BLASTOCLADIALES 657 



The parasite attacked and destroyed both sporophyte and gameto- 

 phyte stages of Allomyces arbuscula and A. javanicus. On the latter host 

 it was particularly voracious and completely destroyed the sporophyte 

 even before resting spores of the host could be formed. As Couch 

 remarks, it is doubtful if the parasite could survive in nature on this 

 plant, presumably "eating itself out of house and home." Although 

 Blastocladiella simplex was successfully inoculated, none of the other 

 three species of that genus or species of Achlya or Saprolegnia was 

 attacked. 



Catenaria sphaerocarpa Karling 

 Amer. J. Bot., 25: 328, figs. 1-34. 1938 



"Thallus predominantly polycentric, occasionally monocentric. Zoo- 

 sporangia hyaline, smooth, usually spherical, 8-50 [i, oval, 8 > 1 jjl — 30 

 X 33 (jl, and sometimes spindle-shaped, 7 > 14 jji — 15 25 jjl, with 1-3 

 straight, curved, or irregular exit tubes, 5-600 \i long and 2.5-4 [j. in 

 diameter, which may end flush with the surface of the host cell or 

 extend 3-200 u, beyond it. Zoospores spherical, 4-4.8 fi. with a single, 

 large hyaline refractive globule; cilium approximately 25 [i long; 

 emerging singly in succession and after a momentary pause swimming 

 away. Isthmuses between sporangia of variable length, rarely inflated 

 and spindle-shaped. Rhizoids numerous, well developed and branched, 

 arising from the isthmuses as well as from the sides and ends of the 

 sporangia. Resting spores usually spherical and oval, 10-25 [i, occa- 

 sionally spindle-shaped and elongated with a heavy brown wall 1.5-2.5 

 (j. thick, and an evenly granular content; apparently developed in the 

 same manner as the zoosporangia; germination unknown" (Karling, 

 he. cit.). 



Saprophytic in cells of Hydrodictyon reticulatum, Char a coronata, 

 Nitella flexilis, Cladophora glomerata, Pithophora sp., Spirogyra crassa, 

 Elodea canadensis, and root tips of Zea mays and Allium cepa, Karling 

 {be. cit.), dead Cladophora, Sparrow ( 1943 : 320), United States; snake- 

 skin bait, from soil, Sparrow (1952b: 71), Cuba. 



Couch (1945a) has rejected this as a species of Catenaria because of 

 the chytridiaceous nature of the zoospore. It possibly belongs in Sep- 

 tochytrium but is retained here provisionally. 



