CHYTRIDIALES 401 



IMPERFECTLY KNOWN SPECIES OF RHIZOSIPHON 



? Rhizosiphon akinetum Canter 

 Trans. Brit. Mycol. Soc, 37: 123, text figs. 6-7, pis. 4, 5, figs. 1-3. 1954 



(Fig. 11 M, p. 110) 



"Thallus endobiotic, prosporangium oval to elongate-oval, 8.6-23 \i 

 long and 5-1 1 [x high, arising as a swelling from the tip of the germ tube 

 of the zoospore. Sporangium inoperculate (?) variable in shape, spher- 

 ical or limoniform, 8-20 \x high and 6-8 \x broad, with a conspicuous 

 papilla up to 2 [i high. Distal half of sporangium wall thick and covered 

 with short rod-like markings. Empty zoospore case remaining on 

 akinete or carried up on wall of sporangium. Zoospore 2.5-3 u. in 

 diameter, content granular with several minute refractive globules. 

 Resting spore formation preceded by fusion of isogamous gametes, 

 one of which had previously come to rest and (?) germinated. Resting 

 spore endobiotic, oval to elongate oval, 8-26 p. long and 7-16 u. high, 

 with a thick smooth two-layered wall; content one or a few large 

 globules. A triangle of highly refractive material occurs at the point 

 of contact of the thickened thread from the gametes and the resting 

 spore itself. Resting spore directly transformed into sporangium on 

 germination" (Canter, be. cit.). 



Parasitic on akinetes of Anabaena affinis var. intermedia in the plank- 

 ton, Canter (be. cit.); Anabaena affinis var. intermedia, coll. Griffiths 

 (1925), Great Britain; Anabaena macrospora, coll. Fott, Canter (be. 

 cit.), Czechoslovakia. 



Because knowledge concerning sporangial discharge is lacking, Canter 

 only tentatively places this fungus in Rhizosiphon. It is believed here 

 that further observation of living material will validate assignment of 

 the species to this genus. 



APHANISTIS Sorokin 



Arch. Bot. Nord France, 2: 35. 1883 (separate) 



(Fig. 24 A-B, p. 396) 



Thallus endobiotic, monocentric, polyphagous, eucarpic, sterile part 

 consisting of a branched orunbranched isodiametric septate filament; 



