Studies in the Helminthocladiaceae (Rhodophyta) : Helminthocladia 1 
Maxwell S. Doty 2 and Isabella A. Abbott 3 
During recent work in the field with the 
algae of Hawaii several interesting red algae 
have been found. Two of these interesting algae 
which seem to be members of the Helmintho- 
cladiaceae are reported here, in the hope that 
more work with such algae will be encouraged. 
The Helminthocladiaceae is accepted as be- 
ing a family, the limits of which would include 
eight genera that are rather well known and 
perhaps three genera that are not well known, 
Ardissonea, Dorella, and Endosira. Ardissonea 
was described by J. Agardh (1899: 99) and is 
treated by Kylin (1956: 127), under the name 
of Neoardis sonia Kylin, as a member of the 
Naccariaceae. Dorella , which may be a member 
of this family, has terminal cortical cells which 
are not enlarged. According to a personal com- 
munication from Dr. H. B. S. Womersley, the 
type of Ardissonea is a very finely branched 
alga and Endosira appears to be a juvenile of a 
different order. Kylin (1956: 557) suggests 
that Endosira may be related to Nemastoma. 
Consequently, we shall consider these genera 
no further in connection with the algae being 
described below. 
Of the eight easily recognizable genera, only 
Helminthocladia possesses lateral carpogonial 
branches and zygotes (post-fertilization carpo- 
gonia) which divide transversely, longitudinally, 
or obliquely and give rise to a dense gonimo- 
blast from both division products. In addition, 
1 The field and laboratory expenses for this work 
were provided in part by contract G-3833 between the 
University of Hawaii and the National Science Foun- 
dation, and by Graduate Research Funds of the Uni- 
versity of Hawaii. The authors appreciate the use of 
facilities at the Hopkins Marine Station of Stanford 
University for part of this work. 
Contribution No. 143 from the Hawaii Marine Lab- 
oratory. Manuscript received September 8, 1959- 
2 Department of Botany, University of Hawaii, Ho- 
nolulu 14, Hawaii. 
3 Hopkins Marine Station, Stanford University, Pa- 
cific Grove, California. 
in Helminthocladia the terminal vegetative cells 
in the cortex are strongly enlarged. Kylin (1956: 
108) uses this latter as a key characteristic to 
separate this genus from Helminthora. There 
are other differences between the two genera: In 
Helminthora, for example, only the upper cell 
of a transversely dividing zygote gives rise to 
gonimoblast filaments. Trichogloea differs from 
Helminthocladia and from other well-known 
genera in having straight terminal, rather than 
curved lateral, carpogonial branches and in its 
calcification. Dermonema has long been a rela- 
tively unknown genus but is distinct in form, 
being erect cushions formed of noncalcified 
closely dichotomous branches, sometimes like 
Chnoospora minima in looks and habitat. Both 
Dermonema and Cumagloia (Gardner, 1917: 
401) are distinct in having a diffuse gonimo- 
blast ramifying among the cortical filaments 
near the zygote from which it originated as a 
few protuberances with no previous division of 
the zygote. The genus Liagoropsis of Yamada 
(1944) is like Nemalion (Desikachary, 1957 a), 
having straight carpogonial branches, but differs 
in being calcified. 
On the basis of various characteristics the 
algae to be described are judged to be distinct, 
new species of Helminthocladia. They repre- 
sent the only records of this genus of the Rhod- 
ophyta for the Central Pacific Ocean. 
Helminthocladia simplex sp. nov. 
Figs. 1-18 
DESCRIPTIO TYPI: Thalli irregulariter cylin- 
drici, usque ad 9.5 cm. alt., acibus ramisque 
subsimplicibus saepissime 1 ad 1.5 mm. diam. 
Rami pauci, irregulariter dispositi. Thalli saepe 
simplices, qui saepe latiores quam thalli ramosi, 
raro, autem, plus quam 2 ad 4 mm. diam. Thalli 
simpliciores forma magis irregulares, clore 
magis obscuri, statura breviores saepe carpo- 
goniales sunt. Thalli antheridiales ubique vel 
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