Rhodochorton coccineum K.M.Drew

• Region

  North America

• Country

  United States of America

• State/Province

  California

• County/Municipio

  San Francisco Co.

• Locality

  Fort Point

• Coordinates

  37.8106, -122.477

• Coordinate Uncertainty (m)

  264.569

• Georeferencing Method

  Georeferencing Quick Reference Guide, Version 2012. Located coordinates of geogr. center of Fort Point. Measured from coord. to farthest extent of the point to find linear extent (253 m). Input info. into MaNIS Georef. Calc. to find uncert. rad. (Bounded Area).

• Geodetic Datum

  WGS84

• Distribution

  Map all specimens of this taxon

NEW YORK

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285. Rhodochorton coccineum Drew

Fort Point, San Francisco, California.
Co-type.

Rhodochorton coccineum sp. nov.

Fig. 82. Cells of endophytie filament with parietal chromatophore but no
pyrenoid X 1600.

N. L. Gardner, No. 3488. Sept. 191G.

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PLATE 48

Rhodochorton coccineum sp. nov.

Fig. 83. Peculiarly shaped, endophytic filaments with vacuolate chromato-
phores. X 1600.

lig. 84. Diagrammatic representation of a transverse section of the blade
of Laminaria Sinclairii traversed by filaments of the endophyte which project
slightly on one side of the host. Approximately X 160.

Fig. 85. Part of such a section enlarged to show the endophytic filaments,
growing both between and in the cortical cells of the host, and the origin of
the branches which project beyond the surface of the host. X 1600.

Fig. 86. Free filaments with terminal tetrasporangia in various stages of
development. X 650.

Hhodoohorton coccineum Brew, sp.nov.

Univ.Galif.Publ.Bot.14;192. pl.4T^.f.82;pl.48.f.83-86.4 F 1928.

Plants endophytic; endophytic filaments present in all
tissues of the blade of the host, both inter-and intra-cell-
ular, irregularly branched, seldom branched in the medullary
tissues but often contorted and spirally twisted, much branch-
ed in the cortex, forming dense knots, especially in the
mucilage ducts, cortical layers completely occupied.ultimately,
by the parasite; branches usually originating near the center
of the cell; cells spherical, haustorial.cylindrical, or much
elongate, often bent and twisted and of very varying size, but
averaging around 4.0 p. diam.; chromatophore parietal but often
very diffuse and vacuolate, pyrenoid absent; endophytic fila-
ments ultimately growing beyond the surface of the host; free
part of the filaments short, consisting of 4-6 cells, very
rarely branched; cells cylindrical, decreasing in length but
increasing in width from base to apex, the average size at the
base being 6.0 p. by 15.0 p. and at the apex 10.0 p. by 7.0 p. ;
asexual reproduction by tetraspores; sporangia terminal, oval,

15.0 u wide and 22.0-24.0 p. long; spores arranged cruciately;
sexual reproduction and method of germination unknown.

ISndophytic in the blade of laminaria Sinclairii. Fort point,
San Francisco, and Duxbury Reef, Marin Gounty, California. January,
February (with tetraspores), March, September, October,November,
Type, Herb.Univ.CJalif.no.274015 (Gardner,no.3488). For tetraspores
see Herb. Univ.Galif. no.294545 (Gardner, no.3678).

This species may be very easily detected on account of the
bright red stripes it forms on the blade of the host, laminaria
Sinclairii. These stripes are often very long and vary from 2-10
mm. in width. Besides reinfection of the host by spores, some of
the endophytic filaments are perennial, like the host, and persist
in the old battered blades in the autumn, growing down into the
new blade as it is formed in January. Although it is very common
in Laminaria Sinclairii, at Fort point, throughout the year, the
tetrasporangia are very rare. The only tetrasporangia found were
on material collected in January. It is not at all uncommon, how-
ever, to find an occasional specimen of Laminaria Sinclairii with
a few filaments of R. coccineum protruding through the epidermis.

Judging from the way in which the filaments of Rhodochorton
coccineum invade the cells of the host and destroy the cell contents,
it seems to be a parasite. Although it does not visibly hinder the
development of the vegetative tissues, yet in some cases the sporangia
of the host do not develop over the infected areas, the fruiting zone,
in such a case having an irregular outline which runs parallel to the
edge of the red patches. Since this is not always the case, the age
at which the infection takes place probably determines the reaction
of the host. The endophytic filaments are often particularly numerous
in the mucilage ducts. There are two possible explanations of this.

It may be that the filaments, having more room, branch more, or that
the mucilage in the ducts is a source of nutritive
Rhodochorton.

UNIV. CALIF. F’UBL. BOT. VOL. 14