160 AQUATIC PHYCOMYCETES 



straight or somewhat crooked tapering radiating discharge tubes, all 

 of which usually penetrate the host wall; zoospores 2.2—3 (x in diam- 

 eter (up to 3.6 [x long when elongated), ovoid, the broader end 

 anterior, with a small colorless refractive globule and several coarse 

 granules, flagellum attached to the narrower end, escaping through 

 the discharge tubes upon the dissolution of their apices and forming 

 temporary groups, capable of amoeboid movement; resting spore not 

 observed. 



Parasitic in mycelium, gemmae, and suspensors of Pilobolus crystal- 

 linus var. areolata, P. kleinii, Germany. 



In Zopfs second account of the species (1892:7) the vegetative 

 stage was described. His observations indicated that the fatty material 

 of the host which was colored with carotene was absorbed by the amoe- 

 boid th alius. The contents of the maturing sporangium also appear 

 from the figures to be orange red, but are evidently colorless at matur- 

 ity, since the zoospores possess no pigmentation. 



The chytrid was parasitized by a monad, Endobiella destruens Zopf. 



Considerable variation in the size of the sporangia and the number 

 of discharge tubes was noted. The largest sporangia usually occurred 

 singly, formed about a thousand zoospores and had up to thirty dis- 

 charge tubes; smaller ones contained fewer spores and discharge tubes, 

 the smallest bearing only one or two tubes. 



Pleotrachelus zopfianus Morini 

 Mem. R. Accad. Sci. Istituto Bologna, Ser. VI, 10: 301, figs. 1-4. 1913 

 Sporangium spherical or subspherical, pale yellowish orange, 41- 



47 a in diameter, with from one to two cylindrical discharge tubes; 



zoospores ovoid-pyril'orm. uniflagellate, 3-4 y. long; resting spore 



spherical, thick-walled, upon germination cracking open and liberating 



zoospores. 



In the bicellular trophocysts of Pilobolus pirottianus, Italy. 

 Doubtfully distinct from Pleotrachelus fulgens. 



Pi iuirachelus wildemani H. E. Petersen 



Annales Mycologici, 8: 553, fig. XXVc. 1910. Emend. Ingold, Trans. Brit. 



Bryol. Soc, 2: 53, fig. 1. 1952 



