DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 155
Members of the genus Phoma have a worldwide distribution and are ubiquitous in
nature, with over 200 species having been described from soil, as saprophytes on
various plants, and as pathogens to plants and humans.
RG-1 organism.
Phoma Saccardo
Morphological Description: Colonies are spreading, greyish-brown, powdery or
suede-like and produce large, globose, membranous to leathery, darkly pigmented,
ostiolate pycnidia. Conidia are produced in abundance within the pycnidia on narrow
thread-like phialides, which are hardly differentiated from the inner pycnidial wall cells.
Conidia are globose to cylindrical, one-celled, hyaline, and are usually extruded in
slimy masses from the apical ostiole.
Molecular Identification: ITS, D1/D2, β-tubulin and 18S sequencing has been used
to identify Phoma species (de Gruyter et al. 2009, Aveskamp et al. 2010). Note: Public
sequence databases, particularly GenBank, contain many sequences from incorrectly
identified species, making identifications of coelomycetous fungi very difficult, without
confirmatory morphological studies.
Key Features: Coelomycete, ostiolate pycnidia producing masses of slimy, hyaline,
single-celled conidia.
References: Punithalingam (1979), McGinnis (1980), Sutton (1980), Rippon (1988),
Montel et al. (1991), Samson et al. (1995), de Hoog et al. (2000, 2015).
20 µm
Phoma spp. pycnidia with apical ostiole.