Synonyms: Cladosporium werneckii; Exophiala werneckii; Phaeoannellomyces werneckii
Hortaea werneckii is a common saprophytic fungus believed to occur in soil, compost, humus and on wood in humid tropical and subtropical regions and is the causative agent of tinea nigra in humans.
Morphological Description: Colonies are slow growing, initially mucoid, yeast-like and shiny-black. However with age they develop abundant aerial mycelia and become dark olivaceous in colour. Microscopically, colonies consist of brown to dark olivaceous, septate hyphal elements and numerous two-celled, pale brown, cylindrical to spindle-shaped yeast-like cells that taper towards the ends to form an annellide. Most yeast-like cells also have prominent darkly-pigmented septa. Annellides may also arise from the hyphae. Conidia are one to two-celled, cylindrical to spindle-shaped, hyaline to pale brown and usually occur in aggregated masses. Chlamydospores also present.
Key Features: Hyphomycete, two-celled yeast-like cells producing annelloconidia.
Molecular Identification: An ITS-primer specific for H. werneckii was developed by Abliz et al. (2003). ITS sequencing can also assist identification.
References: Mok (1982), McGinnis (1980), McGinnis et al. (1985), Rippon (1988), de Hoog et al. (2000), Abliz et al. (2003), Ng et al. (2005).
Conidia of Hortaea werneckii.