Pleurocapsa epiphytica N.L.Gardner

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NEW YORK BOTANICAL GARDEN

DARIUS OGDEN MILLS FUND

FRESHWATER ALGAE OF PORTO RI(
COLLECTED BY PROFESSOR ijLWILLE
mayaguez February -g3-25-, 1915

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Pleurocapsa epiphytica sp. nov.

Plate 6, figure 59

Thallus very diminutive, 25-40 \i diam., 12-16 m (rarely 20 p)
thick; basal portion composed of angular cells, 3.5-5 m diam.,

without any definite radial arrangement, erect portion composed
of short, fairly definite, unbranched filaments with cells 2.8-3.2 n
diam., and about the same in length; gonidangia all terminal and
simple, 4.5-6 \i diam.; gonidia 1-1.5 m diam.

Growing on Cladophora sp. in a pool about four kilometers
north of Mayagiiez. The only specimen of the species is no.
1323 b, type.

This is the smallest species of the genus that has been pub-
lished. It has a very definite and characteristic method of de-
veloping the basal portion of the thallus. The gonidium divides
into two cells, after which each elongates and divides in the plane
perpendicular to the first, producing four cells of equal size.
An,y one or all of these four cells may divide, but usually the
plane of division is radial from the center of the four. After
this the dividing planes are usually in any direction perpendicu-
lar to the host, and the radial arrangement of the cells soon dis-
appears. Divisions of the cells in the center of the thallus by
¡»lanes horizontal to the host produce the erect series of cells,
in this case unbranched and each series composed of three to
five cells..

There is very little choice as to whether this species should be
placed in the genus Pleurocapsa or Radaisia.

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59

59. Pleurocapsa epiphytica

As seen in surface view in various stages of de-
velopment below the line and in section view
above the line............................................................................................. x 500

I^S'S	Determined by Francis Drouet and William A. Daily

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1.	Radaisia epiphytica Gardner, comb. nov.	! "

PUuroca„„ eliphytica Gardner, Mem. N. Y. Hot. Gard. 7: 31. s,	t*. S.* Ü , WrW.	b*U.

near Mayague^110^ ^°“r k^ometers ílorth of Mayaguez, 1823b. Type locality,	A/fr, 1»!	¿T'¡ - )D, » > l^| H

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