HOW TO KNOW THE FRESH-WATER ALGAE 



208a. (205) Chloroplasts without pyrenoids. Fig. 148 



MOUGEOTIOPSIS 



Fig. 148. Mougeotiopsis calospora 

 Palla. a, vegetative cells with plate- 

 like chloroplast (without pyrenoid); 

 b, zygospores. 



There is only 1 species of this 

 genus reported from the United 

 States, and it is very rare. It is pos- 

 sible to make tentative identification 

 of the species in the vegetative state 

 because the chloroplast is much like that of Mougeofia, but without 

 pyrenoids. The cells are characteristically very short cylindric. In 

 reproduction it is similar to Debarya (Fig. 149) in that the entire con- 

 tents of the conjugating cells become fused to form the zygospore. 



Figure 148 



208b Chloroplasts with 2 to several pyrenoids 



209 



209a Filaments slender, mostly under 12 li in diameter (rarely as much 

 as 30 [X or 42 jx): chloroplast a parietal plate, usually not filling 

 the cell; conjugating cells becoming filled with pectic substances; 

 granular residues not found in the emptied reproductive cells; 

 plants rare. Fig. 149 DEBARYA 



Fig. 149. Debarya sp., showing 

 formation of zygospores and the 

 lamellated substance deposited 

 in the conjugating cells. 

 Species of Debarya are like 



some of the slender species of 



Mougeotia and cannot be differ- 

 entiated in the vegetative condi- 

 tion. Debarya is much less frequently found than Mougeotia. In repro- 

 duction all of the contents of the conjugating cells enter into the forma- 

 tion of the zygospore and the space once occupied by the protoplasts 

 becomes filled with lamellated substance which is light refractive. 



Figure 149 



209b Filaments usually wider; chloroplast a broad, axial band with 

 conspicuous pyrenoids, filling the cell laterally (in most species) 

 but not in length; conjugating cells not filled with pectic sub- 

 stances; granular residues present in the emptied reproductive 

 ceUs; plants common. See Fig. 145 MOUGEOTIA 



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