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82 ZYGNEMATACEAE
2^^i in thickness. In a few species with quadrangular spores,
pectose layers arc formed between the sporangium wall and the
spore. Most species have yellow to brown spores; 8 species have
blue spores.
Only during the reproductive phases of the life cycle can
species of Debarya and Temfiogametum be separated with cer-
tainty from those of Moitgeotia.
Many of the published figures of Mougeotias do not show
cytoplasmic residues in the gametangia after union of the gam-
etes, because they are of little or no significance in the identifica-
tion of species. However, they are present in all species of the
genus now known.
The generic names formerly applied to certain species of
Mougeotia include the following: Sphaerocarpus Hassall 1843;
Mesocarpus Hassall 1845; Pleurocarpus Braun 1855; Staurospermum
Braun 1855; Craterospermum Braun 1855; Plagiospermum
Cleve 1868; Sphaerospermum Cleve 1868; Gonatojiema Wittrock
1878. Czurda 1932 included among the Mougeotias certain species
here classified in the genera: Debarya, Mougeotiopsis, and
Temtiogametum.
Key to the Species of MOUGEOTIA
I. With zygospores (rarely aplanospores also present) 2
I. With aplanospores (zygospores rare or unknown) 69
2. Sporangium between 2 undivided gametangia 3
2. Sporangium dividing i of the gametangia 45
2. Sporangium dividing both gametangia 48
3. Sporangia globose, subglobose, ovoid, ellipsoid or dolioform,
longer axis parallel with the conjugating tube 4
3. Sporangia cylindric-oblong with concave sides and rounded
ends 35
3. Sporangia with longer axes at right angles to the conjugating
tubes 38
4. Spore wall smooth 5
4. Spore wall not smooth 22
5. Diameter vegetative cells usually less than 24^4 6
5. Diameter vegetative cells usually more than 24 /a 17
6. Vegetative cells usually less than 12/i in diameter 7
6. Vegetative cells usually between 12^ and 24A1 in diameter 11
7. Spores globose 8
7, Spores ellipsoid or ovoid, longer axis same as that of tube 10