CHYTRIDIALES 323 



thicker walled zoospore cyst, with a thick, smooth, hyaline, 2.5-3 u. 

 wall, 13-21 [i in diameter, contents finely granular, 8-15 jj. in diameter, 

 with a large eccentric globule, apparently asexually formed, germina- 

 tion not observed" (Sparrow and Barr, 1955: 550). 



Parasitic in IGloeodinium sp. (det. G. M. Smith), United States. 



PHLYCTOCHYTRIUM Schroeter 

 Engler and Prantl, Naturlichen Pflanzenfam.. 1 (1): 78. 1892 (1893) 



(Fig. 19 H-I, p. 318) 



Phlyctidium (Braun) Rabenhorst, Flora Europaea algarum, 3:278. 



1868; Schroeter, pro parte, Kryptogamenfl. Schlesien, 3 (1): 190. 1885. 

 Rhizidium sensu Fischer, Rabenhorst. Kryptogamen-H., 1 (4): 106. 1892. 



Non Braun, Monatsber. Berlin Akad., 1856: 591. 



Thallus epi- and endobiotic, monocentric, eucarpic, consisting of 

 the epibiotic rudiment of the sporangium, the endobiotic apophysis, 

 and the branched rhizoidal system; sporangium inoperculate, epi- 

 biotic, uni- or multiporous, separated by a cross wall from the endo- 

 biotic system, zoospores posteriorly uniflagellate, generally with a 

 single globule, formed within the sporangium; resting spore borne 

 like the sporangium, thick-walled, apparently asexually produced, 

 upon germination forming a zoosporangium or prosporangium. 



Primarily parasites and saprophytes in fresh-water algae. Less often 

 found on fungi and in rotting parts of higher plants. 



The method of infection, establishment of the rhizoids, and for- 

 mation of the apophysis are essentially like that in Entophlyctis except 

 that the epibiotic part persists, receives the contents of the endobiotic 

 system, and becomes the sporangium. Apophysate species of Chytrid- 

 ium, as C. lagenaria for example, exhibit the same sequence of devel- 

 opment as does Phlyctochytrium, but have never been segregated from 

 Chytridium as have the inoperculate forms from Rhizophydium. This 

 separation of apophysate from nonapophysate species has in most 

 instances been readily accomplished. In several, however, the sub- 

 sporangial swelling is not always definite, and in at least one (P. bi- 

 porosum) it appears to be inconstant in its occurrence. 



