LAGENIDIALES 933 



records of Olpidiopsis saprolegniae on Ach/ya are open to question. In 

 fact, Karling (1942e) has gone so far as to suggest that if these cross- 

 inoculation studies are confirmed, it might be expedient, because of the 

 lack of constancy in morphological characters, to lump all the Olpidiop- 

 sis parasites of Saprolegnia, with the possible exception of O. irregularis, 

 under O. saprolegniae. 



Olpidiopsis saprolegniae var. levis Coker 

 The Saprolegniaceae, p. 185, pi. 62, figs. 1-6. 1923 



"Sporangia spherical to elliptic, smooth, very variable in size and 

 number, usually occupying the swollen ends of hyphae but not rarely 

 also in intercalary swellings; emptying by one or two tubes which 

 penetrate the host's wall but go little beyond and are usually short, at 

 times however as long or longer than the diameter of the sporangium; 

 spores very minute and numerous, probably with two cilia, swimming 

 rapidly, emerging at first through internal pressure and probably show- 

 ing the same sequence as described in preceding species but not all 

 stages observed. Oogonia elliptic to nearly spherical, with the wall 

 rather thick and quite smooth and even; antheridial cells smaller than 

 the oogonia, smooth, thin-walled, one or two attached to each oogo- 

 nium, their contents usually disappearing entirely by the time the oogonia 

 are mature" (Coker, he. cit.). 



Parasitic in Saprolegnia ferax, S. monoica, United States. 



Olpidiopsis braziliensis, nom. nov. 



Pseudolpidiopsis achlyae Viegas and Teixeira, Bragantia, 3: 225, pi. 2. 1943. 



Sporangium spherical or elliptical, rarely cylindrical, 20-70 by 16-60u., 

 with a thin, smooth wall, with one or two cylindrical or conical exit 

 tubes 8-28 by 6 [jl; zoospores 4-8 \x in diameter, immediately after 

 discharge spherical and remaining quiescent at orifice of discharge tube, 

 monoplanetic, biflagellate, reniform when actively swimming; resting 

 spore spherical, hyaline, 40-44 \x in diameter, with granular contents 

 and central globule, wall smooth, 2 \x thick; companion cell single, 

 globose or ellipsoidal, 20-30 \x in diameter, hyaline, smooth-walled, 

 germination not observed. 



