832 AQUATIC PHYCOMYCETES 



JAPONOCHYTRIUM Kobayasi and Ookubo 



Bull. Nat. Sci. Mus. (Tokyo), 33: 57. 1953 



(Fig. 63 E-F, p. 824) 



Thallus epi- and endobiotic, monocentric, eucarpic; zoosporangium 

 epibiotic, smooth, inoperculate, at maturity forming an apical discharge 

 pore, never bursting; endobiotic part composed of an apophysis and 

 rhizoids, the apophysis connected with the sporangium by a somewhat 

 long neck, spheroid, smaller than the sporangium, rhizoids short, 

 branched; zoospores few within the sporangium, liberated through a 

 pore one by one as flagellate bodies, the two flagella laterally attach- 

 ed and oppositely directed; resting spore not observed. (Modified 

 from Kobayasi and Ookubo.) 



Inhabitants of marine algae. 



The genus differs from Thraustochytrium primarily in the formation 

 of a subsporangial apophysis and in liberation of the zoospores through 

 a discrete pore, not by bursting of the sporangial wall. 



Japonochytrium marinum Kobayasi and Ookubo 

 Bull. Nat. Sci. Mus. (Tokyo), 33: 60, fig. 5. 1953 



Sporangia scattered on the host cell, shortly stipitate or sessile, 

 spheroid or more ovoid, 16-30 u. high by 10-20 u. in diameter, somewhat 

 thick-walled, smooth, hyaline, distinct from the cylindrical, 3-5 \i long 

 by 3-4 u. thick, stalk; apophysis vesicular or ovoid, smaller than the spo- 

 rangium, 10-13 u. long, 5-10 \i in diameter, thin-walled, hyaline, rhizoids 

 usually arising from one or two axes produced at the base of the apoph- 

 ysis, generally stout, up to 3 ;jl in diameter at the point of origin, 

 branched; zoospores ten or more formed in one sporangium, at first 

 spheroid, then reniform, 4-5 u. in diameter, with two laterally attached 

 flagella, containing one to several refractive globules, slowly swimming 

 away through the apical pore of sporangium, varying in form when 

 swimming; resting spore not observed. (Modified from Kobayasi and 

 Ookubo.) 



On Gracilaria confervoic/es, Cladophora juponica (in culture dish), 

 Japan. 



