456 AQUATIC PHYCOMYCETES 



Polyphagus ramosus Jaag and Nipkow * 

 Berichte Schweiz. Bot. Gesell., 61: 493, pis. 14, 15. 1951 



Prosporangium sessile on the gelatinous envelope of the host colony, 

 ellipsoid, fusiform, or irregular, with a thin, smooth, hyaline wall, with 

 one or more main rhizoidal axes which give rise to numerous branches 

 the tips of which enter the host cells; sporangium an elongate, saccate, 

 clavate, lateral outgrowth, 30-60 \x long by 14-18 jj. in diameter, usually 

 with the apex protruding beyond the colonial sheath; zoospores fifty 

 to one hundred in a sporangium, spherical, 4-5 \x in diameter, with a 

 large eccentric globule and posterior flagellum 40 \x long, escaping upon 

 the gelatinization of the sporangium apex in a slimy mass and swimming 

 away after a few minutes ; resting spore formed in the tip of the con- 

 jugation tube, subglobose or ellipsoidal, 12-24 \i long by 10-16 (j. in 

 diameter, wall thick, dark-colored, beset with numerous spines, germi- 

 nating after a few days to form a sporangium (as a lateral outgrowth) 

 which produces about twenty zoospores differing in no respect from 

 those in typical sporangia. 



Parasitic on the plankton alga Sphaerocystis schroeteri, Switzerland. 



Similar to Polyphagus parasiticus on Tribonema but differing from it 

 in having smaller zoospores and in being parasitic on Sphaerocystis. 



The fungus is apparently host specific, since colonies of Pandorina 

 and Eudorina occurring with it in the plankton were not infected. 



SPOROPHLYCTIS Serbinow 



Scripta Bot. Horti. Univ. Imper. Petro., 24: 163. 1907 



(Figs. 4 X-Y, p. 72: 29 C-E, p. 450) 



Thallus monocentric, eucarpic, consisting of a reproductive rudiment 

 (the body of the encysted spore) and a tapering main rhizoidal axis from 

 which arise numerous secondary branches, tips of the ultimate branches 

 endobiotic; prosporangium developed from the body of the encysted 

 spore; aplanospores or zoospores formed in an inoperculate thin-walled 

 sporangium produced laterally on the prosporangium, liberated upon 

 rupturing of the sporangium wall; resting spore thick-walled, formed 

 by the receptive thallus after conjugation of two unlike-sized thalli, the 



1 See Paterson (Mycologia, 50:94. 1958). 



