BIVERTICILLATA-SYMMETRICA 641 



Colonies on malt agar spreading broadly, up to 5.5 to 6.0 cm. in 12 to 

 14 days, plane (fig. 163B), heavily sporing throughout, in dark yellow-green 

 shades near Lincoln green to dusky olive green (R., PI. XLI) ; conidiophores 

 arising primarily from the substratum, less commonly from trailing or 

 ascending hyphae, mostly about 200m long, but ranging from 100 to 300m 

 or more by about 2.5 to 3.0m in diameter, with walls commonly roughened; 

 penicilli comparatively short, consisting of a terminal verticil of metulae 

 bearing clusters of somewhat divergent sterigmata, but typical of the Bi- 

 verticillata-Symmetrica; metulae occurring in verticils of 5 to 9, each bear- 

 ing a crowded cluster of 5 to 7 sterigmata with finely granular walls and 

 with strongly tapered conidium-bearing tips; conidia globose to subglobose, 

 3.0 to 3.5m in diameter, conspicuously echinulate, dark olive green in mass, 

 occurring in loosely parallel or tangled chains 100 to 150m in length. 



Species description based upon a number of strains received from Pro- 

 fessor William H. Weston, Harvard University, as unidentified cultures 

 isolated from canvas and other materials infected during exposure tests in 

 Florida. NRRL 2129 and NRRL 2130 are representative. The species 

 is regarded as new since careful examination of the literature has failed to 

 reveal anj^ described form which produces globose and conspicuously rough 

 conidia and strongly roughened conidiophores in colonies with deep red 

 colors in reverse. 



The species name is taken from the Latin aculeatus (meaning "prickly"), 

 and is applied because of the conspicuously echinulate character of conidia, 

 and the roughened walls seen in conidiophores, metulae, and even sterig- 

 mata on malt agar where the species makes its maximmn development. 



Penicillium aculeatum is tentatively assigned to the P. purpurogenimi 

 series. Such placement is based upon two primary considerations: (1) 

 colonies are more or less restricted on Czapek and steep agars and in re- 

 verse produce a rich red to purple-red coloration, and (2) colonies on malt 

 agar are broadly spreading, heavily sporing throughout, dark yellow-green 

 in color, and essentially velvety. It differs from the other members of this 

 series in producing conidial structures with walls often roughened and with 

 conidia strongly echinulate and globose rather than elliptical to subglobose. 

 Elements of the penicillus are usually shorter and tend to be divergent 

 rather than closely parallel. In this latter characteristic the species re- 

 sembles P. verruculosum Peyronel (see p. 621), which likewise produces 

 rough globose conidia. The comparatively short, broad penicilli are sug- 

 gestive of the P. herquei series, but the species shows little additional evi- 

 dence of relationship in that direction. Penicillium aculeatum is separated 

 from the P. funiculosum series by an absence or limitation of funiculose 

 hyphae. It is separated from the P. rugulosum series by the production 

 of abundant red to purple-red color in colony reverse, and by the character 



