CHYTRIDIALES 171 



Rozella laevis Karling 

 Mycologia, 34: 201. 1942 



"Sporangia solitary, partly or completely filling hypertrophied por- 

 tions of the host hyphae, variable in size and shape, spherical, 20-52 u., 

 clavate, 10-20 u, x 30-1 12 u., broadly and elongately pyriform with 

 1 to 3 exit papillae, 3-4 u. in diam. by 2-3 \x in height. Zoospores hyaline, 

 with a globular spot which is not markedly refractive, obclavate to 

 pyriform, 1.5-1.8 u. x 2.9-3.3 [x; occasionally bi- and multirlagellate, 

 flagellum 10-12 u, long. Resting spores spherical, 11-18 \x, oval, elon- 

 gate or obpyriform with a large central vacuole and coarsely granular 

 cytoplasm; wall smooth and hyaline, 1.5-2 (jl thick; germination un- 

 known" (Karling, loc. cit.). 



Parasitic in Pythium gracile, causing marked hypertrophy, Karling 

 (loc. cit.), United States; Pythium sp., Karling (1944f: 638, figs. 1-19), 

 Brazil. 



For further information on this species, see Karling's account and 

 figures (1944f). As its author indicates, Rozella laevis differs from Ro- 

 zella cuculus primarily in having hyaline rather than brown to pale- 

 yellow resting spores. Just how significant this feature is awaits further 

 study. It will be maintained as a distinct species here. 



Rozella irregularis (Butler) Sparrow 



Mycologia, 30: 377. 1938 



Pleolpidium irregulare Butler, Mem. Dept. Agr. India, Bot. Ser., 1: 123, 

 pi. 8, figs. 1-12. 1907. 



"Sporangia formed in the hyphae of the host, irregular in shape, 

 terminal and intercalary, averaging 23 \x in diameter, with a single 

 papilla; zoospores obclavate, with a single cilium borne posteriorly; 

 durable spores single, free in the cavity of the host-filament which is 

 enlarged to contain them, numerous, 11-15 [J. in diameter, spherical, 

 of a pale yellow colour, with a moderately thick wall, provided with 

 short regular spines; germination not observed" (Butler, loc. cit.). 



Parasitic in Pythium (?) vexans, Butler (loc. cit.), Great Britain; 

 Pythium sp., Gaertner (1954b: 21), Egypt, Northwest Africa, Equa- 

 torial East Africa, South Africa; Gaertner (op. cit., p. 40), Sweden. 



