3^4 A MANUAL OF THE PENICILLIA 



crowded fruiting areas commonly become interlaced with those of adjacent 

 penicilli. 



Species diagnosis is based primarily upon the following cultures: NRRL 

 802 (Thorn's No. 4733.42), received in 1924, from Professor Biourge as his 

 No. 78, which is presumably type; NRRL 803, received in 1927, from Dr. 

 C. E. Burnside, apiculturist, as a common infection in brood combs; and 

 two cultures received as Penicillium corylophilum Dierckx from the Cen- 

 traalbureau in February, 1946. The species is also represented by NRRL 

 799, brought to our Laboratory in 1936 by Dr. Paul Simonart as Biourge's 

 culture (type?) of P. chloro-leucon Biourge. It is further represented by 

 XRRL 793 from Biourge, in 1924, as his type of P. ohscurum Biourge, and 

 a culture of like origin, bearing the same name, from the Centraalbureau 

 in June, 1946. 



Penicillium conjloykihmi is fairly abundant in nature and widely dis- 

 tributed. It is isolated occasionally from soil, and several strains have 

 been encountered recently among the molds submitted to us for diagnosis 

 by various groups of investigators studying the tropical deterioration of 

 military equipment. Among the latter are included strains from stations 

 in the South Pacific area, Panama, Florida, and elsewhere. 



The species is placed in the Penicillium citrinum series solely upon cul- 

 tural and morphological considerations. It differs from P. citrinum in a 

 number of particulars, notably in an absence of any yellow pigmentation 

 and in its inability to produce citrinin. 



Careful examination of the descriptions and published figures of Peni- 

 cillium corylophilum Dierckx, P. obscurum Biourge, P. chloro-leucon Bi- 

 ourge, and P. sumatrense v. Szilvinyi, fail to reveal any marked differences 

 in either cultural behavior or structural detail. For this reason, and in 

 the light of recent studies, it is our considered opinion that these species 

 were separated upon inadequate criteria. The differences originally ob- 

 served were probably not greater than those kno^^^l to exist among the 

 representatives of many other cosmopolitan species. The above descrip- 

 tion of P. conjlophilum Dierckx is sufficiently broad to include the following: 



Penicillium obscurum Biourge (Mouogr., La Cellule 33: fasc. 1, pp. 267-269; Col. 

 PI. VIII and PI. XIV, fig. 80. 1923) culturally and morphologically closely approxi- 

 mates P. corijlophilu77i Dierckx. Biourge himself suggested a close relationship 

 between these species and Thom (1930, pp. 251 and 255) failed to observe adequate 

 bases for separation. In the present study, a detailed comparison of cultural habits 

 and microscopic structures in Biourge's type for P. obscurum, NRRL 793 (Thom's No. 

 4733.91, received in 1924 from Professor Biourge as his No. 120), and representative 

 strains of P. corylophilum have been made, and we are forced to conclude that we are 

 dealing merely with different strains of the same species. Penicillium obscurum 

 Piourge, the most recently described, is therefore regarded as a synonym, 



