ASYMMETRICA-LANATA 443 



pronounced, "moldy"; colony reverse and surrounding agar in red-orange 

 shades, from English red to mahogany red to bay in age (R., PI. II); peni- 

 cilli as on Czapek's solution agar. 



Colonies on malt agar growing slowly, about 2.5 cm. in 10 days, deeply 

 floccose, white to very light cream, non-sporulating; odor not pronounced; 

 no exudate; reverse in orange-yellow shades near deep chrome through 

 cadmium yellow to raw sienna (R., PI. Ill), with agar in surrounding zones 

 in darker shades near mahogany red (R., PI. II). 



The species description is based primarily on NRRL 884 (Thom's No. 

 4733.6) received from Biourge as Penicillium aurantio-candidum Dierckx, 

 and presumably type. The species is represented also by a culture from 

 the Centraalbureau labelled P. aurantio-alhidum Biourge which had been 

 supplied by Thom in 1931, presumably his No. 4733.4. 



In Thom's Monograph (1930), Penicillium aurantio-candidum Dierckx 

 as described by Biourge (1923), and P. aurantio-alhidum Biourge were 

 considered as separate species although cultural similarities were observed 

 at the time. In the recultivation and comparison of these cultures inci- 

 dent to the present study the close relationship of the two forms has be- 

 come increasingly evident, the two cultures appearnig almost identical 

 culturally and microscopically. Both strains are characterized by colonies 

 which become orange to red or brown in reverse, and both are characterized 

 by an intense coloration of the substratum in the same or darker shades 

 which extends into the agar 2 to 3 cm. beyond the colony margin, and thus 

 produces conspicuous zones of reddish brown to mahogany color. This 

 distinctive coloration of the substratum is seen in all common substrata 

 but is most evident upon Czapek's solution agar with or without the ad- 

 dition of steep liquor. It appears to be characteristic of this species, and 

 also of P. aurantio-virens, a form probably closely related but assigned to 

 the P. cycloyium series because of its definitely fasciculate habit. 



Culture NRRL 887 (Thom's 4733.4), the t>T3e strain of Biourge's 

 Penicillium aurantio-alhidum, under continued laboratory cultivation in 

 our hands has become less characteristically lanose and now produces 

 restricted colonies, more or less floccose, often "wet", and characterized by 

 the production of limited conidia on irregular and atypical penicilli. The 

 characteristic pigment is no longer produced and the strain cannot now be 

 regarded as representative of the series. 



Occurrence and Significance 



Members of the Penicillium commune series appear to be comparatively 

 rare in nature. Thom (1910) isolated the type strains of P. hiforme and 

 P. commune from cheese but attributed no special significance to their 



