MONOVEKTICILLATA 225 



pointed; conidia globose, about 2.0 to 2.5m, rarely 3.0m in diameter with 

 walls conspicuously roughened, not adhering in long chains. 



Colonies on steep agar as described above but growing somewhat more 

 rapidly, slightly heavier sporing, and producing more abundant exudate; 

 penicilli as described above. 



Colonies on malt agar restricted, deeply floccose, up to 2 mm., not 

 furrowed, slightly heavier sporing (fig. 6 IB), appearing pale bluish gray 

 throughout, darkest in sub-central areas; penicilli as described on Czapek. 



Species diagnosis based upon Oilman and Abbott's original description, 

 upon Thom's records of their type and a second strain, isolated from a 

 peat bog by C. L. Shear (see Monograph, p. 177, 1930), and upon cul- 

 tural studies of NRRL 1748 received in 1940 from Professor Elizabeth 

 McCo}^ as a strain isolated by Professor E. M. Gilbert, in 1937, from 

 Honduras soil. 



Cultures presenting the cultural and morphological picture of this 

 species are not infrequsntly encountered among soil isolates. They are 

 maintained in culture with difficulty, however, and usuall}^ become sterile 

 or nearly so after a limited number of transfers. Forms presenting the 

 general aspect of the species, but known to represent atypical strains of 

 Aspergillus sydowi (Bain, and Sart.) Thom and Chiu'ch have been com- 

 monly observed. One such culture, obtained in 1930, and now maintained 

 as NRRL 719, fits reasonably well the description of Penicillium restrictum 

 when grown on Czapek's agar, but on malt agar develops as a fairlj^ typical 

 representative of A. sydowi. The latter species was among the most 

 abundant of all molds isolated from deteriorating military equipment in 

 tropical and subtropical areas. As submitted to us for identification, 

 many of these strains when grown upon Czapek agar produced conidia on 

 small and irregular penicillate structures, but, like NRRL 719, when grown 

 on malt agar often developed as typical .4. sydowi. The close relation- 

 ship of these two species was discussed by Thom and Raper in their "Man- 

 ual of the Aspergilli" (1945, p. 186). The validity of the species, P. 

 restrictum Oilman and Abbott, remains somewhat in doul)t, Init it is in- 

 cluded here to cover occasional isolates which cannot otherwise be satis- 

 factorily diagnosed. 



Citromyces griseus Sopp (Alonogr., pp. 119-120, Taf. XV, fig. 10-4: Taf. XXII, lig. 5. 

 1912) is regarded as possibly having represented some form approximating Peni- 

 cillium reslriclum Oilman and Abbott, but by description differs in producing smooth 

 conidia. A strain from the Centraalbureau received in March 1946, as F. griseuni 

 Olsen-Sopp originally from Professor Janke, Vienna, differs from P. restrictum as 

 described above primarily in producing thinner and less definitely floccose colonies 

 and conidia somewhat larger and coarsely roughened. 



