A revision of the genus Rhizopus. I. The Rhizopus stolonifer-group and Rhizopus oryzae


Schipper, M.A.A.

Studies in Mycology 25: 1-19

1984


The genus Rhizopus Ehrenb. is revised, mainly using the strains maintained in the CBS culture collection. In the Rh. stolonifer group only two species are maintained, both with several varieties. The variable species Rh. oryzae is described. Numerous older taxa are treated as synonyms. Keys to the accepted taxa are provided.

Studies
in
Mycology,
No.
25
1
June
1984
A
revision
of
the
genus
Rhizopus
I.
The
Rhizopus
stolonifer-group
and
Rhizopus
oryzae
M.
A.
A.
SCHIPPER
Centraalbureau
voor
Schimmelcultures,
Baarn
SUMMARY
The
genus
Rhizopus
Ehrenb.
is
revised,
mainly
using
the
strains
maintained
in
the
CBS
culture
collection.
In
the
Rh.
stolonifer
group
only
two
species
are
maintained,
both
with
several
varieties.
The
variable
species
Rh.
oryzae
is
described.
Numerous
older
taxa
are
treated
as
synonyms.
Keys
to
the
accepted
taxa
are
provided.
Introduction
The
genus
Rhizopus
Ehrenberg
(1820)
was
based
on
Rhizopus
nigricans,
an
incorrect
name
change
for
Mucor
stolonifer,
which
was
earlier
described
by
Ehr-
enberg
(1818).
The
first
description
is
too
concise
for
recognition,
but
the
au-
thor's
figures
of
Rhizopus
nigricans
are
distinctive.
Vuillemin
(1902)
and
Lind
(1913)
subsequently
used
the
name
Rhizopus
stolonifer
(Ehrenb.:Fr.)
Vuill.
The
early
history
of
the
genus
was
first
reviewed
by
Zimmermann
(1871).
Possible
synonyms
of
the
type
species
were
listed
by
Fischer
(in
Rabenhorst,
1892).
Well
known
treatments
of
the
genus
are
those
of
Lendner
(1908),
Han-
zawa
(1915),
Zycha
(1935),
Zycha
et
al.
(1969),
Naumov
(1935/1939)
and
Inui
et
al.
(1965).
The
genus
Rhizopus
would
appear
to
be
quite
large
judging
from
the
number
of
species
described.
However,
in
the
past
species
differentiation
was
often
based
on
minor
differences,
e.g.,
the
abundance
of
sporulation,
or
characters
not
cur-
rently
used
in
the
Zygomycetes,
such
as
the
ability
to
grow
with
or
to
ferment
given
components.
Zycha
(1935)
and
others
reduced
the
number
of
species
consi-
derably.
The
taxonomic
decisions
in
the
monograph
of
the
genus
by
Inui
et
al.
(1965)
are
not
accepted
here.
Firstly,
their
use
of
the
term
"type-strain"
is
incorrect:
several
of
these
strains
clearly
do
not
originate
from
the
authors
of
the
species.
Secondly,
the
use
of
keys
combining
morphological
and
physiological
characters
is
not
current
in
zygomycete
taxonomy.
A
need
for
a
total
review
of
the
genus
was
felt,
expanding
the
investigations
of
Scholer
(1970)
and
Scholer
and
Milller
(1971)
on
potentially
human
patho-
genic
species
of
Rhizopus,
a
large
part
of
the
accepted
species.
Throughout
the
present
study,
reference
will
be
made
to
Scholer's
thorough
investigation,
SCHIPPER:
RHIZOPUS
1
especially
where
dealing
with
the
small-sized
species,
the
Rh.
microsporus-group.
Material
and
methods
For
the
present
revision
all
available
Rhizopus
strains
from
the
CBS
collection
were
investigated:
82
strains,
which
had
been
received
under
52
different
names.
The
study
mainly
covered
the
general
morphology.
Light
microscopy
of
water
preparations
was
augmented
with
scanning
electron
microscopy
(SEM)
of
spore
ornamentation,
particularly
in
the
Rh.
microsporus-group.
Basic
criteria
for
spe-
cies
delimitation
were
derived
from
mating
experiments.
Temperature
relations
were
also
established.
Physiological
characters
were
not
included.
Species
are
mentioned
as
synonyms
only
where
type
strains
were
available.
Several
Rhizopus
species
described
in
not
easily
accessible
Japanese
journals
were
judged
using
diagnoses
translated
by
Japanese
colleagues.
The
routine
medium
for
morphological
and
growth
studies
was
malt
agar
(MEA).
For
mating
experiments
various
media
were
used:
MEA:
c.
