116 A MANUAL OF THE ASPERGILLI 



often inconspicuous, walls smooth except for minute roughness along 

 equatorial ridges (fig. 27 B). Conidial heads generally abundant, numerous 

 in localized areas or scattered thinly over the colony, pale blue-green, 

 radiate, 150 to 250m in diameter; conidiophore smooth, colorless to orange- 

 brown, 500 to 750m in length, broadening to 14 to 16m where it passes into 

 the subglobose vesicular area of 25 to 35m diameter; sterigmata in a single 

 series 7 to 9m by 4 to 5m; conidia elliptical to subglobose, closely spinulose, 

 mostly 5 to 6.5m in long axis. 



Aspergillus ruber is represented in this study by NRRL Nos. 52, 53, and 

 others. Of 31 strains examined belonging to the whole series, 19 showed 

 colonies and microscopic characters that place them within the species 

 Aspergillus ruber as described above. Although the majority of strains 

 belonging to the A . ruber series produce plane colonies as noted in the de- 

 scription, occasionally strains may produce colonies more or less wrinkled. 



Culture NRRL No. 65 (figs. 29 C and 30 D) represents a subseries of 

 several strains that differ from the above not only in colony character upon 

 20 percent sucrose Czapek agar, as indicated in the preceding key, but also 

 in their growth upon media of lower concentration. These grow slowly 

 and poorly on Czapek (3 percent sucrose), potato-dextrose, and wort 

 agars, producing small raised colonies of 1 to 2 cm. in diameter bearing 

 neither normal conidial heads nor perithecia. 



Strain NRRL No. 70 (figs. 29 B and 30 C) produces abundant perithecia 

 only on very dry areas of the substratum in old cultures or on media con- 

 taining a sucrose concentration of 40 percent or more. In contrast to other- 

 strains, this fungus grows better upon media containing 4 percent agar than 

 the usual 1.2 percent agar, further establishing its xerophytic character. 



Strains such as NRRL No. 75 (figs. 29 D and 30 E), occasionally en- 

 countered, are predominantly conidial and characterized by rampant 

 hyphae bearing abundant conidial heads piled in floccose masses above the 

 substratum and upon the edges of the culture dish or tube. They thus 

 produce colonies markedly in contrast with the usual Aspergillus ruber 

 concept. But the character of their ascospores, together with the occur- 

 rence of occasional sectors in colonies of these strains showing the usual 

 mixture of perithecia and conidial heads, relates them definitely with A. 

 ruber. 



Strain NRRL No. 71 (fig. 30 B) represents a subsection of the series 

 in which conidial heads are abundant and generally arranged in fairly 

 definite zones and patches with loose clusters of perithecia irregularly and 

 conspicuously distributed among and above the grouped green heads. 

 These strains are further characterized by somewhat larger perithecia than 

 those of NRRL No. 52, being mostly in the range of 125 to 150m in diameter, 

 and by producing less red color in the colonies and in their reverse. 



