226 A MANUAL OF THE PENICILLIA 



Penicillium fuscum (Sopp) n. comb. 

 Synonym: Citromyces fuscus Sopp, in Monograph pp. 120-122. Taf. 

 XIV, fig. 100; Taf. XXII, fig. 6. 1912. See also, Thom, 

 The PeniciUia, p. 180. 1930. 



Colonies on Czapek's solution agar growing slowly, attaining a diameter 

 of 2.5 to 3.0 cm. in 12 to 14 days at room temperature, cushion -hke, 1 

 to 2 mm. deep, spongy or fleshy, with surface often appearing wet in 

 localized areas, showing light radial furrows in narrow submarginal zones, 

 felted, showing some ropiness in central colony areas when viewed at low 

 magnifications, becoming velvety in age in narrow marginal zones and with 

 deep submerged mycelium extending 1 to 2 mm. beyond the edge of co- 

 nidial development (fig. 61D), medium sporing throughout, heaviest in 

 marginal and submarginal areas, at first olive-gray (Ridgway, PI. LI) 

 becoming deep grayish. olive to hair brown (R., PI. XLVI) in age; exudate 

 lacking; odor slight or indefinite; reverse uncolored or nearly so; conidio- 

 phores variable, arising mostly from aerial hyphae and usually not ex- 

 ceeding 100m in length by 2.0 to 2.5/x in diameter but occasionally longer up 

 to 150 to 200/x, conspicuously septate, with walls comparatively heavy, 

 light yellow-brown in color, smooth or finely roughened; penicilli variable, 

 ranging from fragmentary to strictly monoverticillate to irregularly 

 branched (suggesting the Divaricata), with two or more metula-like cells 

 borne terminally or at lower septa; sterigmata divergent, in small clusters 

 up to 6 or 8, not uncommonly in two's or three's and occasionally single, 

 mostly 6 to 9/x by 2.0 to 2.5)U (fig. GIF), with conidium-bearing tips defin- 

 itely constricted and comparatively long; conidia globose, at first color- 

 less, spinulose, becoming coarsely roughened with prominent dark tu- 

 bercles when mature, mostly 3.5 to 4.0ju or up to 4.5/x in diameter, olive- 

 brown in mass, borne in tangled chains up to 50 to 100/x in length. 



Colonies on steep agar growing more rapidly, about 4.0 cm. in 2 weeks, 

 with texture and color as described above but somewhat heavier sporing; 

 conidial structures as on Czapek. 



Colonies on malt agar spreading broadly, up to 6.0 cm. or more in 2 

 weeks, comparatively thin, not spongy, with surface appearing somewhat 

 velvety but characterized by abundant trailing and interlacing hyphae, 

 heavily sporing throughout (fig. 61E), in dark olive-green shades; conidio- 

 phores somewhat longer than on Czapek and more frequently branched 

 in the manner of the Divaricata. 



The above diagnosis is drawn primarily from NRRL 721 isolated from 

 Texas soil and sent to us in 1930 by Professor M. B. Morrow, University 

 of Texas. The strain is identified with Sopp's Citromyces fuscus primarily 

 upon the basis of its color, the character of its conidial structures, and its 

 large coarsely roughened conidia. The change of name is dictated by 

 inclusion of Wehmer's genus Citromyces in Penicillium (see p. 18). Correct 



