AMERICAN 
JOURNAL OF BOTANY 
Vol. VIII May, 192 i No. 5 
ISOACHLYA, A NEW GENUS OF THE SAPROLEGNIACEAE^ 
C. H. Kauffman 
(Received for publication December 29, 1920) 
Isoachlya Kauffman gen. nov. Hyphae rather stout or slender. Zoo- 
sporangia formed from their tips, oval, pyriform, ventricose-clavate, the 
later ones (secondary) arising either by cymose or pseudo-cymose arrange- 
ment as in Achlya, or by internal proliferation as in Saprolegnia, both modes 
occuring earlier or later in the development of one and the same species, or 
frequently on the same main hypha. Zoospores diplanetic, as in Saproleg- 
nia, escaping and swarming separately, and after encystment swarming the 
second time before the formation of a germ tube. Oogonia terminal or toru- 
lose, occasionally intercalary. Oospores with centric contents, the spores 
filling the oogonium incompletely. Antheridia present or few to none. 
The genus is characterized and distinguished, in the main, by the 
presence of the cymose or Achlya mode of formation of secondary sporangia, 
coupled with diplanetic zoospores. The following species naturally fall 
within its boundaries : 
1. Isoachlya toruloides Kauffman and Coker sp. nov. 
2. Isoachlya paradoxa (Coker) comb. nov. Achlya paradoxa Coker. 
Mycologia 6: 285. 1914. 
3. Isoachlya monilifera (de Bary) comb. nov. Saprolegnia monilifera de 
Bary. Bot. Zeit. 16:629. 1888. 
Isoachlya toruloides Kauffman and Coker sp. nov. 
Hyphae rather slender and short, i8-20/i in diameter, later ones fre- 
quently smaller, straight and scarcely branched. Zoosporangia oval, 
pyriform, clavate-pyriform, more rarely elongated-pyriform, with a more 
or less distinct papilla; secondary sporangia, during the early and vigorous 
develo'pment, all cymosely arranged by successive basipetal formation, 
sometimes from the walls of earlier ones, later secondary sporangial initials 
appearing by internal proliferation as in Saprolegnia; zoospores diplanetic, 
capable of escaping and swarming separately, encysting after coming to 
^ After this paper was in the hands of the editor, a letter from Prof. W. G. Coker, of 
Chapel Hill, N. C, indicated that he was describing the same new genus and species. An 
exchange of data confirmed this supposition and hence it was agreed to publish them 
under joint authorship. The descriptions and figures to be given by Professor Coker 
have been examined by me, and I believe they apply to the same fungus. 
[The Journal for April (8: 179-230) was issued April 30, 192 1.] 
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