BIVERTICILLATA-SYMMETRICA 655 



lacking; odor not pronounced, slightly musty; reverse uncolored; conidio- 

 phores up to 300/i in length; penicilli as described on Czapek but generally 

 showing metulae and sterigmata slightly longer ; conidia in loosely parallel 

 chains up to 200iu in length. 



Colonies on Czapek 's solution' agar containing ammonium sulfate (3 

 g. /liter) as the nitrogen source approximating those on malt in rate of 

 growth, general texture, and in the abundance of conidial structures pro- 

 duced; conidial areas near Andover green (R., PI. XL VI I) showing a 

 limited development of sterile, yellow pigmented aerial hyphae in sub- 

 marginal areas; exudate lacking; odor indistinct; reverse uncolored; peni- 

 cilli as described on malt agar. 



Species description centered upon numerous strains isolated from various 

 sources, including deteriorating military equipment, dried egg powder and 

 soils. Also represented by several strains of unknown origin submitted for 

 identification. The species is represented in our Collection by NRRL 2121 , 

 isolated from moldy leather and submitted to us for identification by Dr. 

 T. C. Cordon, Eastern Regional Research Laboratory; NRRL 2122, iso- 

 lated from soil collected in Sweden and contributed by Professor Edy 

 Velander, Stockholm, and others. 



This species is placed in the Penicillium tardum series primarily because 

 of its very restricted growth upon standard Czapek's and steep agars con- 

 taining nitrate as a nitrogen source. The fact that the species grows 

 luxuriantly upon malt extract agar and upon Czapek's solution agar con- 

 taining ammonium nitrogen clearly demonstrates the presence of a nutrient 

 deficiency. Recognition of the species as new is based not upon its limited 

 ability to utilize nitrate nitrogen, but upon its failure to duplicate any 

 recognized form even upon media containing ammonium nitrogen where it 

 grows luxuriantly. The species is clearly different from P. tardum Thom: 

 penicilli are more consistent in pattern; conidia are smaller, less definitely 

 elliptical, thin-walled, and smooth; and colonies upon favorable media are 

 spreading, plane, heavy sporing, velvety, and zonate." 



The binomial, Penicillium diver sum (from the Latin diver sus) is based 

 upon the markedly different growth of this species upon different substrata. 



Penicillium diversum var. aureum Raper and Fennell, in Mj^cologia, 40: 



541-542, fig. 11. 1948. 



Colonies on Czapek's solution and steep agars duplicating those of the 

 species in color, texture, and rate of growth (fig. 165D; cf. 1G5A) ; producing 

 afairly dense stand of conidial structures which differ from the species in 

 showing metulae and sterigmata more numerous in the verticil and usually 

 somewhat shorter. 



Colonies on malt agar duplicating those of the species in rate of growth 



