574 AQUATIC PHYCOMYCETES 



Saprophytic in Characeae and grasses. 



Nephrochytrium superficially resembles Diplophlyctis. It differs from 

 this genus in that "the sporangia and resting spores [of Diplophlyctis] 

 are formed as enlargements of the germ tube [whereas] in the present 

 species [TV. appendiculatum] they develop as protuberances or outgrowths 

 from a transverse, fusiform, spindle-shaped, medianly constricted apoph- 

 ysis. Furthermore, occasional intercalary, spindle-shaped swellings oc- 

 cur in the rhizoidal system, while the zoospore case becomes thick- 

 ened, amber in color, and persists on the surface of the host cell as an 

 appendage to the sporangia and resting spores" (Karling, loc. cit.). 



Unfortunately, the critical point as to whether the sporangium is 

 operculate or inoperculate has not been determined in Nephrochytrium 

 appendiculatum, the type species. Couch (1938a) has identified with 

 Karling's genus an operculate form with a similar type of development. 

 Because of the frequent parallelisms in body structure known to exist 

 in these fungi, it is impossible to say without a reexamination of Kar- 

 ling's fungus whether Couch's N. stellatum and Whiffen's N. aurantium 

 should be placed here or in a genus of their own. 



KEY TO THE SPECIES OF NEPHROCHYTRIUM 



Globule of zoospore colorless 



Apophysis elongate, transverse, spindle-like; resting spore smooth- 

 walled N. appendiculatum, p. 574 



Apophysis globose, ovoid, or lobed; resting spore with a stellate wall 



N. stellatum, p. 575 

 Globule of zoospore orange N. aurantium, p. 576 



Nephrochytrium appendiculatum Karling 



Amer. J. Bot.. 25: 211, figs. 1-2. 1938 



(Fig. 34 F-G, p. 571) 



"Zoosporangia numerous, hyaline, smooth, sub-spherical, flattened, 

 depressed, usually somewhat kidney-shaped, 8 X 14 \x — 18 x 30 [i, 

 with 1-3 exit papillae or tubes of varying length. Zoospores hyaline, 

 spherical, 3.5-4.5 \x, with a large clear refractive globule; cilium approx- 

 imately 40 [x long; zoospore case becoming thick-walled, amber colored, 



