Studies on the Green Alga, U do tea indie a A. & E. S. Gepp, 1911 
Mohammed Nizamuddin 1 
ABSTRACT: In Udotea indica reproductive organs are terminal and club-shaped. 
Numerous biflagellate zooids are produced in the reproductive organs. Udotea is 
named as the type of a new family, Udoteaceae. 
Udotea indica A. & E. S. Gepp (1911) was 
first collected by J. A. Murray (in 1880-83) 
from Karachi near the mouth of the Indus 
River. The type specimen is in the British Mu- 
seum and the type locality is Karachi. Previous 
taxonomic studies have been made, notably by 
Boergesen (1930, 1934) and Taylor ( 1950). 
This species has also been reported from Bikini 
and other areas in the Marshall Islands by Taylor 
(1950). It grows in association with Chaeto- 
morpha sp. on silt-covered rocks along the edges 
of littoral rocky pools, where it generally occurs 
in patches, but elsewhere it may be found scat- 
tered on rocky platforms. 
The genus has been included in the family 
Codiaceae by previous authors. The present 
study excludes Udotea from the Codiaceae and 
places it in a family of its own. The basis for 
this conclusion is that in Udotea indica the ter- 
minal portions of the filaments are transformed 
into reproductive organs, in contrast to the lat- 
eral position of the reproductive organs in the 
genera of the family Codiaceae. 
The discovery, made while examining living 
material, that the reproductive bodies are motile 
made a thorough investigation of this Udotea 
necessary. The present account gives the pre- 
liminary results of this study and, while not 
completely clarifying many features, shows that 
U. indica is not a member of the Codiaceae. 
The structure and reproduction of this species 
are discussed below. 
The thalli are up to 4 cm long, as much broad, 
and are slightly calcified. The root-mass forms 
a small tuft. The terete stipe is up to 1.2 cm 
1 Botany Department, University of Karachi, Ka- 
rachi, Pakistan. Manuscript received December 19, 
1961 . 
long and 1 mm thick. The fronds are green, 
somewhat rounded, flabellate, orbicular, and 
sometimes broadly proliferated above; the base 
is cuneate, distinctly zonate. The blade margins 
are entire, lobed, or lacerated. 
Filaments 31-48 [jl in diameter, radiating 
from the stipe to the margin, slightly parallel or 
interdigitated, pluriseriate to triseriate, dichoto- 
mously branched, supra-dichotomal constriction 
uneven. The filaments possess numerous uni- 
lateral or bilateral, short or pedicellate or trun- 
cate appendages that are simple or lobed. The 
appendages are so fitted together as to form a 
primitive cortex. The filaments of stipes are ir- 
regularly dichotomously branched, having lateral 
appendages (Fig. la-e) . Reproductive organs 
formed terminally on the filament (Fig. Id, e), 
each with a thick constriction in the middle, up 
to 16.2 mm long and 2.4 mm broad. 
The present effort is the first study made of 
reproduction in Udotea . The previous report on 
the presence of reproductive organs was con- 
sidered erroneous by Ernst (1904) and Fritsch 
(1956), who supposed the structures reported 
as reproductive to be epiphytes. 
The filaments are compact and interdigitated; 
but when fruiting occurs the terminal parts swell 
and separate, and cytoplasm passes into the swol- 
len parts, forming reproductive organs. The 
lower part of each serves as a stalk of the repro- 
ductive organ (Fig. le). The terminal portion 
of the fertile frond becomes loose, and as the 
filaments separate the reproductive organs show 
( Fig. 2 ) ; but in vegetative fronds the terminal 
edge of a blade is compact. 
Numerous zooids are produced and they are 
liberated successively through an apical pore. 
On liberation of the zooids the middle constric- 
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