156 A MANUAL OF THE PENICILLIA 



In the series proper, Penicillium thomii Maire is the oldest, best known, 

 and most abundant species, apparently being world-wide in distribution. 

 A form approximating this species was reported and described as culture 

 No. 29, without a name, by Thom in 1910. Subsequent to this, Maire 

 (1917), investigating the fungi of North Africa, described a sclerotial form 

 as P. thomii and called attention to similarities between his species and 

 Thom's culture. The species as now recognized represents a common soil 

 type characterized by the production of pink sclerotia, often in sufficient 

 numl:)ers to characterize the colony. Penicilli are abundantly produced 

 upon most media, are strictly monoverticillate, and bear elliptical to sub- 

 globoss, smooth-walled conidia (fig. 43A). 



Van Beyma in 1937 described Penicillium sclerotiorum in terms which 

 clearly aligned it with P. thomii, a placement confirmed by examination of 

 the type strain. It differs from P. thomii primarily in producing almost 

 colorless sclerotia in limited clusters or 'nests' that are surrounded by loose 

 envelopes of bright orange-red mycelium. Such islands of brilliantly col- 

 ored mycelium vaay occur somewhat scattered throughout the colony, or 

 they may be massed together to form a continuous layer in which conidial 

 structvu'es occur either scattered or in small localized areas. The penicillus 

 (fig. 43B) is essentially like that of P. thomii. The species was originally 

 isolated in Java, but has since been obtained from other sources, mostly of 

 tropical or subtropical origin. It appears to be less widely distributed 

 than P. thomii. 



Penicillium lapidosum Raper and Fennell (1948) is based upon a culture 

 isolated by Williams, Cameron, and Williams (1941) from canned blue- 

 berries. The species is unusually heat-resistant. It is characterized b}' 

 its rapid growth, its abundant orange-brown sclerotia, and its sparse pro- 

 duction of conidial structures (fig. 43C) upon most substrata. Penicillium 

 mangini Duche and Heim (1931), a sclerotial species not recognized in this 

 Manual for reasons cited elsewhere (see p. 165), is regarded as possibly 

 approximating P. lapidosum. 



Two species comprise the Penicillium turhatum sub-series, namely: P. 

 lurbatum Westling and P. pusillum Smith. Both are characterized by 

 their failure to produce sclerotia upon Czapek agar and also their more 

 restricted growth upon this substratum. In these species, sclerotia are 

 softer and easily crushed. The degree of relationship between them and 

 the members of the P. thomii series proper is open to some question. How- 

 ever, they possess certain characters in common and it is believed that they 

 can be keyed here more satisfactorily than elsewhere. 



Penicillium thomii Maire, in Bui. Soc. Hist. Nat. Afrique du Nord. 8: 



189-192. 1917. See also, Thom, U. S. Dept. Agr., Bur. Anim. Ind., 



Bui. 118, p. 78. 1910; also The Penicillia, p. 173. 1930. 



