Colonies on agar Chapek rather limitedly growing, reaching on the 14th day 2.5–5 cm in diameter, felt or velvety, sometimes radially folded, grayish-white or, with intense sporulation, gray-green. Sporulation in gray-green or blue-green tones, uneven. By old age, the colonies become dark gray to almost black. The reverse is often yellowish, yellowish-green, brownish, violet-brown. Sometimes drops of unpainted or yellowish exudate are formed. On CYA, colonies reach a diameter of 2.5-3 cm in 7 days, radially folded, felt to velvety, with white, sometimes light yellow mycelium. Sporulation from mild to moderate, in gray-green or dirty green tones. Sometimes a colorless exudate is formed, sometimes a brownish water-soluble pigment is released into the medium. Reverse brown, orange, red-orange. On malt extract agar (MEA), the colonies are dense to woolly, with white or light yellow (sometimes pinkish) mycelium, sometimes with yellow or orange soluble pigment; reverse salmon pink, in the presence of soluble pigment - dark orange.
At 5 ° C, spore germination sometimes occurs, but large colonies usually do not develop. At 37 ° C, there is usually no growth on CYA, sometimes colonies are formed up to 1 cm in diameter.
Conidiophores in typical variants are two-tier, often branching incorrectly with numerous intercalary metulas in the form of single-tier brushes, smooth-walled, 50-200 microns long, with a bunch of metulas 8-15 microns long, sometimes slightly swollen at the apex. Phialides are flask-like, 6-8 microns long, with a short but pronounced neck. Conidia are spherical, 2.5-3.5 microns in diameter, prickly, in chains forming weakly formed columns.
Differences from close species
Penicillium canescens is usually distinguished by brighter pigmentation, as well as microscopically: rough legs of conidiophores and usually smooth-walled conidia.
Apparently, Penicillium janczewskii is a heterogeneous group in which several closely related species are hidden, however, as of 2018, a revision of this group (with recognition of independence, in particular Penicillium nigricans ) and the entire Canescentia section has not been published [1 ] .