DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 123
Microsphaeropsis arundinis (S. Ahmad) B. Sutton
Microsphaeropsis arundinis is a coelomycete that is ubiquitous in soil and fresh water.
It typically inhabits terrestrial plant hosts and has a well-known association with Aruno
donax, a garden escape weed known as ‘giant reed’ or ‘elephant grass’. M. arundinis
is an emerging cause of phaeohyphomycosis in cats and immunosuppressed humans.
RG-1 organism.
Morphological Description: Colonies growing slowly, with dense aerial mycelium,
initially greenish-grey, later becoming dark brown to grey-brown. Hyphae are septate,
pigmented, and irregularly shaped, with swollen segments up to 4 μm in diameter.
Pycnidia are subspherical, 250-350 μm in diameter; with a pseudoparenchymatous
wall composed of very densely packed cells that appear angular in cross section
(textura angularis). Conidiogenous cells ampulliform, up to 5 μm long. Conidia brown,
thick- and smooth-walled, cylindrical, 3.5-4.5 × 1.0-1.5 μm.
Key Features: Coelomycete, with ostiolate pycnidia, ampulliform conidiogenous cells,
and small, smooth-walled, brown, cylindrical conidia.
Molecular Identification: ITS and D1/D2 sequencing is recommended, especially as
it may take many weeks before pycnidia are produced in culture (Reppas et al. 2015).
References: Kluger et al. (2004), Pendle et al. (2004), Krockenberger et al. (2010),
Hall et al. (2013), Reppas et al. (2015), de Hoog et al. (2015).
a
b
Microsphaeropsis arundinis (a) culture and (b) pigmented
septate hyphae, with swollen segments.