3.5%
glu-
cose,
PH
7;
PDA:
c.
2%
glucose,
PH
6.6;
cherry
decoction
agar
(ChA):
PH
3.8-4.6;
yeast
extract
agar
(YEA):
yeast
extract
4
g,
malt
extract
10
g,
glucose
4
g
per
liter,
PH
7.3.
Cultures
were
grown
in
90-mm
glass
petri
dishes
containing
15
ml
of
nutrient.
Growth/temperature
relations
were
established
as
radial
growth
(dishes
cen-
trally
inoculated
with
identical
pieces
of
expanding
zone,
10
mm
diam,
placed
upside
down).
Measurements
were
made
after
24,
48
and
120
h.
The
length
of
sporangiophores
was
taken
from
sporangiophores
borne
on
stolons,
not
from
single
ones
originating
from
an
aerial
hypha.
The
size
of
the
sporangia
was
measured
in
undisturbed
colonies
with
the
aid
of
a
stereomicros
-
cope.
Sporangiospore
shape
and
size
were
determined
in
watermounts
with
light
microscopy.
Sizes
of
sporangia,
columellae
and
zygospores
are
given
"up
to"
the
largest
of
a
continuous
series.
Rare
extremes,
not
connected
with
the
series
by
intermedi-
ate
measurements
are
given
between
brackets
(Schipper,
1975).
Sample
preparation
for
SEM
was
after
Samson
et
al.
(1979).
Zygospore
production
was
determined
in
colonies
flooded
with
water,
(a)to
prevent
the
spreadi
ng
o
f
s
p
orang
i
ospores
o
f
poten
ti
a
l
h
uman
pathogenic
species
through
the
air,
and
(b)
to
dissolve
sporangial
walls
so
that
zygospores
were
more
easily
recognized.
If
necessary
the
colonies
were
systematically
flattened
with
an
inoculation
needle.
Generic
description
and
delimitation
Rhizopus
Ehrenb.
Rhizopus
Ehrenb.
De
Mycetogenesi,
p.
198.
1820.
Sporangiophores
mostly
formed
on
stolons
opposite
rhizoids,
either
single
2
STUD.MYCOL.
25.
1984
or
more
often
in
clusters,
unbranched,
occasionally
divided
near
the
top,
bearing
multispored,
terminal
sporangia.
Sporangia
globose,
distinctly
columellate,
apophysate,
greyish
to
brownish
at
maturity.
Sporangiospores
(sub-)globose
to
ellipsoidal
and
angular.
Zygospores
covered
with
spines
or
warts,
formed
in
aerial
mycelium
between
non
ornamented,
isogamous,
opposite
suspensors.
Type
species:
Rhizopus
stolonifer
(Ehrenb.:Fr.)
Vuill.
Rhizopus
differs
from
Mucor
Mich.:Fr.
and
Phycomyces
Kunze:Fr.
by
having
stolons
and
rhizoids.
It
can
be
separated
from
Actinomucor
Shostakovich
by
dark-coloured
sporangia
on
unbranched
sporangiophores,
mostly
arising
from
well-developed
stolons
with
distinct
rhizoids,
and
from
Absidia
v.
Tiegh.
by
its
globose
to
hemisphaerical
sporangia
on
unbranched
sporangiophores
opposite
rhizoids.
Thermomucor
Subrahmanyam
et
al.
has
branched
sporangiophores,
and
Rhizomucor
(Lucet
&
Cost.)
Wehmer
ex
Vuill.
has
non-apophysate
sporan-
a
Fig.
1.
Schematic
representation
of
Rhizopus
groups.
a.
Rh.
stolonifer
group;
b.
Rh.
ory-
zae;
c.
Rh.
rnicrosporus
group.
SCHIFFER:
RHIZOPUS
3
Table
1.
Summary
of
diagnostic
characters
of
Rhizopus
groups.
stolonifer-group
oryzae
microsporus-group
rhizoids
complex,
well
devel-
medium
oped
sporangio-
1-3
(4)
mm
long
phores
sporangia
(150)
250-275
(300)
pm
in
diam
zygospores
black,
up
to
225
pm
in
diam
suspensors
(appr.)
equal
max.
growth
(33)
36°C
temp.
occurrence,
bi-
on
overripe
fruit
ology
simple
mostly
up
to
0.5
mm,
rarely
up
to
1
mm
up
to
100
pm
in
diam
reddish
brown,
up
to
90
(100)
pm
in
diam
unequal
over
45°C
agents
of
mucormyco-
sis
max.
