Aspergillus conidia

Aspergillus is a common fungal genus of asexual ascomycetes with airborne conidia. In nature this genus typically occurs in the soil, and is especially common in moisture damaged indoor environments. Various species of Aspergillus have been implicated in human infections and other species are plant pathogens. Some Aspergillus species are known to produce mycotoxins under certain environmental conditions. Aspergillus conidia are known to be allergenic. Aspergillus and Penicillium are closely related fungi with similar conidia, and culturing is needed to identify the genus. On spore trap samples these are usually identified as Penicillium/Aspergillus-type spores. 

Aspergillus has a distinctive conidiophore that has a stalk and an inflated tip (called a vesicle) with phialides that produce the conidia. (In biserate conidiophores, the vesicle produces metulae, which in turn produce the phialides). The conidia are small 2-5 µm in size, spherical or ovoid, and may be  ornamented. Spores may be colorless or pigmented, and the ornamentation may pigment. Conidiophores and conidia can be found in Aspergillus cultures. Due to the similarity of Aspergillus and Penicillium conidia, they are identified as Penicillium/Aspergillus-type conidia on spore trap samples.