22 ZYGNEMATACEAE 



REPRODUCTION BY APLANOSPORES 



53. Aplanospores blue 54 



53. Aplanospores or akinetes yellow to brown 55 



54. Spores punctate with irregular elon- 

 gate pits (S7. Z. borzae 



54. Spores scrobiculate, diameter vege- 

 tative cells 21-23 M 80. Z. jrigidum 



54. Spores scrobiculate, diameter vege- 

 tative cells 33M 85. Z. hypnosporum 



54. Spores smooth 84. Z. quadrangitlatum 



55. Diameter vegetative cells less than 25 /a 56 



55, Diameter vegetative cells 26 to 36 /i. 57 



55. Diameter vegetative cells greater than 36 ^ 58 



56. Vegetative cell diameter 1 5-1 8 m, 



spores dolioform 94. Z. mlrificum 



56. Vegetative cell diameter 16-21 /i., 



spores ovoid 81. Z. spontanettm 



56. Vegetative cell diameter 17-20M, 



spores cylindric 86. Z. schwabei 



56. Vegetative cell diameter 20-22 ft, 



spores ellipsoid 93- -^- ellipsoideum 



57. Median spore wall scrobiculate 82. Z.cylindricum 



57. Median spore wall granulose 88. Z. subcylindricum 



57, Median spore wall pitted 95- ■^- khannae 



58. Diameter vegetative cells 40-42 /x, 



spore cylindric 89. Z. irregulare 



58. Diameter vegetative cells 44-54 m, 



akinetes 83. Z. sterile 



The following species have been found in some collections produc- 

 ing both zygospores and aplanospores: Z. catenatum, Z. circumcari- 

 natum, Z. collinsiantim, Z. cruciatum, Z. excrassttm, Z. jantcum, 

 Z. giganteum, Z. insigne, Z. leiospermum, Z. neocru datum, Z. pecti- 

 natum, Z. peliosporum, Z. stellinum, Z. terrestre, and Z. synadelphum. 



Descriptions of Species 



I. Zygnema oveidanum Transcau 1934. Trans. Amer. Micros. 



Soc. 53, p. 208, PI. 17, Fig. I. 



Vegetative cells 8-12 ^ x (32-) 35-40 (-68) m; conjugation scalariform; 



zygospores formed in the conjugating tubes, ovoid to globose, 12-15/1 x 



15-30 ju; median spore wall colorless to yellow, punctate; pits about lu 



in diameter. (PI. II, Fig. 3.) 