1-2.5
mm
long
max.
diam
160-240
pm
brown,
up
to
140µm
in
diam
unequal
45°C
food
fermentors;
agents
of
mucormy-
cosis
QQc)
C4?
QPQP
PQ99
99
QQC?
C?f?
Fig.
2.
Shapes
of
columella
e
i
n
Rh
.
m
i
crosporus.
a.
py
r
if
o
rm;
b.
pyriform-ellipsoidal;
c.
ellipsoidal;
d.
(sub-
)globose
to
subglobose-conical.
gia
on
branched
sporangiophores
and
poorly
developed
stolons
and
rhizoids.
In
Table
1
and
Fig.
1
the
differences
between
the
recognized
groups
are
summar-
ized.
Key
to
the
groups
1
Sporangiophores
mostly
not
exceeding
0.8
mm
in
height;
rhizoids
simple;
sporangia
up
to
100
pm
in
diam;
usually
growth
at
45°C
Rh.
microsporus
-
group
Sporangiophores
often
more
than
1
mm
in
height;
rhizoids
with
secondary
branching;
sporangia
often
over
100µm
in
diam;
no
growth
at
45°C
2
4
STUD.MYCOL.
25.
1984
2
Sporangia
commonly
up
to
275
µm
in
diam;
no
growth
at
36°C
Rh.
stolonifer-group
Sporangia
not
exceeding
240
pm
in
diam
;
growth
at
36°C
Rh.
oryzae
RHIZOPUS
STOLONIFER-group
GENERAL
CHARACTERISTICS
AND
VARIABILITY
Asexual
structures.
Common
features
of
the
majority
of
the
strains
of
the
Rh.
stolonifer-group
are
the
following:
Rhizoids
well
developed.
Sporangiophores
mostly
up
to
about
2000
µm
in
length,
20-25
µm
diam;
sporangia
up
to
about
250
µm
in
diam;
length
of
co-
lumellae
slightly
more
than
half
the
sporangial
height,
the
larger
columellae
coni-
cal-cylindrical
in
shape,
mouse
grey
or
brownish;
terms
used
for
columella
shapes
are
explained
in
Fig.
2.
Sporangiospores
angular-subglobose
to
ellipsoi-
dal,
with
distinct
ridges
on
the
surface.
No
growth
at
33°C.
Rhizopus
stolonifer
var.
stolonifer
and
var.
lyococcos
(Ehrenb.)
Stalpers
&
Schipper
were
described
from
3-day-old
petri
dish
cultures
on
MEA
at
25°C.
As
Rh.
sexualis
(G.
Smith)
Callen
did
not
show
optimal
development
at
25°C,
data
on
the
strains
of
this
species
were
derived
from
colonies
grown
at
20°C
for
4
(var.
sexualis)
or
8
days
(var.
americanus
Hesseltine
&
Ellis).
The
effect
of
temperature
on
viability
of
sporangiospores
of
both
species
was
studied
by
Dennis
and
Blyham
(1980),
while
the
effect
of
humidity
on
formation
of
sporan-
giospores
on
strawberries
was
investigated
by
Harris
and
Dennis
(1980).
The
homothallic
species
Rhizopus
sexualis
resembles
Rh.
stolonifer
in
the
shape
and
size
of
its
sporangiospores,
but
differs
in
having
relatively
small
spor-
angia
(incl.
columellae)
and
small
sporangiophores.
Rh.
sexualis
var.
americanus
has
a
somewhat
different
sporangial
state,
but
should
be
regarded
as
a
close
relative
because
of
similar
zygosporic
stages
and
temperature
responses.
Zygospores.
The
species
of
the
Rh.
stolonifer-group,
both
heterothallic
and
homothallic,
produce
black,
relatively
large
zygospores.
The
ornamentation
of
the
outer
spore
wall
differs
widely
from
that
of
the
Rh.
microsporus-
and
Rh.
Table
2.
Occurrence
of
zygospores
in
contrasts
of
Rh.
stolonifer.
CBS
319.35
and
320.35
are
strains
of
var.
lyococcos.
x
=
positive.
CBS
Nr.
320.35
263.28
403.51
442.74
107.76
609.82
853.72
319.35
x x
x
347.49
x
x
x
x x
x
_
108.76
x
x
x
x x x
x
109.76
x
x
178.82
x
479.82
x
x
SCHIPPER:
RHIZOPUS
5
4
%.
i
f
raMIL
.6
..
4
.•
reP.P
lot
I
.
11.
1
0/
7
_
1
,0
4:
0•
7
•47-
/
-
.'":v•-
d
ate,
4
Anwirvii
S
,
.01111\
Plate
1.
Zygospore
ornamentation.
1.
