1 Spores formed in multispored sporangia (figs 68, 70,
72, 75, 76) or in few-spored sporangioles (figs 70, 73). 2
- Multispored sporangia and globose sporangioles absent.
Spores formed singly on terminal, lateral or
intermediate vesicles (figs 74, 79, 80, 82-86), or
in short chains (figs 77, 78, 81). 11
2(1) Sporangiophore stout, simple, with a subsporangial
swelling and a basal swelling buried in the substrate.
Sporangia tough walled, black, projected some distance
towards the light when mature, and sticking to whatever
they hit. _Pilobolus_ (fig. 76)
e.g. spores pale yellow, 8-10 × 5-6µm - _P. crystallinus_
spores orange, 12-20 × 6-10µm. - _P. kleinii_
- Sporangiophores not stout; sporangia not violently
discharged. 3
3(2) Sporangial wall black, tough, not readily broken when
touched. Sporangia with a sticky base, becoming
attached to whatever they contact after the marked
elongation of the white sporangiophores at maturity.
_Pilaira_ (fig. 75)
e.g. spores yellowish, 8-10 × 6µm - _P. anomala_
spores colourless, 11-13 × 6-8µm - _P. moreaui_
- Sporangial wall diffluent, spores readily removed in
a droplet, or fragile and then spores easily dispersed
by external violence. 4
4(3) Sporangiophores stiff and metallic in appearance,
growing towards the light and often to great length
(5-30cm). _Phycomyces_
e.g. spores 10.5-30 × 6.5-17µm; columella pyriform;
sporangiophores up to 30cm - _P. nitens_
spores 8-13 × 5-7.5µm; columella spherical or ovoid;
sporangiophores up to 30cm - _P. blakesleeanus_
- Sporangiophores white, not reaching extreme lengths. 5
5(4) Small lateral sporangia (sporangioles) present. 10
- Sporangioles absent. 6
6(5) Sporangiophores usually grouped, less often single,
connected by stolon-like hyphae. 7
- Sporangiophores arising singly, or if grouped then
lacking stolon-like hyphae. 9
7(6) Stolons joining groups of sporangiophores often with
rhizoids at the base of the group. 8
- Sporangiophores arising singly or in groups from
stolons, which may be 'rooted' at intervals along
their length, but rarely beneath the groups of
sporangiophores. _Absidia_ (fig. 71)
e.g. sporangiophores grouped, rhizoids poorly
developed; spores 2.5-4.5µm diam. - _A. corymbifera_
sporangiophores grouped, rhizoids strongly developed;
spores 2.5-3.5µm diam. - _A. orchidis_
8(7) Sporangiophores mostly unbranched. _Rhizopus_ (fig. 69)
e.g. spores irregularly angular-ovoid, 8-14 × 11µm
- _R. nigricans_
- Sporangiophores with a whorl of branches beneath the
main sporangium, each with a small columellate
sporangium. Spores 6-8.5µm. _Actinomucor elegans_
[Illustration: FIG. 68. _Mucor_, habit and detail of sporangium before and
after dehiscence. FIG. 69. _Rhizopus_, habit. FIG. 70. _Thamnidium
elegans_, habit and detail of sporangioles. FIG. 71. _Absidia_, habit. FIG.
72. _Mortierella_, habit and sporangiophore tip after sporangial
dehiscence. FIG. 73. _Helicostylum_, sporangioles. FIG. 74.
_Chaetocladium_, sporangioles. FIG. 75. _Pilaira_, sporangiophores before
and after elongation, and sporangium. FIG. 76. _Pilobolus_, sporangiophore.
FIG. 77. _Syncephalis_, habit, sporangiophore and merosporangia. FIG. 78.
_Piptocephalis_, habit and detail of final branch with head cell and
merosporangia. FIG. 79. _Oedocephalum_, habit and sporing head. FIG. 80.
_Rhopalomyces_, sporing head. FIG. 81. _Syncephalastrum_, habit and detail
of merosporangium. FIG. 82. _Coemansia_, habit, sporoclade with sporangia
and sporangium with spore inside. FIG. 83. _Kickxella_, habit and
sporoclade. FIG. 84. _Cunninghamella_, habit and fertile head. FIG. 85.
_Mycotypha_ (l) and _Ostracoderma_ (r) conidiophores. FIG. 86.
_Ballocephala_, habit of sporangiophores growing from parasitised
tardigrade, sporangiophore and sporangia.]
9(6) Sporangia often with pigmented walls, yellowish when
young, finally grey or black, with well marked columella
left after spore dispersal. Individual sporangiophores
observable with unaided eye, up to 20mm long.
_Mucor_ (fig. 68)
e.g. spores smooth, 7-8 × 2.5-4.5µm - _M. hiemalis_
spores smooth, 6-12 x 3-6µm - _M. mucedo_
spores asperulate, 5-8.µm diam. - _M. plumbeus_
(N.B. _Zygorhynchus_ would key out with _Mucor_. It is more
often isolated from soil, and is distinguished from _Mucor_
by the presence of zygospores with unequal suspensors)
- Sporangia white, without a columella, readily becoming
a spore droplet. Sporangiophores delicate, often only
200-400µm long. Fine, white, garlic-smelling mycelium
often present. _Mortierella_ (fig. 72)
e.g. spores 16-27µm diam, few in each sporangium;
sporangiophores ca 150µm, with short lateral branches
at right angles - _M. reticulata_
spores 6-10 x 4-6µm; sporangiophores 2-3mm high,
with ascending branches - _M. bainieri_
spores 4-10µm; sporangiophores richly branched - _M. candelabrum_
10(5) Sporangioles formed at the final tips of a densely
dichotomous system of branchlets, originating some
distance below a terminal sporangium (which may be
absent in young specimens). Sporangioles up to 25µm
diam., with up to 6 spores. Spores 8-12 × 6-8µm.
