546 A Q UA TIC PH YCO M YCETES 



AMPHICYPELLUS Ingold 



Trans. Brit. Mycol. Soc, 27: 96. 1944 

 (Fig. 33 F-G, p. 564) 



Thallus monocentric, eucarpic, extramatrical, consisting of an oper- 

 culate sporangium and an apophysis with a rhizoidal system arising 

 from it; only the tips of the rhizoids entering the substratum; zoospores 

 finally delimited in a vesicle formed upon the dehiscence of the oper- 

 culum; resting spore not observed. 



A monotypic genus, members occurring on planktonic species of 

 Ceratium and Peridinium. 



Although the generic description states that the fungus is operculate, 

 the actual method of discharge was not seen by Ingold. Canter, who 

 has observed considerate material of Amphicypellus, states (comm., 

 1954) that she believes it to be inoperculate and to possess a type of 

 sexuality precisely like that in Rhizoclosmatium. R.A. Paterson (comm.), 

 however, who recently studied abundant material in Michigan, has 

 found sporangial discharge to be constantly operculate. Furthermore, 

 the zoospores in his material were simultaneously delimited in a vesicle 

 formed at the sporangial orifice. Here they underwent a period of motil- 

 ity before being liberated, as is typical for species of Chytriomyces. 

 Although the two genera strongly resemble one another, there are several 

 points of difference. Amphicypellus is constantly apophysate, only the 

 tips of its rhizoids enter the substratum and these always arise later- 

 ally from the apophysis, final cleavage of zoospores occurs in the vesicle. 

 In Chytriomyces, the apophysis is evidently not a constant feature, the 

 rhizoids are entirely endobiotic (in some species, for example the non- 

 apophysate C. appendiculatus, their position is not clear) and may arise 

 from any position on the apophysis and the zoospores are completely 

 formed at the time of discharge into the vesicle. No resting spore has 

 been found in Amphicypellus. It is epibiotic in Chytriomyces. 



Pertinent information necessary for the proper disposition of this 

 genus was too late in forthcoming to place it in the key to genera. 



Amphicypellus elegans Ingold l 

 Trans. Brit. Mycol. Soc, 27: 96, figs. 1-3, pi. 9. 1944 

 Sporangium spherical, 6 16 ;jl in diameter, with a globose, 3-5 [i 

 1 See Paterson in Mycologia, 50:91. 1958. 



