ZYGNEMA 19 



21. Vegetative cell diameter ^y-Tpii 28. Z. ma jus 



21. Vegetative cell diameter 32-38 ju. 29, Z. I^iangsiense 



22. Zygospores blue, carinate, and 



punctate 35- •^- carinatum 



22. Zygospores yellow to brown 23 



23. Diameter vegetative cells 14-20/i 24 



23. Diameter vegetative cells 20^1 or more 25 



24. Spores 15-25/^ X 25-35 /x, all walls 



smooth 30. Z. raljsii 



24. Spores 28-32 /J. X 36-40//., median 



wall punctate 3i- -^- micropunctatum 



25. Median spore wall smooth, brown 32. Z, momoniense 



25. Median spore wall pitted, yellow-brown 33. Z. circumcarinatum 

 25. Median spore wall double, outer layer 



smooth, inner verrucose 34- -^^ pawhus\ae 



SPORES IN THE GAMETANGIA 



26. Median spore wall colorless, yellow, or brown 27 



26. Median spore wall blue 45 



27. Diameter vegetative cells less than 20 /t 28 



27. Diameter vegetative cells 20-30 /i 29 



27. Diameter vegetative cells more than 30 /a 40 



28. Vegetative cell diameter 9-12/^, 



spore wall punctate 36- Z. stagnale 



28. Vegetative cell diameter 14-20 m, 



spore wall punctate 37- -2^- subtile 



28. Vegetative cell diameter 15-18 /a, 



spore wall punctate 38- ■^- cylindrospermum 



28. Vegetative cell diameter 16-18 ju-, 



spore wall with pits 3-4.5 f. 39- ■^- yunnanense 



29. Median spore wall smooth 30 



29. Median spore wall punctate to scrobiculate 31 



29. Median spore wall verrucose 39 



30. Diameter vegetative cells 20-24 /x.. 43. Z.leiospermum 

 30. Diameter vegetative cells 26-30 ju,.. 55. Z.insigne 



31. Pits 2/x or less in diameter 32 



31. Pits more than 2 /a in diameter 33 



32. Diameter vegetative cells 22-29^, 



pits widely spaced 46. Z. luteosporum 



32. Diameter vegetative cells 23-26 /x, 



pits closely spaced 48. Z. calosporum 



