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CHAPTER TEN
THE GENUS TEMNOGAMETUM W. & G. S. WEST 1897
The vegetative cells and filaments of the species resemble those
of Mougeotia. The cells are cylindric, five to twenty-five diameters
long, each with a single axile platelike chromatophore. The
pyrenoids are arranged either several in a single row, or are
numerous and scattered. The cell sap in 2 of the species is purple.
The behavior during reproduction is very different from that
of the species of Mougeotia. The gametangia are short specialized
cells formed at the ends of scattered vegetative cells. They are
one to two diameters long and are gorged with starch and other
food substances. In scalariform conjugation the adherent sides of
two gametangia become distended and a hole develops within
the ring of contact. These connecting walls widen and become
the lateral walls of the quadrangular sporangium. Note that dis-
tinct conjugating tubes are not formed as in Mougeotia. In lateral
conjugation, two adjoining gametangia of the same filament
enlarge most at the separation wall, and the wall gradually dis-
appears. The gametes unite and the zygospore is obliquely
spindle-shaped. Aplanospores and parthenospores may be formed
from the reproductive cells. Only 4 species have been found—all
within the tropics.
Key to the Species of TEMNOGAMETUM
I. Chromatophores with pyrenoids in a row 2
I, Chromatophores with scattered pyre-
noids 4. T. thaxteri
2. Cell diameter io-12/x, zygospores
(lateral conjugation) 20-40 ju, x 40-
60 ju. I . T. tileanum
2. Cell diameter 14-17/A, zygospores
(lateral conjugation) 20-26 /a x 61-
67^0, 2, T. heterosporum
2. Cell diameter 14-20 /a, zygospores
(lateral conjugation) 35-42 /a x 80-
100 ju, 3. T. transeaui
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