Rh.
homothallicus,
CBS
336.62,
750
x
;
2.
Rh.
ory-
zae,
CBS
127.08
x
346.36,
850
x
;
3.
Rh.
stolonifer,
CBS
107.76
x
108.76,
500
x
;
4.
Rh.
sexualis,
CBS
336.39,
420
x
;
5.
Rh.
oryzae,
CBS
127.08
x
346.36,
1750
x
;
6.
Rh.
stolon
i
fer,
CBS
107.76
x
108.76,
1750
x
.
Micro
g
raphs
by
J.A.
Stalpers.
6
STUD.MYCOL.
25.
1984
oryzae-groups
(Plate
1).
Within
the
Rh.
stolonifer-group
morphological
differ-
ences
in
the
zygosporic
stages
are
found
in
the
size
and
shape
of
the
suspensor
pairs.
The
first
description
of
the
zygosporic
stage
of
Rh.
stolonifer
was
given
by
de
Bary
(in
de
Bary
&
Woronin,
1866)
in
cultures
on
fleshy
fruits
and
on
bread,
during
a
warm
period
in
early
summer.
Several
subsequent
finds
of
zygospores
were
from
spontaneous
cultures
on
sweet
potato,
etc.
Blakeslee
(1904)
demon-
strated
heterothallism
in
Rh.
stolonifer.
In
the
present
study
zygospores
(Fig.
3)
were
obtained
on
various
media
under
very
moist
conditions,
at
25-27°C.
However,
repeated
contrasts
under
seem-
ingly
identical
conditions
were
often
unsuccessful.
The
use
of
small,
tightly
closed
petri
dishes
(adviced
by
Blakeslee,
1904)
did
not
give
notable
improve-
ment.
In
addition,
the
degree
of
development
varied
in
successful
matings
of
{100
ttm
Fig.
3.
Zygospores
in
matings
of
Rh.
stolonifer.
a.
CBS
442.74
x
108.76;
b.
CBS
263.28
x
319.35;
c.
442.74
x
109.76;
d.
319.35
x
320.35;
e.
CBS
320.35
x
108.76.
SCHIPPER:
RHIZOPUS
7
the
same
partners.
Comparatively
small
and
seemingly
"unfinished"
zygospores
were
often
found;
well-developed
ones
were
comparatively
rare.
Even
the
larg-
est,
black
zygospores
were
irregular,
with
frayed
projections
and
slightly
angular
bodies.
The
addition
of
trisporic
acid
and
methyl
4-dihydrotrisporate
(both
kindly
supplied
by
Prof.
Dr.
H.
v.d.
Ende,
University
of
Amsterdam)
only
gave
a
slight
improvement.
The
occurrence
of
zygospores
is
summarized
in
Table
2.
The
tester
pair
was
CBS
107.76
(—)
and
108.76
(+)•
Gauger
(1977)
germinated
mature
and
immature
zygospores
as
well
as
imma-
ture
suspensors
of
mated
Rh.
stolonifer.
From
mature
zygospores
he
obtained
(+)
or
(—)
colonies,
from
immature
zygospores
(+),
(
)
or
(
±
)
colonies;
the
latter
segregated
into
(+)
or
(
—),
and
recovered
(
+
)
colonies
out
numbered
(—)
colonies.
Germination
of
immature
suspensors
yielded
colonies
of
the
pa-
rental
or
opposite
genotype.
Namyslowski
(1906)
described
a
homothallic
strain
of
Rh.
stolonifer
which
produced
zygosporic
colonies
from
single
vegetative
spore
isolations,
if
grown
under
favourable
conditions.
Many
parthenospores
and
incomplete
conjuga-
tions
were
also
observed.
Rhizopus
sexualis
is
a
homothallic
species,
resembling
Rh.
stolonifer
in
several
respects.
Callen
(1940)
contrasted
the
type
strain
of
Rh.
sexualis
with
(+)
and
(—)
strains
of
Rh.
stolonifer
and
obtained
"hybrid
zygospores"
in
both
cases,
though
most
abundantly
with
Rh.
stolonifer
(+).
Callen
did
not
regard
them
as
true
hybrids
but
only
as
"mixochimeres
with
an
association
of
partnership
of
nuclei."
Germination
could
not
be
obtained.
Schipper
(1978)
considered
Callen's
"hybrid-zygospores"
to
be
induced
parthenospores.
Induced
parthenospores
develop
from
one
gametangium
only,
as
lysis
of
the
fusion-wall
between
gametangia
does
not
occur;
consequently
these
products
need
not
indicate
relationships
or
specific
identities
of
the
strains
involved.
