Polysiphonia of the Tropical Pacific, I — Hollenberg 
83 
Aug. 1964; marshall islands — D. 92 15 A, 
and D. 9536.1, on a coral reef, transect area, 
Arno Atoll, legit Leonard Horwitz, July 30, 
1951; H. 48-Y58.3, on coral heads, Biijiri 1., 
Eniwetok Atoll, July 26, 1948; Caroline is- 
lands — D. 15586.1, on Padina sp. on a reef, 
Koror I., Palau Group, legit E. Menez, Sept. 5, 
I960; D. 21708.3, tetrasporic, reef flat, Epwel- 
kapw I., Ponape Group, legit E. Menez, June 
20, I960; PHILIPPINE ISLANDS — D. 18101 A, 
on a shell at a depth of 3-6 ft near Davao, 
Mindinao, legit E. Menez, June 22, 1958; 
viet nam — Da. 11218, tetrasporic, sperma- 
tangial, on rocks near a seawall, Nhatrang, 
Feb. 2, 1953; Indian ocean — David Sigee 29, 
lagoon reef flat, Gan I., Maidive Islands, July— 
Sept. 1964; pacific American mainland — 
variety villum is well represented in collections 
from southern California and from Pacific Cen- 
tral America; T. 1000 A, from tide pools on 
wave-washed basalt, Playa Coco, Guanacaste, 
Pacific Costa Rica, collected June 21, 1965, is 
representative of these collections ; Florida — 
Da. 7287, Da. 7289, tetrasporic, Da. 7293, 
Cutler near Miami, May 5, 1949; Da. 7314, 
tetrasporic, along a causeway, Biscayne Bay, 
Apr. 15, 1949. Bermuda — A. J. Bernatowicz 
53-358.1, intertidal turf, Bailey’s Bay, May 14, 
1953. 
A collection by Louis Williams, No. 910 
from Cape Lookout, N. Carolina, Aug. 1946, 
likewise seems representative of this variety. 
A minute variant form is H. 65-25.1, with few 
or no trichoblasts. Half embedded in a coral 
crust, this specimen was dredged from a depth 
of 2-3 fa in Kaneohe Bay, Oahu, Hawaii, 
Mar. 20, 1965. 
P. scopulorum var. macrotrichia var. nov. 
Fig. 1C 
Diminutive algae with creeping branches to 
70p in diameter, with segments 1. 5-2.0 diam- 
eters long, attached by occasional to frequent 
unicellular rhizoids which are not cut off from 
the pericentral cells as separate cells ; erect 
branches to 22 5 p high but mostly much shorter 
with segments mostly about 1 diameter long, 
arising endogenously at irregular intervals of 
about 8-10 segments; pericentral cells 4, ecorti- 
cate; trichoblasts one per segment in J spiral 
sequence on a few terminal segments of erect 
branches only, to 700p long with 6-7 dichot- 
omies and very delicate tips and with a basal 
cell to 170|x long and 20-28p in diameter, 
mostly soon deciduous leaving relatively promi- 
nent scar-cells and wall scars ; reproductive 
structures not observed. 
Algae diminutivae, proprietates speciei basicas prae- 
bentes, ramis repentibus, autem, relative amplis, ad 
70p. diam. et ramis erectis plerumque brevissimis, in- 
tervallis 8-10 segmentorum enascentibus, paucas tri- 
choblastas relative magnas ad 700p, long, ferentibus. 
type: D. 11514A1, collected by M. S. Doty 
and Jan Newhouse from a depth of 3-4 ft in 
a reef channel north of Oneroa, Raroia Atoll 
in the Tuamotu Archipelago, Aug. 5, 1952. 
It is represented by a glucose mount. 
ADDITIONAL collections: D. 21079-1, tetra- 
sporic, on other algae, Helen reef, Western 
Caroline Islands, legit E. Menez, Aug. 28, I960; 
D. 23112.4, on Microdictyon sp. on a reef on 
the eastern side of Ifaluk and Falalap Islands, 
Caroline Islands, legit E. Menez, Aug. 10, 
I960. The latter collection has the characteristic 
short erect branches from extensive creeping 
branches, but the trichoblasts are not large as in 
the type collection. More collections of this 
alga are needed to fully establish the distinc- 
tive features, especially reproductive features. 
It is interesting to note that a very similar 
alga was collected by Dr. Harold J. Humm. 
It was attached to B at op h or a, at a depth of 
1 5 ft, at Lower Matecumbe Key, Monroe 
County, Florida, Feb. 19, 1965. In most detailed 
features the Florida plant is close to the Raroia 
collection, differing chiefly in size. The diameter 
of the prostrate branches of the Florida speci- 
mens is more than twice as large as that of the 
Raroia plants, and the trichoblasts are about 
twice as long. However, this is in keeping with 
the generally diminutive nature of most Poly- 
siphonia species from the central Pacific. The 
Florida plants were likewise sterile. 
In its chiefly prostrate habit with very short 
erect branches P. scopulorum var. macrotrichia 
resembles P. anomala and P. delicatula, from 
which it differs chiefly in the rhizoids which 
remain in open connection with the pericentral 
cells. 
