DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 121
Malbranchea pulchella Sacc. & Penz.
Malbranchea species are soil fungi of worldwide distribution which microscopically may
resemble Coccidioides immitis/posadasii. Note: Culture identification by exoantigen
test or ITS sequencing is the method of choice for identification of C. immitis/posadasii.
RG-1 organism.
Morphological Description: Colonies are white to sulphur-yellow to ochre-brown
in colour, suede-like in texture, with a reddish-brown reverse, and often a reddish
diffusible pigment. Microscopic morphology shows typical hyaline, one-celled,
cylindrical, truncate, alternate arthroconidia produced in tightly coiled, terminal fertile
branches of the hyphae. Arthroconidia are released by lysis of the disjunctor cells.
These arthroconidia may be perceived as a yellow dust when released at maturity.
Key Features: Hyphomycete producing alternate arthroconidia with disjunctor cells.
References: Cooney and Emerson (1964), Sigler and Carmichael (1976), McGinnis
(1980), Rippon (1988), de Hoog et al. (2000, 2015).
20 µm
Malbranchea pulchella arthroconidia produced in tightly
coiled, terminal fertile branches of the hyphae.