Acrochaetium unifilum C. C. Jao

Acrochaetium unifilum, sp. nov.
(PL 10, figs. 26-32)	-
Thallo minutissimo, epiphytico; cellula basali singula subhemisphaerica,
filamenta erecta plerumque non ramosa, solitaria, rarissime bina, 1-9-cellula,
a facie laterali cellulae basalis emergente, plus minusve curvata, plerumque
ad hospitis superficiem parallela; cellulis vegetalivis plus minusve tumidis,
6.5-13/x latis, 13-16/i longis; pilis plerumque pseudolateralibus, interdum ter-
minalibus; chromatophoro slellari pyrenoideo centrali instructo; monospo-
rangiis sessilibus, rarissime pediculo unicellulo, unilateribus, interdum 2 in
cellulis singulis, ovatis, frequenter minoribus quam cellulis vegetalivis, 5-6.4//
latis, 8-9.6/i longis; monosporiis liberis globosis, circa 7/i latis; articulo primo
fili erecti exhibitum lateraliter a monospora germinate.
Plants very small, epiphytic, attached to the host by a single subhemi-
spherical basal cell, giving rise to a single unbranched, 1- to 9-cellecl and erect
filament from the lateral face, very rarely a second 1- to 3-celled short filament
also arises from the same basal cell; filaments more or less arched, generally
parallel to the surface of the host, about the same diameter throughout the
whole plant; vegetative cells more or less tumid in the middle, 6.5-13ju dia-
meter, 13-16/x long; hairs usually pseudolateral, sometimes terminal; chro-
matophore stellate, usually with four rays, with a central pyrenoid; mono-
sporangia sessile, very rarely with a 1-celled pedicel, unilateral, sometimes
two on each cell, oval in form, usually smaller than the vegetative cells, 5-6.4/i
diameter, 8-9.6/i long; free monospores globose, about 7/i in diameter; when
the monospore attaches to the host, it is gradually flattened on its attaching
side and becomes hemispherical; the first articulation of the erect filament is
laterally produced from the monospore and results in a single filament parallel
to the host plant; sexual reproduction unknown.
These new plants are probably near to Acrochaetium microscopicum
Naeg., but differ from it in having an unbranched erect filament arising
from the basal cell laterally, the vegetative cells not bead-shaped, the
hairs mostly pseudolateral and rarely terminal, and the monosporangia
mostly only half the diameter of the vegetative cells.
240	BULLETIN OF THE TORREY CLUB	[VOL. 63
Epiphytic on Arthrocladia villosa Duby, Norton Point, Marthas Vine-
yard, Massachusetts, Aug. 3, 1934. Type in C.-C. Jao collections and Herb.
Univ. Mich., Woods Hole No. 274.
Fig*-. 26~32-	IporTshowing IhTe"
sssur r¿.>..«> *.«. *. rr;
Zre Zl 30. a drvarf pla„t composed only ol a basal «11, a mo„osporan8,un. and a
£k ui m'no^pore freed from Ure ,„o„.sporangi™ just before drawn; b.ares 28-2»
and 31-32, adult plants in different forms.
02141546