BIVERTICILLATA-SYMMETRICA 639 



NRRL 1180, received from Dr. G. A. Ledingham in 1937, is representative 

 of occasional strains which differ from the species in being less deeply pig- 

 mented in reverse. They differ further in producing colonies on Czapek 

 with a strong admixture of yellow pigmented hyphae. Details of the 

 penicillus and measurements of cellular elements are typical of the species. 

 Cultures of this type, in which a yellow-green colony is associated with a 

 red reverse have, in the past, been commonly assigned to Thom's (1930) 

 "PenicilHum luteum series — non-ascosporic." They may be regarded as 

 transitional between P. rubrum Stoll and P. variabile Sopp, as the latter 

 species is understood and presented in this Manual. 



Penicillium aculeatum Raper and Fennell, in Mycologia, 40: 

 535-538, fig. 10. 1948. 



Colonies on Czapek's solution agar growing restrictedly (fig. 163A), 

 about 2 cm. in 12 to 14 days at room temperature, consisting of a tough 

 basal felt 1 to 2 mm. deep, variously buckled and wrinkled, irregular in out- 

 line, medium sporing and velvety in appearance in central colony areas, 

 developing yellow-green shades near celandine to artemisia green (Ridg- 

 way, PI. XLVII), often with a pinkish cast from a limited overgrowth of 

 red-pigmented hyphae and embedded droplets of exudate; growing margins 

 2 to 3 mm. wide, white to slightly pink, often appearing somewhat tufted 

 or funiculose; exudate abundant, almost uncolored to definitely vinaceous, 

 occurring in small droplets and often becoming overgrown by conidial areas 

 as these develop ; odor almost lacking ; reverse in vinaceous or purplish red 

 shades approximating mineral red to dark mineral red (R., PL XXVII) in 

 older areas, usually not strongly discoloring the surrounding agar; conidio- 

 phores arising primarily from the mycelial felt, short, commonly about 50m, 

 rarely up to lOOpt by 3.5 to 4.0/i, with walls appearing somewhat granular; 

 penicilli typically biverticillate and symmetrical (fig. 163C) but with frac- 

 tional or monoverticillate structures commonly produced; metulae 8 to 12/i 

 by 4.5 to 5.5/i, usually appearing definitely inflated; sterigmata 7 to 9^ 

 by 3.0 to 3.5)Lt, often appearing somewhat swollen; conidia globose to sub- 

 globose, 3.0 to 3.5)u in diameter, with walls comparatively heavy and con- 

 spicuously echinulate (fig. 163C), borne in loosely parallel or tangled chains 

 75 to 100m in length. 



Colonies on steep agar growing somewhat restrictedly but more rapidly 

 than on Czapek, radially furrowed with center somewhat raised, medium 

 sporing throughout, in dull yellow-green colors as above but with reduced 

 development of pink aerial hyphae and an almost complete absence of pink 

 exudate, growing margin about 1 mm. wide, white; reverse usually in 

 lighter shades than on Czapek; conidial structures generally intermediate 

 in pattern between those developed on Czapek and on malt agar. 



