Herposiphonia of Tropical Pacific — Hollenberg 
557 
to be a good key feature for distinguishing be- 
tween certain species, but it is an unreliable 
feature in this instance. 
Herposiphonia trichia sp. nov. 
Fig. 1 G 
Epiphytic algae, with prostrate branches about 
45 [X in diameter, attached by frequent rhizoids, 
and bearing 3 erect, slightly more slender, deter- 
minate branches 1-2 mm high, and composed of 
10-16 segments, arising in alternating positions 
between successive indeterminate branches or 
branch rudiments, with no bare nodes, or some- 
times with determinate and minute indetermi- 
nate branches at alternate nodes; pericentral 
cells 6-8 in indeterminate branches and lower 
parts of determinate branches, but occasionally 
reduced to 4 in the slender terminal parts of the 
latter; chromatophores not zonate; trichoblasts 
unbranched or occasionally with 1 or 2 laterals, 
up to 700 p long and about 8p in diameter at the 
base, composed of 8-9 cells, gradually tapering 
to a rounded or conical tip, arising one per seg- 
ment in 1/4 spiral sequence in the terminal parts 
of the determinate branches, mostly soon decidu- 
ous, leaving relatively large scar-cells; tetra- 
sporangia relatively large, 60-70jx in diameter, 
in straight series of 10-12-(l6) in the much- 
distended lower half of the determinate 
branches; spermatangial stichidia arising from 
the entire trichoblast primordium, without a 
sterile tip, 1 or 2 per branch on short unicellular 
pedicels, on the convex side of the branch, 3-5 
nodes from the base; procarps borne singly in 
similar positions ; cystocarps not observed. 
Algae epiphyticae, tres ramos determinates inter 
ramos indeterminatos successivos habentes, nodis nudis 
nullis; cellulae pericentrales plerumque 6 in ramis 
indeterminatis atque in partibus inferioribus ramorum 
determinatorum, in partibus terminalibus tenuibus, 
autem, ramorum determinatorum ad 4 reductae; trich- 
oblastae non ramosae aut interdum uno duobusve 
ramis lateralibus praediate, ad 700p, long., et c. 8p 
diam. ad basim, ex 8-9 cellulis compositae, ad ca- 
cumen rotundatum gradatim attenuatae; una in un- 
oquoque segmento spiraliter in partibus ramorum 
terminalibus orientes, plerumque mox deciduae, cel- 
lulas-cicatrices maiores reliquentes; tetrasporangia 
60-70p diam., 10-12 in serie recta in ramorum di- 
midio inferiore sita; stichidia spermatangialia e toto 
trichoblastae primordio, unum vel duo in unoquoque 
ramo determinato in latere convexo in nodo secundo 
ad quintum a basi posita, sine cacumine sterili; pro- 
carpi similiter orientes; cystocarpi non observati. 
type collection: D. 23461.1, tetrasporic, 
on Amphiroa sp., on a reef, Yap I., Caroline 
Islands, legit Ernani Menez, Aug. 18, I960. 
This collection is represented by two glucose 
slide mounts. 
ADDITIONAL COLLECTIONS EXAMINED: D. 
23466.1, spermatangial, on Amphiroa sp., along 
with the type collection; D. 23471.1, with pro- 
carps, on Amphiroa sp., from the same locality 
as the two preceding collections. This species 
resembles H. hollenhergii described by Dawson 
(1963:430) from the Pacific coast of Mexico. 
From that species it differs in the following 
respects: (1) decreasing size and number of 
pericentral cells in the upper parts of determi- 
nate branches, rather than increasing to 60-80p 
and to 10-12 pericentral cells in the upper parts 
of determinate branches as in the Mexican 
plants; (2) the pattern of development of 
secondary indeterminate branches; and (3) the 
much longer unbranched trichoblasts, which are 
described by Dawson for H. hollenhergii as 
"short, sparse or absent.” From H. deli cat ula 
the present species differs chiefly in the mostly 
unbranched trichoblasts. 
Herposiphonia variahilis sp. nov. 
Figs. IF, 2G, 17, 18, 21 
Saxicolous algae with prostrate branches 70- 
lOOp in diameter, with segments 0.7-1.0-(2.0) 
diameters long, with about 10 pericentral cells 
and with slightly inrolled apex, attached by fre- 
quent unicellular rhizoids ; erect determinate 
branches 0.3-1.0-(2.0) mm high at maturity, 
70-80p in diameter, composed of 10-l6-(50) 
or more segments 0.6-1. 5 diameters long, with 
8-10 pericentral cells and a central cell up to 
twice as large as the pericentral cells; only 1 
determinate branch between successive indeter- 
minate branches, each indeterminate branch 
being followed distally by (0)-l-6 bare nodes; 
indeterminate branches usually not extensive; 
chromatophores commonly zonate; trichoblasts 
3-4- (9) per erect branch, with only 2-3 
present at one time, the first-formed one as 
much as 10 segments from the ultimate branch 
apex; trichoblasts up to 2.5 mm long, with 4-6 
dichotomies and gradually narrowed to delicate 
tips, the basal cell frequently 200-350-(730)p 
long and 40-45-(58)p in diameter at maturity; 
