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32
ZYGNEMATACEAE
biculate; pits 4.5-6.5/1 in diameter and fi 2-7, apart, yellow-brown at
maturity. (PI. TV, Fig. 12.)
China, Szechwan.
41. Zygnema tholosporum Magnus & Wille 1884. Sydamerica
Algflora, p. 33, Pi. I, Figs. 49-52.
Vegetative cells 20 /x x 20-40//.; conjugation scalariform; zygospores
in one of the gametangia; receptive gametangia inflated; zygospores
globose, 36 /i in diameter; median spore wall brown, with numerous
circular prominences (umbonate). (PI. IV, Fig. 13.)
Uruguay, Montevideo.
42. Zygnema tenue Kiitzing 1849. Species Algarum, p. 445.
Vegetative cells 18-24 /t x 20-70 ju-; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia greatly enlarged
or inflated toward the middle; zygospores globose to ovoid, often somewhat
compressed, 25-30 /x x 25-40 as median spore wall brown, scrobic-
ulate; pits 2-3/A in diameter, 3-4/i. apart. (PI. IV, Figs. 14-15.)
United States: Illinois; Oklahoma.
Europe, widely reported; North and South Africa; China; Ceylon.
43. Zygnema leiospermum de Bary 1858. Untersuchungen iiber
die Familie der Conjugaten, p. 77, PL i, Figs. 7-14.
Vegetative cells 20-24/1 x 20-40/1; conjugation scalariform; zygo-
spores in one of the greatly enlarged or inflated gametangia; zygospores
globose to ovoid, 2^-30/1 x 23-32 /t; median spore wall brown, smooth;
aplanospores similar, but smaller in diameter.
United States: Minnesota and Illinois to the east coast.
Greenland; Iceland; British Isles; continental Europe.
44. Zygnema hausmannii (De Notaris) Czurda 1932. Siisswasser-
flora Mitteleuropa. 9, p. 121, Fig. 125.
Vegetative cells 21-23/1 x 34-72/1; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia enlarged mostly
on the inner side; zygospores globose or slightly compressed, 32-34/t x
28-34/1; median spore wall yellow-brown, pitted; pits 7-9/1 in diam-
eter; equatorial suture distinct. (PI. IV, Figs. 17-18.)
Austria; northern Italy; southern Australia.
45. Zygnema substellinum Taft 1934. Trans. Amer. Micros. Soc.
53, p. 212, PI, 17, Fig. 10.
Vegetative cells 22-24/1 x 50-70/1; conjugation scalariform; zygo-
spores in one of the gametangia; receptive gametangia greatly enlarged,
becoming nearly globose; zygospores globose, filling or nearly filling