438 AQUATIC PHYCOMYCETES 



KEY TO THE SPECIES OF RHIZOPHLYCTIS x 



Sporangium pyriform or bursiform, small (12-15 by 7-10 \x), zoospores 



few (from four to six) R. borneensis, p. 438 



Sporangium spherical, ovoid, ellipsoidal, clavate, or irregular, gener- 

 ally larger, zoospores numerous 

 On blue-green algae 



Sporangium spherical or ellipsoidal, with a discharge tube, rhi- 



zoids delicate throughout; on Calothrix . . R. mastigotrichis, p. 439 

 Sporangium subspherical or slightly angular, with a short broad 

 apical papilla, rhizoids sometimes expanded distally; on 



Tolypothrix R. tolypotrichis, p. 439 



In moist soil, vegetable debris, or on chitinous substrata 



Sporangium typically forming a variable number of discharge 

 pores or tubes 

 Sporangium contents rose red, becoming brownish red at ma- 

 turity ; zoospores with one or more globules ; resting spore 

 smooth-walled, irregular in shape; on damp soil, vege- 

 table debris R. rosea, p. 441 



Sporangium contents golden red, or colorless 

 Sporangium contents golden red; resting spore spiny to ver- 



rucose R. spinosa, p. 443 



Sporangium contents colorless 



Zoospores with numerous minute globules, resting spore 

 wall often with faint striations; chitinophilous 



R. chitinophila, p. 444 

 Zoospores with a single large globule; on vegetable debris 



R. hyalina, p. 445 

 Sporangium typically forming a single broad discharge tube; 



contents with orange-brown droplets R. petersenii, p. 445 



Rhizophlyctis borneensis Sparrow 



Trans. Brit. Mycol. Soc, 21 : 150, fig. 2 f-h. 1938 



Sporangium free, pyriform or bursiform, 12-15 \i long by 7-10 a in 

 diameter, smooth-walled, with a broad papilla; rhizoids from one to 

 three, arising from the middle or lower part of the sporangium, generally 

 branching in the vicinity of the host cell, polyphagous; zoospores 

 spherical, uniflagellate, from four to six formed in a sporangium, 4 u. 

 in diameter; resting spore not observed. 



1 See also R. ingoldii Sparrow (1957a) and recently described taxon, p. 446. 



