Introduction to Fungi, Third Edition

ENTOMOPHTHORALES
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(2) Germination by repetition to form a secondary
conidiophore with a ballistosporic conidium.
This is essentially similar to the primary
conidium (Fig. 7.35a) and is produced under
conditions of high water availability and low
nutrient concentration. Secondary conidia may
germinate by further repetition or in other ways.
(3) Discharged ballistosporic conidia formed
in culture on certain media or located within
the gut of the frog may cleave to form many
endospores (sporangiospores, sometimes termed
meristospores), and these are released by dissolution
of the original conidial wall (Fig. 7.36a;
Dykstra, 1994).
(4) Germination under somewhat drier conditions
with a water activity at or below 0.995
stimulates the development of capilliconidia
or capillispores (Fig. 7.36c). The body of the
capilliconidium may cleave by transverse and
longitudinal septa to form endogenous segments
(endospores, meristospores) which are released
by breakdown of the wall of the capilliconidium
(Fig. 7.36d; Drechsler, 1956).
Capilliconidia are so called because they are
formed on long (over 0.3 mm), slender conidiophores.
The conidia themselves are spindleshaped
and apically beaked with a terminal
globose adhesive droplet or haptor. The material
making up the haptor is extruded through a
narrow channel within the beak of the conidium.
The droplet has unusual properties because it is
not affected by water but rapidly spreads out to
form a film when in contact with a solid surface
(Dykstra & Bradley-Kerr, 1994). The capilliconidia
are easily detached from their conidiophores
and may be dispersed by mites (Blackwell &
Fig 7.35 Basidiobolus ranarum. (a) Conidiophore from
culture. Note the conical columella and the swollen
vesicle with a line of weakness around its base.
(b) Primary conidium germinating to produce a
secondary conidiophore and ballistosporic conidium.
(c) Discharged conidium with remnant of the vesicle
attached. (d) Discharged conidium separated from the
remnant of the vesicle. (e) Conidium germinating directly
to form a septate mycelium.