Chapter XI 

 THE ASPERGILLUS NIDULANS GROUP* 



Outstanding Characters 



Conidial heads short columnar, usually dark green with primary and 

 secondary sterigmata. 



Conidiophores smooth- walled, more or less browned, usually sinuate, 

 commonly less than 200m long and terminating in dome-like or hemi- 

 spherical vesicles. 



Conidia globose, echinulate, 3 to 4m in diame'ter. 



Perithecia usually present; ascospores purple-red in color and character- 

 ized by equatorial bands. 



Large, thick-walled, globose bodies, termed "hiille cells" (by Eidam), 

 forming an irregular layer around the perithecia. 



Aspergillus (Sterigmatocyslis) nidulans was described by Eidam in 1883. 

 Since that time the general type of organism covered by his diagnosis has 

 become fairly well-known and certain striking characters have become 

 recognized as defining a number of cosmopolitan strains or species, com- 

 monly referred to as constituting the Aspergillus nidulans group. 



The hiille cells of Eidam, first described in A. nidulans, appear also in 



various transformations in the A. versicolor, A. ustus, and A . flavipes groups, 



together with other common characters indicative of close relationship. 



They do not appear in the A . clavatus, A . glaucus, or A . fumigatus groups 



which are characterized by single sterigmata, nor do they occur in the 



sclerotium forming groups, A. candidus, A. niger, A. wentii, A. tamarii, A. 



flavus, and A. ochraceus. 



Group Key 

 I. Ascospores present. 



A. Ascospores smooth-walled. 



1 . Equatorial ridges two in number. 



a. Ridges 0.5 to 1.0m wide, margin entire. 



Conidial heads green A. nidulans (Eidam) Wint. 



Conidial heads white A. nidulans mut. alba Yuill 



b. Ridges 1.5 to 1.8m wide, margin entire 



A. nidulans var. latus Thom and Raper 



c. Ridges 3.0 to 4.9m wide, margin dissected, starlike 



A. variecolor (Berk, and Br.) Thom and Raper 



2. Equatorial ridges usually four in number 



A. quadrilineatus Thom and Raper 



B. Ascospores rough-walled A. rugulosus Thom and Raper 



1 Abridged from: Thom and Raper, The Aspergillus nidulans group, Mycologia, 

 Vol. XXXI, No. 6, 653-669, Nov.-Dec. 1939. 



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