Download PDF

154
ZYGNEMATACEAE
nation of dimensions, unilaterally inflated sporiferous cells, and the inflated
sterile cells. Has been found hybridizing with S. porttcalts, S. longata, and
S. communis and producing a variety of segregates. Due to the occurrence
of haploid segregates and the wide overlapping of cell and spore dimensions,
it has not been found advisable to separate the variants further.
13. Spirogyra bicalyptrata Czurda 1930. Beih. Bot. Zentralbl.
47, p. 31.
Vegetative cells 36-59^1 x 60-110/^, with plane end walls; chromatophore
i (rarely 2); conjugation scalariform; tubes formed by both
gametangia; fertile cells swollen on the conjugating side; zygospores
ellipsoid, 31-34/^ x 55-70 m; median spore wall brown, smooth, with
dark brown polar thickenings. (Pi. XXII, Fig. 2.)
Czechoslovakia; Austria; Greece.
Distinguished from S. varians by the occurrence of 2 chromatophores
in some cells and the brown polar thickening of the median wall. A similar
local polar thickening sometimes occurs in scattered spores of other species.
14. Spirogyra circumlineata Transeau 1914. Amer. Jour. Bot.
l,p.293.
Vegetative cells ( ^58-) 40-48 /x x 1 20-240 /m, with plane end walls;
I chromatophore, slender, making 4 to 8 turns; conjugation scalariform;
tubes formed by both gametangia; fertile cells inflated on the conju-
gating side only; zygospores ellipsoid, 40-50 m x 70-125 /x; median spore
wall yellow-brown, smooth; suture more or less prominent. (PI. XXII,
Fig- 3-)
United States: Iowa; Illinois; Michigan; Ohio.
Distinguished from S. varians by the larger dimensions, the slender
chromatophore making a larger number of turns, the distinct suture encir-
cling the spore, and the absence of inflated sterile cells.
15. Spirogyra supervarians Transeau 1934. Trans. Amer. Micros.
Soc. 53, p. 208.
Vegetative cells 50-57 /j. x 50-1 44 m;
i chromatophore; cells with
plane end walls; conjugation scalariform; tubes formed by both gam-
etangia; receptive gametangium inflated on the inner side; zygospores
ellipsoid, small in proportion to the gametangia, 35-40 m x 54-74 m;
median spore wall smooth, yellow. (PI. XXII, Fig. 7.)
Africa, Cape Flats (E. Stephens Coll.).
Similar to S. varians in appearance, but wiih much larger dimensions
throughout, and without inflated sterile cells.
16. Spirogyra fennica Ccdercreutz 1924. Acta Soc. pro Fauna et
Flora Fennica. 55 (2), p. 4.
Vegetative cells 15-19M x 60-260^, with plane end walls; i chro-