DESCRIPTIONS OF MEDICAL FUNGI

Descriptions of Medical Fungi 189
Syncephalastrum racemosum Cohn
The genus Syncephalastrum is characterised by the formation of cylindrical
merosporangia on a terminal swelling of the sporangiophore. Sporangiospores are
arranged in a single row within the merosporangia. Syncephalastrum racemosum is the
type species of the genus and a potential human pathogen; however, well-documented
cases are lacking. It is found mainly from soil and dung in tropical and subtropical
regions. It can also be a laboratory aerial contaminant. The sporangiophore and
merosporangia of Syncephalastrum species may also be mistaken for an Aspergillus
species, if the isolate is not examined carefully. RG-2 organism.
Morphological Description: Colonies are very fast growing, cottony to fluffy, white to
light grey, becoming dark grey with the development of sporangia. Sporangiophores are
erect, stolon-like, often producing adventitious rhizoids, and show sympodial branching
(racemose branching) producing curved lateral branches. The main stalk and branches
form terminal, globose to ovoid vesicles which bear finger-like merosporangia directly
over their entire surface. At maturity, merosporangia are thin-walled, evanescent
and contain five to ten (up to 18) globose to ovoid, smooth-walled sporangiospores
(merospores). Maximum growth temperature 40 O C.
Key Features: Mucorales, producing sympodially branching sporangiophores with
terminal vesicles bearing merosporangia.
References: Domsch et al. (1980), McGinnis (1980), Onions et al. (1981), Rippon
(1988), Samson et al. (1995), de Hoog et al. (2000, 2015), Ellis (2005b).
a
30 µm
b
10 µm
Syncephalastrum racemosum (a) merosporangia and (b) merospores.
Antifungal Susceptibility: S. racemosum (Espinel-Ingroff et al. 2015a); MIC µg/mL.
No. 16
AmB 35 8 16 3 6 2
POSA 36 1 2 4 10 11 5 1 2
ITRA 26 4 3 5 7 4 1 2