CHYTRIDIALES 335 



definitely elevated, the zoospores slightly larger (3 \£), and the un- 

 branched (rarely branched) rhizoid never expanded to form a sub- 

 sporangial apophysis. In these respects it approaches Rhizophydium 

 haynaldii and the incompletely known R. rostellatum (de Wild.) 

 Fischer. 



Further study will be necessary to determine the degree of vari- 

 ability of the rhizoidal system in this fungus before it can be said 

 with certainty that all these biporous forms belong to a single species. 



Phlyctochytrium lippsii Lohman 

 Mycologia, 34: 105, figs. 1-15. 1942 



"Zoosporangia external to nutritive host cell, single or aggregated, 

 occasionally short-stalked but typically sessile, obovate when densely 

 clustered, to globose or globose-flattened when free, 7 to 36 [x in diam- 

 eter, with smooth, hyaline to pale yellowish wall which at maturity 

 in the larger individuals is approximately 1 \x in thickness, appearing 

 double, with 1 to 3, occasionally as many as 10, smooth, obtusely 

 rounded exit papillae; zoospores as few as 6 or 8 in small sporangia, 

 as many as 60 or more in the largest; at first narrow elliptic, 3.5^ 

 long but after swimming a few minutes elliptic-ovoid, 3 to 4 \l in diam- 

 eter, with one or two oil drops and posterior flagellum about 25 \x 

 long — at 1 5 to 20° C. swimming before emission, then escaping freely 

 without vesicle formation and swimming away in a zigzag course; 

 subsporangial vesicle thin-walled, variable in size and shape, 2 to 4 \x 

 in diameter and bead-like, or occasionally 8 to 10[x in diameter and 

 broadly fusoid — sometimes not evident; rhizoids dendroid and deli- 

 cate but sometimes from the bead-like apophysis stoutish bifurcate, 

 with delicate terminal branching; resting spores not observed; sporan- 

 gia viable after normal desiccation for 6 weeks at room temperature" 

 (Lohman, loc. cit.). 



Parasitic on Ascobolus immersus, A. leveillef, A. stercorarius, As- 

 cophanus holmskjoldii, Lasiobolus equinus, and Sordaria coronifera; 

 typically upon free or undischarged ascospores of Ascobolus, United 

 States. 



