DESCRIPTIONS OF MEDICAL FUNGI

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Descriptions of Medical Fungi
Synonymy: Basidiobolus meristosporus Drechsler.
Basidiobolus heterosporus Srinivasan & Thirumalachar.
Basidiobolus haptosporus Drechsler.
Basidiobolus ranarum is commonly present in decaying fruit and vegetable matter, and
as a commensal in the intestinal tract of frogs, toads and lizards. It has been reported
from tropical regions of Africa and Asia including India, Indonesia and Australia.
RG-2 organism.
Basidiobolus ranarum Eidem
Morphological Description: Colonies are moderately fast growing at 30 O C, flat,
yellowish-grey to creamy-grey, glabrous, becoming radially folded and covered by a fine,
powdery, white surface mycelium. Satellite colonies are often formed by germinating
conidia ejected from the primary colony. Microscopic examination usually shows the
presence of large vegetative hyphae (8-20 µm in diameter) forming numerous round (20-
50 µm in diameter), smooth, thick-walled zygospores that have two closely appressed
beak-like appendages. The production of “beaked” zygospores is characteristic of the
genus. Two types of asexual conidia are formed, although isolates often lose their ability
to sporulate with subculture. Special media incorporating glucosamine hydrochloride
and casein hydrolsate may be needed to stimulate sporulation (Shipton and Zahari,
1987). Primary conidia are globose, one-celled, solitary and are forcibly discharged
from a sporophore. The sporophore has a distinct swollen area just below the conidium
that actively participates in the discharge of the conidium. Secondary (replicative)
conidia are clavate, one-celled and are passively released from a sporophore. These
sporophores are not swollen at their bases. The apex of the passively released spore
has a knob-like adhesive tip. These spores may function as sporangia, producing
several sporangiospores.
References: Strinivasan and Thirumalachar (1965), Greer and Friedman (1966),
Dworzack et al. (1978), McGinnis (1980), King (1983), Rippon (1988), Davis et al.
(1994), Jong and Dugan (2003), de Hoog et al. (2000, 2015) and Ellis (2005a).
20 μm
Basidiobolus ranarum showing thick-walled zygospores.