674 AQUATIC PHYCOMYCETES 



New records: Sparrow (1952b), Cuba; Sorgel (1952: 388), France. 



The description is based in the main on Kniep's Java No. 1 isolate. 



Emerson and Wilson (1954) demonstrated experimentally that this 

 "species" is a natural hybrid between AUomyces arbuscula and A.macro- 

 gynus (see p. 631). 



Allomyces macrogynus (Emerson) Emerson and Wilson 



Mycologia, 46: 429. 1954 

 (Fig. 40 C, p. 616) 



Allomyces javanicus var. japonensis Indoh, Sci. Rept. Tokyo Bunrika 



Daigaku, Sect. B, 4: 265, figs, lb, 24-28, 29 a-d, 30 a-c. 1940. 

 Allomyces javanicus var. macrogynus Emerson, Lloydia, 4: 135. 1941. 



Vegetative structures resembling AUomyces arbuscula; gametangia, 

 particularly on young hyphae, regular in shape and arrangement, the 

 primary and often the secondary ones very regularly paired, the males 

 always terminal, the females markedly elongate in the primary pairs, 

 often nearly cylindric, strikingly longer than the males (averaging about 

 twice and not seldom three to four times as long); female gametes, mean 

 diameter 9-12 pi; male gametes 4-6 a; resistant sporangia 32-85 \k long 

 by 26-53 \x wide, always formed in abundance even on young hyphae: 

 pits usually very fine, sometimes almost indistinguishable. (Slightly 

 modified from Emerson, 1941.) 



Indoh (1940), Japan; Sparrow, coll. W. R. Taylor (1943:426), 

 Venezuela. For other isolations see Emerson, 1941. 



There seems little doubt that Emerson's and Indoh's varieties were 

 established on identical forms. Emerson and Wilson (1954) show con- 

 clusively that Allomyces macrogynus should be segregated at the specific 

 level from the hybrid represented by A. javanicus. Furthermore, their 

 cytogenetical proof that A. macrogynus is one of the basic parental 

 types of that complex is decisive. 



So far as known Indoh had not prior to 1954 raised his variety to 

 specific rank. Hence, Emerson and Wilson's species name would be 

 valid because of the change of status from variety to species. 



As a result of Emerson and Wilson's (1954) work, it is anticipated 

 that the variety immediately following will prove to be of hybrid origin. 



