Aspergillus calidoustus is a species in the section Ustus, which grows at 37 °C (formerly called A. ustus, a species that fails to grow at 37 °C) and exhibits high minimal inhibitory concentrations to azoles. It is considered an agent of opportunistic infection.
Colonies can appear white and progress to brownish-yellow. Curved conidiophores and Hülle cells can be identified. The conidia are echinulated (spiny).