THE ASPERGILLUS VERSICOLOR GROUP 187 



Aspergillus jamts Raper and Thorn, in Mycologia 36 : 55G-561, fig. 1. 1944. 



Species characterized by conidial heads of two distinct types, (1) large 

 white heads borne upon long conidiophores terminating in strongly clavate 

 vesicles and (2) smaller, dark green heads borne upon short conidiophores 

 with typically ovate vesicles (PI. I E and F, and V B). 



Colonies varying greatty in color and in texture depending upon the sub- 

 stratum and the temperature of incubation. Upon Czapek's solution agar 

 at 24° C. (fig. 54 A) colonies spreading irregularly, usually consisting of a 

 central floccose mass 1 to 2 mm. deep, pale yellow-buff in color, bearing few 

 and scattered fruiting structures surrounded by an irregular zone of 

 crowded fructifications with dark green heads occurring in a dense stand 

 adjacent to the substratum (fig. 54 D) and with numerous long-stalked 

 white heads projecting above this layer (fig. 54 C); reverse in dull yellow to 

 light brown shades. When incubated at 20° C, colonies more restricted, 

 less floccose and consisting almost exclusively of a dense stand of long- 

 stalked white heads with small green heads absent or developing only in age, 

 and arising from trailing aerial hyphae entwined among the white fruiting 

 structures. When incubated at 30 to 32° C. colonies close-textured, pre- 

 dominantly green but with central area commonly showing irregular patches 

 of massed hiille cells, buff to dull yellow in color. Conidial heads abundant 

 and consistently dark green in color. Reverse in dull brown shades. 



White conidial heads loose in texture (fig. 54 C), consisting of radiating 

 and divergent chains of conidia, eommonfy 150 to 200m in diameter, occa- 

 sionally larger. Conidiophores long, thin, mostly 2 to 2.5mm. in length by 

 8 to 10.5m in diameter, occasionally larger, erect, essentially uniform in 

 diameter throughout but often marked by numerous and irregularly spaced 

 constrictions, walls smooth, colorless, approximately 1 to 1.4/z in thickness. 

 Vesicles thin-walled, clavate (fig. 54 G), mostly 45 to 60m by 15 to 18m with 

 individual structures larger or smaller, entire surface loosely covered by 

 sterigmata as a rule, but often showing barren areas which may occupy any 

 part of the sterigmatic surface. Sterigmata in two series, primaries 7 to 

 10m by 3.5 to 4.5m; secondaries 6 to 8m by 2.5 to 3m. Conidia smooth, color- 

 less, globose to subglobose, mostly 2 to 2.5m, with maximum about 2.8m. 



Green conidial heads compact, radiate when young, becoming columnar 

 in age and often spreading into two divergent columns. Heads at first in 

 blue to blue-green shades near dark gobelin blue (Ridgwav, PI. XXIV), 

 becoming dark olive-gray in age (Ridgway, PI. LI), in size commonly rang- 

 ing from 60 to 75m in diameter to 200 to 300m in length. Conidiophores 

 erect, commonly 300 to 400m in length, by 6.5 to 8m in diameter, of uniform 

 thickness throughout, walls smooth, colorless or very faintly green, approx- 

 imately 1 to 2m thick, enlarging rather abruptly into an ovate vesicle. Ves- 

 icle thin-walled, variable in form and dimensions, but commonly ovoid (fig. 



