Erythrocladia vagabunda M.Howe & Hoyt

Erythrocladia vagabunda sp. nov.

Endophytic or pseudo-epiphytic, creeping in the superficial cell
walls of other algae; thallus consisting chiefly of irregularly
branching, uniaxially elongate or irregularly radiating filaments,
finally spreading over areas 0.75-2.25 mm. long or broad, often
anastomosing or pseudo-anastomosing, and commonly forming
here and there small irregular pseudoparenchymatous patches
mostly 2-6 cells broad; ramification mostly lateral, rarely subdi-
chotomous, often divaricate or rectangular; cells (protoplasts)
for the most part irregularly oblong in surface view, often curved
or 1- or 2-lobed, 9-40 long, 6.5-15 ¿1 broad; pyrenoids 1-4 (usually
I or 2), 2-3 ,u broad; monoecious (?); sporocarps forming single
carpospores (rarely 2?), these ovoid, oblpng, or irregular, mostly
12-25 M in maximum diameter.; non-sexual spores unknown.
[Plate 12, figures 6—11; plate 13, figure 2.]

In the superficial cell walls of Dictyota dichotoma, dredged “in
i3K~I4 fathoms,” Lewis Radcliffe, August 11, 1914; associated
with Acrochaetium affine, Microchaete nana, Elachistea stellulata,
Sfcreblonema solitarium, Erythrocladia recóndita, etc.

Erythrocladia vagabunda is evidently a close ally of E. recóndita,
but appears to differ in its straggling, obviously filamentous
habit, in its more rectangular branching, in its forming pseudo-
parenchyma,- if at all, in small irregular scattered patches instead
of in a single central area, and in having cells of nearly twice the
average diameter of those of E. recóndita. It was our first im-
pression that it might be considered a variety of E. recóndita,
connected perhaps with its deep water habitat, but we finally
observed that it was associated, without ir^tergrading, with a
more minute, smaller-celled endophyte, the free filaments of which
radiate from a pseudoparenchymatous center. This smaller plant
we take to be the true E. recóndita, very slightly modified by its
deeper habitat. Wfien iodine is applied, the protoplasts of this
smaller plant take a darker blue-black or violpt-black color than
do those of the larger E. vagabunda. The two plants are shown
side by side and more or less intertangled in our photograph.

With the more ljmited material at oyr disposal, we have not
been able to demonstrate the sexuality of E. vagabunda so

116 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

factorily as in the case of E. recóndita, but from the general simi-
larity of the supposed carpogonia and sporocarps to those of
E. recóndita we feel no doubt as to its existence. In two instances,
we have seen a supposed spermatium resting on the general
surface above a supposed carpogonium. We have not observed
any carpogonium beak or trichogyne and think it must be only
slightly developed, if present at all.

The partly endophytic base of Acrochaetium affine, which some-
times develops short endophytic filaments or rhizoids, is occa-
sionally found in such close contact with Erythrocladia vagabunda
that it requires careful observation to satisfy one’s self that the
two things are not in organic continuity. The iodine stain, how-
ever, is an effective help in differentiating the two, the protoplasts
of the Acrochaetium reacting with a reddish brown rather than a
violet coloration.	__________________________

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2. Erythrocladia vagabunda. A photograph of the endophyte, made after staining
with iodine. Some of the larger cells are sporocarps. A small colony of E. recóndita,
staining more deeply and having smaller cells, is shown near B at the lower right-hand
corner, where it is more or less intertangled with the E. vagabunda. Enlarged 160
diameters.

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