248 AQUATIC PHYCOMYCETES 



R.HIZOPHYDIUM CHYTRIOPHAGUM Ajello 



Mycologia, 37: 113, figs. 14-28. 1945 



"Zoosporangia epibiotic, eucarpic, spherical, 10-30 \x in diameter, 

 hyaline, smooth-walled, attached to the host by a tubular haustorium 

 4.2-7.3 [x long, 2.2 u. wide, with short lateral extensions 1.5 p. long. 

 Zoospores spherical, 2.2-2.9 fj. in diameter with a single posterior 

 flagellum 15 \i long, and a centrally located refractive globule. Resting 

 spores extramatrical, spherical, 6-15 (j. in diameter, wall 1.4 u, thick, 

 golden-brown in color, at germination functioning as a prosporangium" 

 (Ajello, loc. cit.). 



Parasitic upon Phlyctochytrium aureliae, United States. 



The zoospores are liberated after the sporangium wall ruptures; 

 no discrete pore is evidently formed. 



Ajello noted that the parasite had little or no adverse effect upon 

 the host unless more than one was present or unless infection occurred 

 early in the host's development. 



Rhizophydium chytriomycetis Karling 

 Mycologia, 38: 105, figs. 1-8. 1946 



"Thalli usually numerous, up to 20 on one host sporangium. Spo- 

 rangia hyaline, smooth, sessile or stalked, spherical, 8-30 \x, with one 

 to three exit papillae. Rhizoidal system finely branched, main axis 

 up to 3 u, in diameter. Zoospores hyaline, spherical, 2-2.8 \x, with a 

 minute, .5-. 8 \x, hyaline refractive globule. Resting spores dark brown, 

 spherical, 7-18 \l, with one or more large refractive globules; function- 

 ing as a pro-sporangium in germination" (Karling, loc. cit.). 



Parasitic on Chytriomyces hyalinus and C. aureus, United States. 



This and the following species {Rhizophydium hyper par asiticum) are 

 scarcely separable from one another save on the basis of differences 

 in host plants, which, incidently, are all chytrids. 



Rhizophydium hyperparasiticum Karling 

 Amer. J. Bot., 33: 329, figs. 1-4, 9-13. 1946 

 (Fig. 18, A-E, p. 286) 

 "Thalli, numerous, up to 80 on a host sporangium. Sporangia ses- 



