Structure and Reproduction of Cottoniella hawaiiensis n. sp. 
(Rhodophyta ) 1 
Maxwell S. Doty and 
M. Ruth Wainwright 2 
While sorting over fine red algae washed 
onto the beach at Kailua, Oahu, Hawaiian 
Islands, the junior author discovered an alga 
which appears to be representative of a previ- 
ously undescribed specific taxon to be placed 
in the genus Cottoniella for reason of its obvi- 
ous similarities to Cottoniella arcuata Boerge- 
sen, the type of that genus. Accordingly, this 
newly found material is described here as: 
Cottoniella hawaiiensis n. sp. 
Figs. 1-9 
Thalli 2 cm. longi, ramis sterilibus poly- 
stichis ad 130 n diametro et a 4 cellulis peri- 
centralibus cinctis, cellula apicale 10-12 /jl 
diametro in serie segmentis discoideis trans- 
versalibus partita, segmentis deinde 4 cellulis 
pericentralibus ferrentibus, ramis endogenis a 
apicibus cellulis centralibus productis et eis 
stichidiis tetrasporangialibus vel ramis vege- 
tativalibus a ramo parenti simulantibus for- 
mantibus, ramis haplostichis determinatis ex 
angula ventrali anteriori cellulae lateralarum 
pericentralarum ferrentibus, stichidiis tetra- 
sporangialibus jugum sporangiarum tetra- 
hedro-partitarum ferrentibus, loculis sporangi- 
alibus ad 74 /x longa et ad 60 /jl diametro. 
The specimens were pale pink and, when 
disengaged from the other polysiphonous al- 
gae in which they were floating entangled, 
1 This work was supported in part by Faculty Re- 
search Committee funds of the University of Hawaii. 
Contribution No. 106 from the Hawaii Marine Labora- 
tory. Manuscript received June 10, 1957. 
2 Department of Botany, University of Hawaii. 
Honolulu, Hawaii. 
could be separated into lax unilateral branch 
systems up to about 2 centimeters tall (Fig. 1). 
The principle branches are up to 130 microns 
in diameter. The species is known only from 
the type collection (M. Doty No. 13,582) 
made November 13, 1955 by the junior au- 
thor. The type is deposited in the Bernice P. 
Bishop Museum with isotypes in the herbaria 
of the senior author, the New York Botanical 
Garden, the University of California (UCM- 
132664), and the University of Adelaide 
(21,100). 
It is to be noted (Figs. 2, 6) that the arching 
of the branches begins distad of the appear- 
ance of branch initials in C. hawaiiensis and 
appears to be correlated with elongations of 
the first pericentral cell produced. This char- 
acteristic of the branches is much like that fig- 
ured by Silva and Cleary (1954: 252, fig. 15) 
for Platysiphonia parva. 
The bases of the apical cells of the young 
endogenous branches, which are the only 
branches that become corticated, are about 10 
microns in diameter. The bases of the apical 
cells of the principle axes are often 12 microns 
in diameter. 
The discoidal segments cut off from the 
apical cells of the main branches elongate un- 
til they are at least one-third of their diameter 
in length (Figs. 2, 5, 6). They then produce 
abaxially first a dorsal pericentral cell (Figs. 
6, 7). At this time there are usually two dis- 
coid cells between that which bear this first 
pericentral cell and the apical cell. It appears 
that the pericentral cells to the right and left 
of the dorsal first pericentral cell are the next 
229 
