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 diam- 

 eters 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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