Hawker
and
Syrop
(1973)
established
that
zygospore
initiation
and
development
in
Rh.
sexualis
were
poor
at
temperatures
below
10°C.
According
to
Harris
and
Dennis
(1980)
zygospore
production
is
favoured
at
90%
relative
humidity
or
above.
Key
to
the
taxa
1
Zygospores
present
in
single-sporangium
isolates
2
Zygospores
absent
from
single-sporangium
isolates
3
2
Sporangia
more
than
150
pm
in
max.
diam
Rh.
sexualis
var.
sexualis
Sporangia
less
than
100
pm
in
max.
diam
Rh.
sexualis
var.
americanus
3
Sporangiophores
erect
Rh.
stolonifer
var.
stolonifer
Sporangiophores
partly
recurved
Rh.
stolonifer
var.
lyococcos
8
STUD.MYCOL.
25.
1984
DESCRIPTIONS
OF
ACCEPTED
TAXA
Rhizopus
stolonifer
(Ehrenb.:Fr.)
Vuill.
var.
stolonifer
Mucor
stolonifer
Ehrenb.
Silvae
Mycol.
berol.
p.
25.
1818;
Mucor
stolonifer
Ehrenb.:
Fr.
Syst.
mycol..3:
321.
1829
=
Rhizopus
nigricansEhrenb.—
De
M
ycetogen-
esi
p.
198.
1820
(name
change)
=
Rhizopus
stolonifer
(Ehrenb.:
Fr.)
Vuill.
Revue
mycol.
24:
54.
1902.
Rhizopus
artocarpi
Racib.
Paras.
Algen
Pilze
Java's
1:
11.
1900.
The
description
is
of
CBS
609.82:
Colony
whitish,
with
sterile
aerial
mycelium
and
black
spots
of
sporangia
and
dark
sporangiophores.
Rhizoids
well
developed.
Sporangiophores
(on
sto-
lons)
up
to
2000
x
20
pm,
brown,
in
groups
of
1-3
(occasionally
more).
Sporan-
gia
blackish,
powdery
in
appearance,
up
to
275
pm
in
diam.
Columellae
conical,
mouse-grey,
up
to
140
pm
in
height
(rarely
larger).
Sporangiospores
angular-
globose-ellipsoidal,
up
to
13
pm
in
length,
distinctly
striate.
No
growth
at
33°
C;
growth
and
sporulation
at
15-30°C.
MATERIAL
EXAMINED
CBS
263.28
(—);
CBS
322.35,
P.
Claussen,
orig.
G.
Linnemann;
CBS
347.49
(
+),
ex
tempeh,
E.E.
Siahaija;
CBS
403.51
(—),
Nagao
Institute,
Tokyo;
CBS
853.72
(—);
CBS
442.74
(—),
ex
coffee
ground;
CBS
107.76
(—),
E.
Muller
No.
2828
=
Scholer
M-9;
CBS
108.76
(+),
E.
Muller
No.
2836
=
Scholer
M-79;
CBS
109.76
(+),
E.
Muller
No.
2675;
CBS
609.82
(—),
ex
ragi;
CBS
126.83,
ex
ragi;
CBS
478.82
(+);
CBS
479.82
(+);
CBS
150.83
=
I
M
I
62010,
Rh.
artocarpi,
ex
Artocarpus
integer.
DISCUSSION
Strain
variability:
in
CBS
108.76
rhizoids
were
rather
small;
CBS
442.74
failed
to
grow
at
30°C;
CBS
126.83
was
almost
devoid
of
rhizoids,
poorly
sporulating,
with
"unfinished"
sporangiospores,
poorly
developed
at
27
°C
and
rather
diffi-
cult
to
subculture.
CBS
403.51
was
received
from
the
Nagao
Institute,
Tokyo,
as
authentic
for
Rhizopus
niveus
Yamazaki.
According
its
diagnosis
(Yamazaki,
1919)
Rh.
niveus
should
be
a
small-sized
Rhizopus
species,
but
CBS
403.51
was
large
from
the
time
it
was
received
in
1951.
Probably
somewhere
along
the
way
an
error
has
been
made;
the
name
Rh.
niveus
therefore
remains
doubtful.
Rhizopus
artocarpi
Racib.
(1900)
was
described
from
the
male
inflorescence
of
Artocarpus
sp.
Raciborski
found
zygospores
in
one
of
his
agar
cultures,
but
never
on
the
host
from
wich
the
strains
were
isolated.
The
suspensors
were
de-
scribed
as
equal
in
size,
90-120
pm
in
length,
conical,
widening
towards
the
zygospore
to
70
pm.
