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232
ZYGNEMATACEAE
Usually the mature spores are ellipsoid, although ovoid spores
occur in most collections. The median wall may be smooth or
variously ornamented, and the color varies from pale yellow to
brown and black.
Twelve species are here described.
Key to the Species of SIROGONIUM
I. Zygospores with a smooth median wall 2
I. Zygospores with a variously ornamented median wall 4
I. Zygospore lenticular 12. S. p/iacosponim
2. Diameter vegetative cells usually less
than /J. 36 1. S. tenuius
2. Diameter vegetative cells usually between 36 and 56/^ 3
2. Diameter vegetative cells about 56-
66 /i 4. S. fiuridamnn
3. Diameter zygospores about 10-15 m
larger than vegetative cells 2. ^S. sticticiitn
3. Diameter zygospores 20-30 /a larger
than vegetative cells 3. 6\ megasporum
4. Median wall of zygospore single 5
4. Median wall of zygospore double... 10. S./iiti
5. Median spore wall "punctate" 6. 5. ceylaniciim
5. Median spore wall finely corrugate and
granulose 5. »S. pseiidofloridanum
5. Median spore wall brown to black, verrucose 6
5. Median spore wall reticulate g. 5. illinoicnse
5. Median spore wall scrobiculate \\. S. indicum
6, Diameter vegetative cells 65^2 /i. ... 7. ^S". ventersicujii
6. Diameter vegetative cells 70-90/i.... S. S.melanospunijyj
Descriptions or Species
I. SiROCONiUM TENUIUS (Nordstcdt) Transeau 1934. Ohio Jour.
Sci. 34, p. 420. Nordstedt. Bot. Notiser 1882. p. 47 (as
Spirogyra stictica var. tetiuior).
Vegetative cells 32-36^1 x 50-135 ;n; 2 to 5 chromatophores, nearly
straight; conjugation direct between shortened and more or less rcflexed
gametangia, separated by vegetative cells; receptive gamctangia intlatcd
to 60/i; zygospores ellipsoid varying to ovoid, 47-50 /t x 60-S8/1; median
spore wall yellow, smooth.
United States: Oklahoma; Texas; Arkansas; Florida.
Argentina, Cordoba; Brazil, Mate (irosso; Burma.