CHYTRIDIALES 143 



spore endobiotic, globose, with a thick colorless smooth wall, 16 fx in 

 diameter, contents colorless, with a large oil globule. 



In uredospores of Puccinia airae, P. violae, and P. rhamni, but not 

 capable of infecting uredospores of certain other rusts, Germany. 



Olpidium allomycetos Karling 

 Amer. J. Bot., 35: 508, figs. 1-32. 1948 



"Sporangia single to numerous in host cell, hyaline, smooth, spheri- 

 cal (8-38 [A oval (10 > 16-20 x 30 (jl), pyriform (8 < 15-24 x 33 fx), 

 or occasionally angular with one short or long exit tube, 5 to 10 ^ 

 broad by 9 to 220 a long. Zoospores, oval (4 x 5.5 y.) elongate (3.6 x 

 6.4 [x) slightly curved, with 4-9 refractive globules; flagelium 14-16 [x 

 long. Resting spores partly or completely filling a hyaline vesicle, 

 smooth, hyaline, spherical (6-30 [Jt.), oval (1 x 14-18 x 27 (jl) or slightly 

 angular, containing numerous refractive granules or globules; forming 

 zoospores directly upon germination" (Karling, loc. cit.). 



Parasitic in AUomyces anomalus, and by inoculation in A. arbuscula, 

 A. javanicus, A. cystogenes, A. moniliformis, Rhizophlyctis (Karlingia) 

 rosea, and in rotifer eggs, Karling (loc. cit.), United States; A. ar- 

 buscula, Sparrow (1952a: 35), Cuba. 



Karling was able to infect thalli of Rhizophlyctis (Karlingia) and roti- 

 fer eggs by using zoospores of the AUomyces parasite, a most remark- 

 able range of hosts. 



The species is of particular interest since it appears to be only the 

 second aquatic species in which germination of the resting spore has 

 been observed. In undergoing germination a localized area of the rest- 

 ing spore becomes resorbed and ruptures. A broad discharge tube, 

 sometimes almost equal to the diameter of the spore gradually devel- 

 ops. This structure penetrates the wall of the host cell and extends 

 as a somewhat contorted tube of irregular diameter and up to 120 [i. 

 in length. If growth is inhibited by the host wall, a globular vesicular 

 sporangium-like structure is formed. Zoospores of the same size, shape, 

 and behavior as those produced by the sporangia are discharged and 

 these directly infect resting spores of AUomyces. There were no evidences 

 of sexuality. 



