340 AQUATIC PHYCOMYCETES 



ical, 12-35 u. in diameter, colorless, covered with numerous hyaline, 

 solid, bicornuate teeth, 3.5-4.5 jj. long and 3.5-6.5 \l wide, single pronged 

 teeth occasionally formed, tips of teeth at times becoming filiform 

 and elongate, attaining lengths of 20 to 50 \x\ endobiotic system approx- 

 imately 1 50 [j. long consisting of a spherical apophysis, 3-7 u, in diam- 

 eter, sometimes irregular or elongate with well developed rhizoids that 

 branch profusely. Zoospores spherical, 4-4.5 jx in diameter, with a 

 single centrally situated refractive globule, 2 \x in diameter and a single 

 posterior flagellum, 1 5—20 jx long. Resting spores unknown" (Ajello, 

 loc. cit.). 



Saprophytic on decaying vegetation, Ajello (loc. cit.), shrimp skele- 

 ton, Sparrow and Barr (1955: 554), United States; insect exuviae, 

 Ajello (loc. cit.), Sparrow (1937a: 28, fig. 1 k, pi. 1, fig. 19), Denmark. 



The Danish material is probably referable to this species; possibly, 

 to the next one, Phlyctochytrium mucronatum. 



Phlyctochytrium mucronatum Canter 

 Trans. Brit. Mycol. Soc, 32: 240, figs. 1, 2. 1949 



"Thallus epibiotic, monocentric, consisting of a sporangium, apoph- 

 ysis and extensive rhizoidal system. Sporangia more or less spherical 

 5.7-31 [x in diameter (including spines), with a single pyramidal apical 

 spine 1.4-5.2 u. long x 0.9-4.3 jj. broad at the base and with one to 

 four whorls of lateral simple, or T-shaped spines (absent in very small 

 sporangia). Sporangium dehiscing by a lateral pore; contents emerging 

 in an undifferentiated mass continuous with the sporangium. Zoospores 

 spherical, 4-5 \i in diameter, with a posterior oil globule, above which 

 is a clearer area with a black granule; remainder of the protoplasm 

 is coarsely granular. Apophysis spherical 1.3-3.5 u. in diameter. Rhi- 

 zoidal system one to three main axes leaving the apophysis, often 

 branching dichotomously and tapering towards their extremities, up 

 to 85 \x long. Resting spores not observed" (Canter, loc. cit.). 



Saprophytic on Closterium pritchardianum, C. costatum, Great 

 Britain. 



In contrast to Phlyctochytrium aureliae, the spines occur in one 

 to four whorls, not haphazardly, on the sporangium. 



The sporangia were attacked by a chytridiaceous hyperparasite. 



