Spores of members of Choanephoraceae bear
hyaline appendages; the ultrastructure of spor-
angiospore ontogeny was published forZygor-
hynchus heterogamus(Vuill.) Vuill. (Edelmann
and Komparens 1994 ).
b) “Conidia” Versus True Conidia
The termconidiumhas often been applied to
the unispored propagules of several taxa in the
Mucorales, includingChaetocladium,Choane-
phora, and Cunninghamella.These so-called
conidia, however, are unispored sporangiola
in which a sporangiospore wall is deposited
inside the sporangiolar wall. True conidia
lack the sporangiospore wall and are only
formed by members of Zoopagomycotina (in
these subphyla).- Endospore-Forming Structures
a) Sporangia
The sporangium is a reproductive structure
characteristic of Mortierellales and Mucorales.
Sporangia contain between 100 and 100,000
endogenous sporangiospores, depending on
the species. The majority of mucoralean fungi
produce sporangia that are globose to obpiri-
form. Sporangia [Fig.8.4(30, 31, 33)] are formed
on the apex of the main sporophore or its
branches; a columella is usually present. The
region of the sporophore immediately below
the sporangium can be nonapophysate (con-
stricted), apophysate (expanded or hemiconi-
cal), or vesiculate (expanded and then
constricted); these sporangial types are illu-
strated by Zycha et al. ( 1969 ), Benjamin ( 1979 ),
and O’Donnell ( 1979 ). The sporangial wall can
be persistent [Fig.8.4(33)], deliquescent, or eva-
nescent (fugaceous), and it can be variously
colored. In Choanephoraceae [Fig.8.4(33, 34)]
the sporangial wall is persistent and has a longi-
tudinal suture or sutures where it splits to
release the spores in a droplet of fluid (Ingold
and Zoberi 1963 ). InPilaira(Mucoraceae) the
zone of weakness is present at the base of the
sporangium, and therefore the sporangial wall is
released as a unit along with many sporangios-
pores (Fuller 1978 ; Ingold and Zoberi 1963 ).b) Sporangiola
The sporangiolum is a small sporangium; it
has a persistent wall and is borne on a pedicel
or denticle. A pedicel arises from a sporophore
or fertile vesicle, whereas a denticle is pro-
duced only from a fertile vesicle(Benny 1995 ;
Benny and Benjamin 1975 , 1976 ). Sporangiola
are globose to obpiriform, apophysate or non-
apophysate, and can contain one [Fig.8.4(37)]Fig. 8.3Representatives of only order (Mortierellales) of
Mortierellomycotina. 23 .SporangiumofLobosporan-
gium transversale. 24. Sporophores and two-spored spor-
angia ofGamsiella multidivericata. 25. Several sporangia
ofModicella malleola. 26. Sporophores and sporangia of
unidentified species ofMortierella. 27. Zygospores of
unidentified species ofMortierellashowing heteroga-
mous suspensors (L¼large, S¼small). 23–25, 27.
Bar 100 mm. 26 .Bar¼ 500 mm
226 G.L. Benny et al.