954 AQUATIC PHYCOMYCETES 



Olpidiopsis verrucosa Johnson 

 J. Elisha Mitchell Sci. Soc, 71 : 60, figs. 1-24. 1955 



"Zoosporangia terminal in the host hyphae, infrequently in short 

 lateral branches; oval or spherical, very rarely pyramidal; 28 X 40 \x 

 -84 x 103 [i, spherical ones 42-92 \i in diameter; smooth; commonly 

 with one or two exit tubes. Zoospores laterally biflagellate, isocont; 

 oval or ellipsoid, rarely irregular; 3.6-4.8 \i in length by 2.4-3.0 [x in 

 diameter. Resting spores (oogonia) oval, occasionally spherical, never 

 ellipsoid; 22 x 26 U.-63 x 67 \x, predominantly 42-50 49-56 \i, 

 inclusive of exospore. Exospore verrucose, crenulate, squarrose, or 

 rugulose, infrequently irregular or bullate, rarely smooth, never echin- 

 ulate; 1.4-8.4 \i thick. Companion cells (antheridia) 1-5 on a resting 

 spore; spherical, occasionally ellipsoid or oval; smooth; 11-28 \x, 

 predominantly 14-22 [i in diameter. Resting spore germinating by a 

 single germ tube penetrating through the companion cell, the contents 

 forming laterally biflagellate, isocont planonts" (Johnson, loc. cit.). 



Parasitic in Achlya glomerata, from soil, United States. 



The species differs from Olpidiopsis vexans and O. incrassata prima- 

 rily in configuration of the exospore of the resting spore and in the host 

 range. 



IMPERFECTLY KNOWN SPECIES OF OLPIDIOPSIS 



? Olpidiopsis elliptica (Schroeter) Fischer 

 Rabenhorst. Kryptogamen-Fl., 1(4): 41. 1892 



Diplophysa elliptica Schroeter, in Cohn, Kryptogamenfl. Schlesien, 3 (1): 

 196. 1885. 



Resting spore transversely ellipsoidal, occupying nearly the whole 

 breadth of the host cell, with light-brown wall covered with delicate 

 spines; companion cell slightly smaller than the resting spore, with a 

 smooth brown wall; sporangium and zoospores not observed. 



In Mougeotia sp., Germany. 



? Olpidiopsis vuilleminiae Arnaud 



Bull. Soc. Mycol. France, 68: 182, fig. 1C. 1952 

 An incompletely described form having ovoid sporangia (?), 

 sometimes with protuberances, occurring in the sterile hypertrophied 

 basidia of Corticium comedens, France. 



