512 AQUATIC PHYCOMYCETES 



Chytridium mucronatum Sparrow and Barr 

 Mycologia, 47: 552, figs. 24-27. 1955 



"Zoosporangium ovate or pyriform, sessile or with a very short stalk, 

 17.5-23.8 \x high by 1 1.2-15.4 [l in diameter, the apex terminated by a 

 mucronate, solid operculum, 5-6 jj. high by 5 u in diameter, wall smooth, 

 colorless, thin except at the base where the remnants of the zoospore 

 cyst persist; endobiotic system consisting of a short stalk which broad- 

 ens into a globose apophysis 5-9.8 ;j. in diameter from which emerge 

 numerous, delicate, branched rhizoids which ramify throughout the 

 host cell; zoospores emerging in an amoeboid mass after dehiscence of 

 the operculum and remaining quiescent for a few minutes, then swim- 

 ming away with a hopping movement, globose, 4.5-5.6 y. in diameter, 

 containing an eccentric, colorless, refractive globule 1-1 .5 u, in diameter, 

 and numerous minute granules, flagellum 24-28 jj. in length; resting 

 spore not observed" (Sparrow and Barr, op. cit. :553). 



Parasitic on Oedogonium sp., United States. 



Chytridium cejpii Fott 



Z. Vestnik Krai. ces. Spol. Nauk. Tr. Matem.-Pfivo. Roc., 1950: 9, figs. 1-6, 



plate. (1951) (separate.) 



"Sporangium upright, obovoid, affixed to the substratum with a basal 

 spheric protuberance, the old zoospore. Length of the sporangium 

 35-45 [x, its breadth 15-21 ;x; spheric protuberance 3-4 a in diameter. 

 Membrane firm, refractive, colourless. Operculum large, 10-15 jj. in 

 diameter, rejected after discharge of zoospores. Zoospores subspheric, 

 3-4 jjl in diameter, with a typical eccentric oil drop, uniciliate, leaving 

 successively the sporangium. Subsporangial vesicle (apophysis) small, 

 spheric, 3-5 \x in diameter, connected by a fine thread with the protuber- 

 ance. No rhizoids observed, resting spores unknown" (Fott, he. cit.). 



Collected on Vaucheria sessilis DC, Czechoslovakia. 



At this point, Chytridium scherffelii Berczi (non Sparrow) (1940: 85, 

 pi. 2, figs. 30-37) should be considered. Although resembling both this 

 and C. sexuale, it is closer to C. cejpii. Berczi's binomial is preempted 

 by C. scherffelii Sparrow 1936. To effect a nomenclatorial change, until 

 the status of these three species is clarified by further study, seems 

 undesirable at this time. 



