunda, from which it differs chiefly in 
the following respects: (1) the greater vari- 
ability in the number of segments in the deter- 
minate branches (Falkenberg [1901] reports 
14-20 segments for the European specimens 
examined) ; (2) the great length of the tricho- 
blasts in some specimens; and (3) the more 
numerous tetrasporangia in many cases. 
REFERENCES 
Agardh, C. A. 1824. Systema Algarum. Lund, 
xxxviii -f- 312 pp. 
1828. Species Algarum 2(l):i-lxxvi 
+ 189 pp. Gryphiae. 
Boergesen, F. 1915-1920. The marine algae 
of the Danish West Indies. III. Rhodophy- 
ceae. Dansk Bot. Arkiv. 3(1) : 1-504. 
Dawson, E. Y. 1956. Some marine algae of the 
southern Marshall Islands. Pacific Sci. 10(1) : 
25-66. 
1963. Marine red algae of Pacific 
Mexico 8. Ceramiales: Dasyaceae, Rhodo- 
melaceae. Nova Hedwigia 6:401-481. 
Falkenberg, P. 1901. Die Rhodomelaceen des 
Golfes von Neapel. Fauna und Flora des 
Golfes von Neapel, Monograph 26. Berlin, 
vii + 754 pp. 