The
asexual
state
of
the
type
strain,
CBS
150.83,
is
indistin-
guishable
from
Rh.
stolonifer;
zygospores
were
not
produced.
Rh.
artocarpi
(Berk.
&
Br.)
Boedijn
is
a
later
homonym
based
on
Mucor
artocarpi
Berk.
&
Br.
(1873).
The
description
is
very
incomplete,
no
mention
is
made
of
zygospores.
Boedijn
(1958/59)
described
zygosporic
isolates
from
Artocarpus,
but
did
not
SCHIPPER:
RIIIZOPUS
9
determine
homo/heterothallism
of
the
isolates.
The
"swollen"
suspensors
give
an
incompleted
picture.
Rhizopus
stolonifer
(Ehrenb.:Fr.)
Vuill.
var.
lyococcos
(Ehr-
enb.:Fr.)
Stalpers
&
Schipper
Sporotrichum
lyococcos
Ehrenb.
Silvae
Mycol.
berol.
p.
22.
1818
=
Rhizopus
stolon-
ifer
(Ehrenb.:Fr.)
Vuill.
var.
lyococcos
(Ehrenb.)
Stalpers
&
Schipper
Stud.
Mycol.
24:
68.
1984.
Rhizopus
reflexus
Bain.
Etude
Mucorin.
p.
68.
1882.
MATERIAL
EXAMINED
CBS
319.35
(+),
CBS
320.35
(—),
F.
Zach;
CBS
117.43.
DISCUSSION
This
variety
is
distinct
from
var.
stolonifer
by
the
presence
of
recurved
sporan-
gia
and
smaller
sporangiospores.
For
a
discussion
of
the
synonymy
of
Sporotri-
chum
lyococcos
and
Rh.
reflexus
see
Stalpers
(1983).
According
to
the
first
description
of
Rhizopus
reflexus,
all
sporangiophores
were
recurved.
It
was
noted
that
Rh.
reflexus
showed
poorer
growth
than
Rh.
stolonifer
in
summer
but
better
development
in
winter;
this
might
point
to
a
slight
psychrophily
in
Bainier's
strain.
No
authentic
material
is
known
to
be
preserved.
The
above
strains
produce
both
recurved
and
erect
sporangiophores
and
have
temperature
responses
similar
to
those
of
Rh.
stolonifer.
The
strains
CBS
319.35,
320.25
and
117.43
produce
colonies
with
both
recurved
and
erect
sporangiophores,
under
various
conditions
of
temperature,
humidity,
light,
me-
dium
and
position
(normal
or
upside
down).
Colonies
originating
from
single
sporangia
produced
sporangiophores
of
both
types,
independent
of
the
condi-
tion
of
the
parent
sporangium.
Bainier
(1882)
noted
in
Rh.
reflexus
an
inequality
in
thickness
of
the
sporan-
giophore
wall
between
inner
and
outer
curvature.
This
seems
to
indicate
a
per-
manent
condition
and
not
just
a
transitional
stage.
In
microscopic
preparations
an
inequality
of
wall
thickness
was
observed,
though
not
restricted
to
the
re-
curved
area
but
also
at
alternating
sides
in
straight
parts
of
recurved
and
erect
sporangiophores.
This
seems
to
indicate
spiral
growth
comparable
to
that
of,
e.g.,
Phycomyces
blakesleeanus
Burgeff
(Oort,
1931;
Oort
and
Roelofsen,
1932)
and
Zygorhynchus
exponens
Burgeff
(Grehn,
1932).
Zycha
(1935)
synonymized
Rh
circinans
v.
Tiegh.
(1876)
and
Rh.
reflexus,
after
studying
one
of
the
Zach
strains.
According
to
the
original
diagnosis,
Rh.
circinans
is
a
small-sized
species
of
Rhizopus
with
strongly
recurved
sporangia.
The
available
strains
that
show
recurved
sporagiophores
are
much
larger,
close
to
Rh.
reflexus.
Rh.
circinans
is
of
doubtful
identity.
10
STUD.MYCOL.
25.
1984
Rhizopus
sexualis
(G.
Smith)
Callen
var.
sexualis
Mucor
sexualis
G.
Smith
Trans.
Br.
mycol.
Soc.
22:
252.
1939
=
Rhizopus
sexualis
(G.
Smith)
Callen
Ann.
Bot.,
N.S.
4:
791.
1940.
The
description
is
of
CBS
336.39:
Colony
whitish
(due
to
abundant
sterile
mycelium).
Rhizoids
few
and
small.
Sporangiophores
(on
stolons)
up
to
1500
x
20
pm,
brown;
dichotomous
top-
branching
occurs.
