Udotea wilsonii A.Gepp, E.Gepp & M.Howe

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14. Udotea Wilsoni Gepp and Howe n. sp. A. & E. S. Gepp. Siboga Exped.
Monog. 62: 133.' '#'66-'6619ll.
Hab. Atlantic, Bahamas, Anguilla Isles, Salt Key Bank, North End, p.
Wilson. Howe no. 7968i
Plant about 10 cm. high, more or less calcified, stipitate* Stipes up
to 4 cm. (usually 1-1.5 cm.) long, simple or branched above, branches free or
cemented together.
Frond composed of a laminated mass of numerous flabellate prolifera-
tions arising from one another superfically, ana for the most part arising
from a position near and parallel to the central axis of the mass fi. e. an
imaginary prolongation of the stipes upwards). Individual fronds generally
semi-cordate at base, semi-rotundate above or semi-flabellate, entire or lobed,
striate, sometimes zonate, greyish-green with flavescent margins when young,
cinerascent when old. Surface very minutely spongiose or granulose.
Frond-filaments 40-50 u. in diameter, subparellel, mixed with flexuose
intricating branches, piuriseriate, sparingly dichotomous, without evident
supra-dichotomial constrictions, thickly beset with short, simple or forked,
very obtuse lateral appendages. Lateral appendages for the most part arranged
in two double rows directed towards the front and back surfaces of the frond,
about 25-40 u. long, in the upper part of frond; in the lower part of frond
less regular in arrangement and size, being usually distichously secund and
interrupted, about 25-120 u. long.
Filaments of stipes bearing lateral appendages one or more times
dichotomously divided and with obtuse apices. (Figs. 66-68).
Udotea Wilsoni is an interesting addition to the genus and forms with
its near ally, U. verticillosa, a group characterised by the crowded pseudo-
verticillose arrangement of the lateral appendages of, and by the absence of
supra-dichotomial constrictions from, the main filaments of the frond. The
most obvious difference between the two species is that the lateral append-
ages in U. Wilsoni are very obtuse (fig. 67), while in U. verticillosa they
are acute.
The specimens of U. Wilsoni submitted to us by Dr. Howe are all com-
piund (fig. 66), consisting not of a simple stipitate flabellum, but of a
laminated mass or a congeries of flabella hinged, as it were, upon an imagin-
ary axis forming an upward prolongation of the stipes. Possibly this pecuj-
ial habit may be due to the conditions under which these plants were found
growing. We have no data as to their environment, save that they were plenti-
ful in shallow, sandy bays (P. Wilson in Joum. New York Bot. Garden. X. 1909
p. 175).
We are indebted to Dr. Howe for permission to describe this species,
the material of which was communicated to him by Mr. P. Wilson the finder,
after whom it is named.
U. Wilsoni 18 at present only known from the Bahamas.
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