LEPTO MIT ALES 873 



LEPTOMITUS Agardh 

 Systema algarum, p. 47. 1824 

 (Fig. 69 A-B, p. 875) 

 Apodya Cornu, Ann. Sci. Nat. Bot., V, 15: 14. 1872. 



Thallus stout at the base, filamentous throughout, monopodial, 

 dichotomously branched near the base, the hyphae constricted and 

 pseudoseptate at intervals, the branches arising at the constrictions, 

 apparently without specialized holdfasts, each segment containing one 

 or more cellulin discs; sporangia formed from unspecialized or lateral 

 segments of the mycelium, terminal or developed in basipetal succession ; 

 zoospores formed in the sporangia in one row (occasionally irregularly 

 disposed), diplanetic, the primary spores apically biflagellate, emerging 

 through a terminal or lateral pore, encysting after a period of swarming, 

 secondary spores laterally (?) biflagellate; sexual organs not observed. 



Saprophytic on debris, often in heavily polluted fresh waters. 



The secondary zoospore is described only as being biflagellate. 



Leptomitus lacteus (Roth) Agardh 

 Systema algarum, p. 47. 1824 



Conferva lactea Roth, Catalecta botanica, 2: 216. 1800. 



Leptomitus libertiae Agardh, he. cit., p. 49. 1824. 



Saprolegnia lactea Pringsheim, Jahrb. wiss. Bot., 2: 228, pi. 23, figs. 6-10, 



pi. 25, figs. 1-6. 1860. 

 Apodya lactea Cornu, Ann. Sci. Nat. Bot., V, 15: 14. 1872. 

 Saprolegnia corcagiensis Hartog, Quart. J. Micro. Sci. (N. S.), 27: 429. 



1886-87. 



Basal segment stout, up to 48 u. in diameter, branches 8-16 \x in 

 diameter, the segments up to 400 \x in length; zoosporangia cylindrical, 

 formed from slightly swollen segments of the mycelium, primary zoo- 

 spores pyriform, 10.5-1 1 jjl in diameter, secondary zoospores biflagellate. 



Forming large turflike masses often of great extent on organic debris, 

 particularly in waters with a high organic content, rarely in purer waters. 

 Roth {he. cit.), Agardh (be. cit.), Braun (1851:287), Pringsheim 

 (1860: 228, pi. 23, figs. 6-10, pi. 25, figs. 1-6; 1883a: 288, pi. 7, figs. 1-9), 

 Biisgen (1882: 266, pi. 12, figs. 9-15), Schroeter (1885: 255), Kolkwitz 