_Thamnidium elegans_ (fig. 70)
- Sporangioles either at the curved tips of slender
branches, or clustered in groups about halfway along
tapering branches which radiate from the sporangiophore
below the sporangium; the branch tips of the latter
give the fertile portion of the sporangiophore a
bristly appearance. _Helicostylum_ (fig. 73)
e.g. spores 8-17 × 3-7µm; sporangioles on short
secondary or tertiary branches; fertile region bristly
with sterile branches - _H. fresenii_
spores 6-8 × 4µm; sporangioles reflexed, on slender
primary or secondary branches; fertile region without
sterile branches - _H. pyriforme_
11(1) Spores formed in chains. 12
- Spores formed singly. 14
12(11) Sporangiophores regularly and repeatedly dichotomously
branched. Chains of 2-10 spores produced in small
groups, which may be wet or dry, on deciduous heads,
4-15µm diam. Parasitic on other fungi, mostly other
Mucorales. _Piptocephalis_ (fig. 78)
e.g. spores 4-5 × 2-3µm, in pairs; heads dry - _P. lepidula_
spores 5-6 × 2-2.5µm, in chains of 4-9;
heads dry - _P. cylindrospora_
spores 4-8 × 2-4µm, in chains of 3-5; heads dry;
sporangiophore without rhizoids - _P. freseniana_
spores 4-6 × 4-4.5µm, in chains of 3-6; heads wet;
sporangiophore with rhizoids - _P. repens_
spores 3-5 × 2-2.5µm, in chains of 3-5, heads wet; head
cell lyses, to leave only a fringe at the tip of the
very fine sporangiophore - _P. fimbriata_
- Sporangiophores simple or irregularly branched. 13
13(12) A large conspicuous fungus, macroscopically Mucor-like,
mycelium coarse. Sporangiophores with a distinct terminal
swelling with crowded spore chains. Spores usually 5-10
in a chain, globose to ovoid, 2-8 × 4-6µm.
_Syncephalastrum racemosum_ (fig. 81)
- Sporangiophores less conspicuous, 100-1000µm high, with
a 'holdfast' at the base attaching the sporangiophore to
the substrate. Mycelium very fine. Parasitic on other
Mucorales. _Syncephalis_ (fig. 77)
e.g. sporangiophores 100-200µm high, with three
'nodes' along their length; merosporangia often forked
at the basal cell; spores 8-10 × 6µm - _S. nodosa_
sporangiophores up to 750µm high; merosporangia
usually subdivided at their base into several branches,
each with 5-10 spores; spores 5-10 × 3-4µm - _S. depressa_
(N.B. _Oedocephalum_ spp. (fig. 79), the anamorphic states of
many dung fungi (esp. Ascobolaceae and Pezizaceae),
_Rhopalomyces_ (fig. 80), and some _Aspergillus_ spp. are
superficially similar to _Syncephalis_ at first sight).
14(11) Sporangia containing a single closely fitting elongated
spore, produced in serried ranks on one side of a
boat-shaped branch (sporoclade). 15
- Single-spored sporangia ('spores') globose, produced
singly or if in groups not on sporoclades. 16
15(14) Sporoclades lateral. Sporangiophores usually yellowish.
(No parasitism has been demonstrated, but in culture
grows much better in the presence of the white,
garlic-smelling _Mortierella_ spp.). _Coemansia_ (fig. 82)
e.g. spores 6-11µm long; sporoclades spirally arranged
around the axis - _C. erecta_
spores 16-18µm long; sporoclades formed on one side of the
axis, causing it to curve to one side - _C. scorpoidea_
- Sporoclades produced in a terminal verticil.
Sporangiophores shining white.
_Kickxella alabastrina_ (fig. 83)
16(14) Spores produced in clusters below the apex of the final
branches of a compound, often trifid, branching system
which is given a bristly appearance by the projecting
tips. Superficially similar to _Thamnidium_ or
_Helicostylum_. Capable of parasitising, and growing
much better in association with, other Mucorales.
_Chaetocladium_ (fig. 74)
e.g. spores smooth, 4-6µm diam. - _C. brefeldii_
spores echinulate, 6.5-9.5µm - _C. jonesii_
- 'Spores' not produced in subterminal clusters, but
terminally on lateral vesicles, or over the surface of
swollen fertile regions of the sporangiophore. 17
17(16) Sporangiophores up to 250µm high. Lateral vesicles
numerous, each producing a single 'spore', which is
projected when mature. Parasitic on tardigiades.
_Ballocephala_ (fig. 86)
- Sporangiophores visible with the unaided eye. Spores
produced on swollen parts of the sporangiophore. 18
18(17) Sporangiophores branched, with more or less globose
terminal fertile regions. Spores dry and powdery,
yellowish or pinkish in mass. _Cunninghamella_ (fig. 84)
e.g. spores smooth, ovoid, 18-22 × 10-14µm or
globose, 8-10µm diam. - _C. elegans_
spores echinulate, ovoid, 8-12µm - _C. africana_
- Sporangiophores unbranched, fertile portion 200-300 ×
15-20µm. Fertile region terminal only, cylindrical.
Spores smooth, greyish in mass, 2-4µm diam.
_Mycotypha microspora_ (fig. 85)
(N.B. _Ostracoderma epigea_ (fig. 85), the anamorph of
_Peziza astracoderma_, which occurs on paper and sometimes
dung and highly organic substrates, was originally described
as _Mycotypha dichotoma_. The fertile regions are cylindrical
but multiple as the result of several close dichotomous
divisions at the base of the fertile portion).