204 INFECTIONS CAUSED BY MOLDS 



P. Pedrosoi is more variable than P. verrucosa in its manner of 

 sporulation. The eonidiophore is a lateral or terminal branch of 

 nearly uniform diameter which bears at its tip one or more conidia. 

 These arise as buds at the tip and each is capable of proliferation by- 

 budding to produce one or more secondary spores. These in turn 

 can produce tertiary spores, and so on. This results in an arborescent 

 system of branching chains of conidia. In such spore heads the first 

 spores formed are modified as the complex system develops so that 

 they become shield-shaped. This is the type of sporulation typical 

 of Cladosporium and the fungus has, indeed, been commonly classi- 

 fied in the genus Hormodendrum which is a synonym of Clado- 

 sporium. 



Most spore heads of P. Pedrosoi are small, and the chains of spores 

 are limited in length to two or three. In fact, branching chains of 

 spores are difficult to demonstrate, both because they may be actually 

 very few or lacking in the culture and because when present they 

 almost invariably break up when mounted for examination. Most 

 of the conidiophores bear, instead of branching chains of conidia, a 

 large number of spores which are sessile and clustered about the tip 

 and for some distance below it, forming a sort of sleeve of conidia. 

 Such conidiophores are characteristically crooked and gnarled near 

 the tip where the conidia are borne and, when the latter are shed, 

 show scars where the conidia were attached. Some of the conidia 

 may bear secondary spores. Various combinations of these two types 

 of sporulation are commonly observed in most strains. Carrion * has 

 grouped strains into named varieties characterized by the predomi- 

 nance of one or another type. 



A third type of sporulation which appears to be identical with 

 that characterizing P. verrucosa was first observed in P. Pedrosoi 

 by Carrion and Emmons,^- * who pointed out the significance of this 

 observation in elucidating the relationship between these two etio- 

 logical agents of one disease. The phialophores are rare in P. 

 Pedrosoi but have been found in practically all strains examined. 

 They are isolated or grouped in clusters on the mycelium, or they 

 are borne as integral parts of the Cladosporium type of spore head. 



Taxonomy. Three species are recognized, Phialophora verrucosa, 

 P. Pedrosoi, and P. compactuni.'' P. Pedrosoi, because of the vari- 

 ability in its manner of sporulation, has been variously placed in 

 the genera Hormodendrum, Trichosporium, Acrotheca, Fonsecaea, 

 Gomphinaria, Botrytoides, Hormodendroides, and Phialoconidio- 

 phora. Binford and coworkers ^ emended the genus Phialophora to 



