MONOVERTICILLATA 175 



In addition to such interspecies variation, other strains have been stud- 

 ied which merge Penicilliwn frequentans Westhng almost imperceptibly 

 into P. spinulosum Thom and P. purpurrescens (Sopp) n. comb. The 

 latter species is distinguished chiefly by its large, heavy-walled, and 

 coarsely roughened conidia, and by the prodviction in most strains of a 

 definite reddish purple pigmentation in the colony reverse. Penicillium 

 spinulosum, on the other hand, is typically characterized by colonies of 

 looser texture, with trailing hyphae usually abundant, and conidiophores 

 less consistently erect and often arising from the aerial growth; conidia 

 are spinulose and more definitely roughened than in P. frequentans but 

 are not coarsely roughened as in P. purpurrescens. 



The following species, described by other authors, are believed to be 

 inseparable from Westling's Penicillium frequentans. 



Citromyces albicans Sopp (Monograph, pp. 128-129, Taf. XIV, fig. 101; Taf. XXII, 

 fig. 10. 1912), from the author's figures and description, represents some member of 

 the Penicillium frequentans series. The name was based upon the presence of over- 

 growths of white mycelium, a character that is hardly diagnostic. (No one has 

 reported the species since Sopp's work was published). 



Penicillium auraniio-brunneum Dierckx (Soc. Scientif. Bruxelles 25: 86. 1901; 

 also, Biourge, La Cellule 33: fasc. 1, pp. 309-311; Col. PI. IX and PI. XV, fig. 85. 

 1923) was described by Biourge as rapidly spreading, somewhat wrinkled, gray-green 

 or blue-green to dark olive green, with colonies yellow toward reddish or orange- 

 brown in reverse, conidiophores unbranched, with all walls smooth, conidia globose 

 and about 3.0 to 3.5^. Thom's observations (1930, p. 218) on Biourge's type were 

 generally confirmatory, and he expressed the belief that the species differed suffi- 

 ciently from P. freguentans to be fairly readily separated. Re-examination in our 

 current study of the type strain, NRRL 766, a culture from the Centraalbureau as 

 from Biourge, and three additional cultures previously identified as P. aurantio- 

 brunneimi, shows conidiophores and conidia usually finely granular and reveals no 

 reliable bases for separation from P. frequentans in the broad sense that the later 

 species is considered here. 



Penicillium candido-fidvum Dierckx as described and illustrated by Biourge 

 (Monograph La Cellule 33: fasc. 1, pp. 275-277; Col. PI. X and PI. XVII, fig. 98. 

 1923) and as observed and reported by Thom (1930, pp. 218-219) differs little, if at 

 all, from P . frequentans except for the more frequent appearance of branched conidio- 

 phores. Colonies of the type strain were reported by the latter to be broadly spread- 

 ing, velvety, dull green, up to 400 to 500m deep, umbonate in central areas, with 

 reverse becoming yellowish to brown in age, sterigmata 8 to 10^ long, and conidia 

 mostly 3.0 to 3.5ai (wall character not given). The type strain (NRRL 769), as main- 

 tained in this laboratory, no longer meets the colony description as given by Thom 

 (1930) but now develops as a rather restricted, closely wrinkled, umbonate colony 

 producing abundant conidia only in the central area; colonies and fruiting structures 

 on malt agar, however, agree fairly well with representatives of the P. frequentans 

 series. Basing judgement primarily upon earlier rather than current observations, 

 we believe the species should be regarded as synonymous with P .frequentans Westling. 



