Herposiphonia of Tropical Pacific — Hollenberg 
539 
Beach, Waikiki, Oahu, Dec. 26, 1964; an un- 
numbered collection by G. Trono, on S avgas sum 
sp., near the outer reef margin, Kaaawa, Oahu, 
Nov. 28, 1964; D. 19823.1, on Laurencia sp., 
Halena, Molokai, Dec. 28, 1953; marshall 
islands — H. 48-0914.19, on Pocockiella sp., 
on reef, Uku I., Bikini Atoll, July 9, 1948; 
CAROLINE ISLANDS — D. 2375 6.4, in algal turf, 
on reef, Quoi I., Truk group, legit Ernani 
Menez, Aug. 2, I960. 
This species seems closest to H. pecten-veneris 
Harvey (1853) as described by Taylor (I960), 
especially in the free-growing branches, with 
most of the indeterminate branches developing 
as lateral axes. It differs from Taylor’s descrip- 
tion in several respects: (1) somewhat more 
densely branched with less extensive free 
branches, and mostly shorter segments in the 
indeterminate branches; (2) mostly with one or 
more bare nodes between successive branches, 
seemingly not a feature of H. pecten-veneris ; 
(3) mostly more numerous and longer segments 
in the determinate branches, especially branches 
bearing mature cystocarps; (4) the apices of 
indeterminate branches strongly curved as in H. 
pecten-veneris, but the convex side morphologi- 
cally ventral rather than dorsal as described by 
Taylor. 
Herposiphonia crassa sp. nov. 
Figs. 12, 13 
Relatively coarse, densely branched algae, 
attached by numerous unicellular rhizoids, mostly 
with digitate tips, with 3 erect determinate 
branches between successive indeterminate 
branches and with no bare nodes ; prostrate 
branches 240-300p in diameter, with about 12 
pericentral cells and with segments mostly 
shorter than broad ; indeterminate lateral 
branches mostly remaining very short; deter- 
minate branches simple. Diameter, 100-140- 
(200) p, at the base and mostly narrower above, 
with a blunt apex, with 14-18 pericentral cells 
and composed of 8-9 segments, mostly about 1 
diameter long ; chromatophores not zonate ; 
trichoblasts 2-3, the first one formed mostly one 
segment from the apex, followed by 1 or often 
2, on reduced terminal segments, which are dis- 
placed slightly toward the distal end of the re- 
lated indeterminate branch; trichoblasts coarse, 
up to 1.7- (2. 4) mm long and 60jx in diameter 
at the base, with 6-7 forks and rounded apices 
10-1 Ip in diameter; young trichoblasts with an 
evident percurrent axis composed of 6-7 spheri- 
cal cells, with laterals in two longitudinal rows 
on the distal side relative to the related indeter- 
minate branch, the percurrent axis of the tricho- 
blast not evident at maturity ; tetrasporangia 
about 65p in diameter, in straight series of 4-6 
in the middle portion of determinate branches. 
Sexual plants unknown. 
Algae praecipue caespiticiae, tres ramos determin- 
ates erectos inter ramos indeterminatos successivos 
habentes; rami prostrati 240-300p diam.; rami de- 
terminati l40-200p diam. ad basim, manifeste an- 
gustiores supra, ex 8-9 segmentis plerumque aeque 
longis ac latis compositi; trichoblastae 2-3, grossae, 
prima in segmento infra apicem, deinde una duaeve 
in segmento terminali reducto, ad latus versus apicem 
rami fertilis summoto, orientibus; trichoblastae ad 2.4 
mm long.; 6-7 f ureas habentes; tetrasporangia 4-6 
continua in parte media ramorum nata. 
type collection: D. 22538, tetrasporic, 
abundant on boulders, Kahakuloa Bay, Maui, 
Hawaii, legit H., T., and B., April 21, 1965. 
This collection is represented by 3 glucose slide 
mounts and fluid-preserved material. 
ADDITIONAL COLLECTIONS EXAMINED: HA- 
WAIIAN ISLANDS — D. 8931.1, on Laurencia sp., 
on wave-swept rocks, Laie, Oahu, Oct. 27, 1951 ; 
D. 10385.1, tetrasporic, on C odium sp., at a 
depth of 5 ft, Kaaawa, Oahu, legit George 
Ikeda, Feb. 3, 1952; D. 17242.3, Halona, Oahu, 
legit Jessie Kajiwara, Nov. 14, 1956; D. 
17415.1, on Hypnea sp., Kukaimanini Rock, 
Oahu, Mar. 17, 1959; D. 20048.1, on Laurencia 
sp., wave-battered shore, Laie, Oahu, legit R. 
Tsuda, G. Trono, and R. Buggeln, May 5, 1963 ; 
H. 65-67, in algal turf, low littoral, Wawamalu 
Beach, Oahu, May 1, 1965 ; an unnumbered 
collection by M. Kajimura, Hanauma Bay, Oahu, 
Mar. 27, 1965; D. 22383.3, 22388, 22390, 
22398, all in algal turf, basalt shore 0.5 mile 
southwest of Maalaea, Maui, legit H., T., and 
B., Apr. 19, 1965; D. 22401.2, in algal turf, 
intertidal basalt shore, Papawai Point, north- 
west of Maalaea, Maui, legit H., T., and B., 
Apr. 21, 1965 ; D. 22410, 22410.6, in algal turf, 
near McGregor Point, Maui, legit H., T., and 
B., Apr. 19, 1965; D. 22533.2, tetrasporic, in 