Sporangia
blackish,
powdery
in
appearance,
up
to
175
pm
in
diam,
occasionally
larger.
Columellae
conical-cylindrical,
up
to
100
pm
in
height,
mouse-grey.
Sporangiospores
angular-globose-ellipsoidal,
up
to
13(-15)
pm
in
length,
distinctly
striate.
Zygospores
(homothallic)
black,
up
to
150
pm
in
diam,
with
blunt
projections.
Suspensors
globose,
equal
or
nearly
so.
No
growth
at
30°C;
growth
and
sporulation
at
15-25°C.
MATERIAL
EXAMINED
CBS
336.39
(homothallic),
type
culture;
CBS
123.64
=
IMI
10348
(homothallic).
DISCUSSION
CBS
123.64
differs
by
the
production
of
slightly
larger
zygospores
(up
to
170
pm
in
diam)
and
optimal
development
at
15°C.
The
descriptions
of
the
type
strain
by
Callen
(1940),
Hesseltine
and
Ellis
(1961)
and
the
above
all
deviate
from
the
original
description
by
Smith
(1939)
in
having
larger
sporangia
and
columellae
and
wider
sporangiophores.
The
present
CBS
cultures
do
not
show
the
described
symmetrical,
bifurcate
zygophores.
Rhizopus
sexualis
(G.
Smith)
Callen
var.
americanus
Hesseltine
&
Ellis
Rhizopus
sexualis
(G.
Smith)
Callen
var.
americanus
Hesseltine
&
Ellis
Mycologia
53:
424.
1961.
The
type
strain,
CBS
340.62,
differs
from
the
var.
sexualis
by:
colony
irregular
in
outline;
sporangiophores
up
to
700
x
8
mm;
sporangia
up
to
75
pm
in
diam,
mostly
smaller;
columellae
subglobose-applanate,
up
to
30
pm
in
height;
zygo-
spores
up
to
225
pm
in
diam.
MATERIAL
EXAMINED
CBS
340.62
(homothallic),
type
strain
of
Rh.
sexualis
var.
americanus.
DISCUSSION
CBS
340.62
sporulates
poorly;
the
sporangial
apparatus
is
poorly
developed.
SCHIPPER:
RHIZOPUS
11
While
in
strains
of
the
var.
sexualis
zygospore
production
can
be
poor,
in
the
var.
americanus
it
is
the
prevailing
character.
The
supposition
that
the
produc-
tion
of
abundant,
large
zygospores
might
cause
a
dwarfing
of
the
sporangia
was
tested
by
trying
to
suppress
zygospore
production
by
means
of
light,
change
of
medium
and
temperature,
but
without
success.
Zygospore
production
was
strong
under
all
conditions
of
this
investigation.
RHIZOPUS
ORYZAE
Most
strains
of
Rh.
oryzae
were
isolated
as
active
components
in
the
produc-
tion
of
oriental
foods
or
alcoholic
beverages
in
Indonesia,
China
and
Japan.
Many
hardly
distinguishable
species
have
been
described
in
the
older
literature.
A
trend
towards
a
reduction
of
the
number
of
accepted
taxa
has
become
appar-
ent
since
Zycha's
(1935)
revision
of
the
genus.
Inui
et
al.
(1965)
divided
the
genus
into
sections
on
the
basis
of
temperature
responses.
Their
section
Oryzae
consisted
of
species
growing
well
at
37°C
but
not
at
45°C
in
Pfeffer's
solution.
Dabinett
and
Wellman
(1973)
used
numerical
methods
on
data
published
by
Inui
et
al.
(1965)
and
arrived
at
an
essentially
similar
classification.
Scholer
(1970)
regarded
the
species
available
for
the
present
study
all
as
syno-
nymous
with
Rhizopus
oryzae,
though
in
a
number
of
species
the
identity
could
not
be
established
with
certainty.
His
conclusion
is
confirmed
in
the
present
study,
based
on
a
detailed
analysis
of
the
morphology,
and
on
mating
experi-
ments.
GENERAL
CHARACTERISTICS
Common
features
of
most
strains
of
Rh.
oryzae
were:
rhizoids
medium
sized
(see
Fig.1),
sporangiospores
up
to
1000-1500
pm
in
length,
(10—)13-15(-20)
pm
in
width,
local
swellings
and
dichotomous
branching
were
present.
Sporangia
up
to
150-175
pm
in
diam.
Col
umellae
ellipsoidal
on
a
truncate
base,
mouse-grey
or
brownish.
Sporangiospores
angular,
subglobose
to
ellipsoidal,
with
ridges
on
the
surface,
up
to
8(-10)
pm
in
length.
