392 AQUATIC PHYCOMYCETES 



shape. Sometimes with approaching maturity, additional vesiculations 

 may occur on the dorsal side of the rhizoids. A few of them contain 

 nuclei obtained apparently from the incipient sporangia. If the nuclei 

 remain and multiply, septa form. Secondary sporangia then develop 

 and the thallus becomes polycentric. Such instances, however, are the 

 exception; only three were observed. Early stages of resting spores 

 cannot be distinguished from sporangia. No sexuality was evident. 

 It should be noted that the remarkable method of formation of the 

 sporangium by vesiculation along the rhizoids, a striking feature well 

 borne out by the figures and description of development, is not referred 

 to in the generic diagnosis. 



Phlyctorhiza endogena Hanson 



Amer. J. Bot., 33: 732, figs. 1-49. 1946 



(Fig. 24 E-G, p. 396) 



"Zoosporangia hyaline, smooth, flattened, depressed, usually some- 

 what kidney-shaped, 6 x 10-33.6 x 58.2 [jl, frequently oval, 7 x 12-26.2 

 X 42 u., irregular, 1 1 x 20-29 x 36[x; with one basal, rarely lateral or 

 apical exit pore, 2.9-4 x 5.2-7.5 \i in diameter. Sporangia developing 

 as an outgrowth of the germ tube while the zoospore usually persists 

 as a cyst. Rhizoidal system oriented on the base and periphery of the 

 sporangium, often vesiculate at point of origin, frequently anastomosing, 

 extending from 15-300 [jl beyond the sporangium; vesiculate portions 

 of rhizoids 3-8 \i in diameter. Zoospores elliptical, 2.2-2.9 x 2.9-3.7 

 (jl, with one centric or excentric refractive globule; flagellum 20-26 [i 

 long, emerging and swarming in a vesicle outside of the sporangium. 

 Resting spores oval, 8.6-12 x 15-20 [x, reniform, 8.2-16.4 x 10.4-21.6 

 [jl, irregular, 12-21.2 x 24-29 [jl, with light golden to deep amber, 

 smooth undulate, or tuberculate walls, 0.746-1.5 ;jl thick; contents 

 densely and coarsely granular; upon germination functioning as 

 prosporangium" (Hanson, loc. cit.). 



Mosquito integuments, remains of mayflies, dragonflies, and gnats, 

 United States. 



Two other species, Phlyctorhiza variabilis Karling (1947a: 27, figs. 

 1-48) and P. peltata Sparrow (1950: 52, figs. 1-7) have been referred 

 to this genus. 



