CHYTRIDIALES 541 



flagellum 9-12 [x long; swarming actively in a vesicle outside of the 

 sporangium. Single rhizoidal axis attached at base of sporangium, 

 sparsely branched and sometimes extending for a distance of 120 \j.. 

 Resting spores hyaline, smooth, [spherical], 7-12 (x, or oval with a large 

 central globule surrounded by several smaller ones; content emerging 

 through a pore in the wall during germination and forming a superficial 

 sporangium" (Karling, he. cit.). 



Weakly parasitic on Closterium rostratum, United States. 



Apparently confined to one host species. It does not attack other 

 species of Closterium or members of other genera of green algae. 



Chytriomyces hyalinus Karling 



Amer. J. Bot., 32: 363, figs. 46-61. 1945 



Chytriomyces nodulatus Haskins, Trans. British Mycol. Soc, 29: 137, rigs. 

 1-8. 1946. 



"Sporangia hyaline, smooth, usually spherical, 10-60 \i; operculum 

 apical or subapical, shallow, saucer-shaped, 8-16 u in diam. Zoospores 

 oval, 3-3.5 X 5-5.5 (x, with a small (1-1.5 [x), hyaline refractive globule; 

 flagellum 18-20 ;x long; zoospores emerging and swarming in vesicle, 

 1-16 minutes before breaking out and swimming away; vesicle contin- 

 uous with interior of sporangium. Apophysis when present spherical, 

 subspherical, fusiform, or elongate, 3-7 [X in diam. Rhizoidal system 

 well developed, main axis up to 7 [i in diam.; extending for a distance 

 of 300 pi. Resting spores spherical (10-20 jx), oval (6-8 x 10-14 (x), 

 elongate, clavate, pyriform, or slightly irregular, with a smooth, thick 

 (2[x), light-brown wall; containing a large central refractive globule 

 surrounded by a few to several smaller ones; functioning as prospo- 

 rangia in germination" (Karling, he. cit.). 



Saprophytic in exuviae and on chitin, Brazil; Karling (be. cit.; 

 1948c: 509), chitin, Sparrow (Michigan), United States; from soil, 

 substrate ?, Gaertner (1954b: 22), Northwest Africa, South Africa. 



Common in bogs in Michigan; nodulate as well as smooth-walled 

 sporangia were observed. 



The species frequently occurs in company with Polychytrium aggre- 

 gation on purified shrimp chitin bait. 



