924 AQUATIC PHYCOMYCETES 



Sporangia monosporangiate ; parasitic in Pythiaceae 



Parasitic in Pythium and Zoophagus R. inflata, p. 925 



Parasitic in Phytophthora R. waterhouseii, p. 926 



Rozellopsis septigena Karling 



Mycologia, 34: 206. 1942 



(Fig. 75 G, p. 939) 



Sporangia in linear series, somewhat inflated or cylindrical, with one 

 or two exit papillae; zoospores narrowly ovoid or pyriform, laterally 

 biflagellate, the posterior flagellum twice the length of the anterior one, 

 5-8 [i long by 3-4 [i broad; resting spores in swollen lateral branches of 

 host, spherical, 20 [X in diameter, wall brown, covered by tenuous 

 spines 2 (jl long, contents with a large oil globule, germination not 

 observed. 



Parasitic in hyphae of Saprolegnia sp., not capable of infecting 

 Achlya, Fischer (1882), Minden (1915: 272), Germany; Saprolegnia sp., 

 Prowse (1951:400, fig. 1-2; pi. 18), Great Britain; Saprolegnia sp., 

 Sparrow (1952d: 759), United States. 



The septate Plasmodium is known to arise from a single zoospore 

 infection. 



Karling (1942a: 34; 1942b: 206) treats the fungus Fischer misiden- 

 tified with Cornu's Rozella septigena as though it were a new species 

 described by Fischer. In the interests of clarity a new species name could 

 well have been applied to Fischer's fungus, but since Cornu's name was 

 carried over to a new genus it is valid. Rozella septigena Fischer, 

 however, does not exist, hence, cannot be a synonym. 



Prowse (1951) investigated the method of infection, development of 

 the sporangia and liberation of the spores in Rozellopsis septigena. 

 He offers no evidence as to whether or not the basipetalously developed 

 sporangia arise from a single infection but indicates that the cross walls 

 appear to be laid down by the host and not by the parasite. The zoo- 

 spores are described as pyriform, hyaline, with two or sometimes four 

 refractive granules, 3 by 5-6 \x, with a long (10 u.) posterior flagellum 

 and a short (5 \x) anterior one. It is also clear that the species is restricted 

 in its parasitism to certain members of Saprolegnia and will not attack 



