Skin scrapings mounted in 10% KOH showing pigmented brown to dark olivaceous (dematiaceous) septate hyphal elements and 2-celled yeast cells producing annelloconidia typical of Exophiala werneckii. (Courtesy of Dr J.W. Rippon, University of Chicago, U.S.A.).

Exophiala werneckii on Sabouraud's dextrose agar. Initially colonies are mucoid, yeast-like and shiny black. However with age they develop abundant aerial mycelia and become dark olivaceous in colour.

Microscopic morphology of Exophiala werneckii showing the typical 2-celled, pale brown yeast cells, with prominent darkly-pigmented septa, which act as annellides. Annellides may also arise from the hyphae. Annelloconidia are 1 to 2-celled, cylindrical to spindle-shaped, hyaline to pale brown and usually occur in aggregated masses.