No
growth
at
45°
C,
growth
at
40°
C.
Zygospores.
Namyslowski
(1906)
and
Lendner
(1908)
mentioned
the
occur-
rence
of
zygospores
in
cultures
of
the
type
strain
of
Rh.
nodosus.
These
were
dark
brown,
ay.
120-140(-180)
pm
in
diam,
with
conical
projections
and
borne
between
equal
or
unequal
suspensors.
Homothallic
zygospores
were
not
ob-
served
during
the
present
study
in
monospore
isolates
of
CBS
127.08,
which
is
probably
Namyslowski's
strain.
The
mating
partners
VKM
F-773(
+
) (
=
CBS
699.68)
and
VKM
F-774
(-)
(=
CBS
700.68),
first
designed
as
Rhizopus
oryzae
by
A.A.
Milko,
were
reidenti-
tied
by
Scholer
(1970)
as
Rh.
microsporus.
A
number
of
strains
were
contrasted
with
the
above
tester
pair
of
Rh.
microsporus,
with
the
aim
of
elucidating
mating
abilities
in
Rh.
oryzae.
One
response
was
observed:
CBS
346.36
x
CBS
700.68
(
—)
resulted
in
short
lived,
incomplete
mating
reactions.
This
determines
Rh.
oryzae
CBS
346.36
as
(+).
12
STUD.MYCOL.
25.
1984
In
random
test
contrasts
within
the
oryzae-group,
zygospores
were
obtained
in
CBS
346.36
x
CBS
127.08.
YEA
at
30°C
was
found
to
be
the
optimum
for
zygospore
production.
The
zygospores
were
reddish
brown
when
young,
then
brown,
stellate
with
conical
projections,
up
to
140
Itm
in
diam,
between
unequal
suspensors.
Subsequently,
all
other
strains
were
contrasted
with
CBS
346.36
(+)
and
CBS
127.08
(
-
).
Zygospores
were
obtained
in
CBS
346.36
x
112.07;
127.08;
110.17;
148.22;
257.28;
264.28; 266.30;
329.47;
382.52
and
285.55.
Rhizopus
oryzae
Went
&
Prinsen
Geerl.
?
Rhizopus
arrhizus
Fischer
in
Rabenh.
-
KryptFl.
1
:
233.
1892
=
Mucor
arrhizus
(Fischer)
Hagem
-
Unters.
Norw.
Mucorin.
p.
37.
1907/08.
Rhizopus
oryzae
Went
&
Prinsen
Geerl.
-
Verh.
K.
Akad.
Wet.,
Sect.
2,
4:
16.
1895.
Rhizopus
japonicus
V
uill.
-
Revue
mycol.
24:
49.
1902.
Rhizopus
tonkinensis
Vuill.
-
Revue
mycol.
24:
53.
1902.
Rhizopus
tritici
Saito
-
Zentbl.
Bakt.
ParasitKde,
Abt.
2,
13:
157.
1904.
Rhizopus
nodosus
Namysl.
-
Bull.
Acad.
Sci.
Cracovie
1906:
682.
1906.
Mucor
norvegicus
Hagem
-
Unters.
Norw.
Mucorin.
p.
39.
1907/08.
Rhizopus
batatas
Nakazawa
-
Zentbl.
Bakt.
ParasitKde,
Abt.
2,
24:
482.
1909.
Rhizopus
delemar
(Boidin)
Wehmer
&
Hanzawa
in
Hanzawa
-
Mykol.
Zentbl.
1:
77.
1912.
Rhizopus
kasanensis
Hanzawa
-
Mykol.
Zentbl.
1:
407.
1912.
Rhizopus
usamii
Hanzawa
-
Mykol.
Zentbl.
1:
408.
1912.
Rhizopus
formosaensis
Nakazawa
-
Rep.
Gov
.
Res.
Inst.,
Formosa
2:
46.
1913.
Rhizopus
maydis
Bruderlein
-
Contrib.
Etud.
Panif.
Mycol.
Mais
p.
77.
1917.
Rhizopus
liquefaciens
Yamazaki
-
J.
sci.
agric.
Soc.,
Tokyo
185:
153.
1918.
Rhizopus
hangchao
Yamazaki
-
J.
sci.
agric.
Soc.,
Tokyo
193:
8.
1918.
Rhizopus
pseudochinensis
Yamazaki
-
J.
sci.
agric.
Soc.,
Tokyo
193:
996.
1918.
Rhizopus
chungkuoensis
Yamazaki
-
J.
sci.
agric.
Soc.,
Tokyo
193:
990.
1918.
Rhizopus
shanghaiensis
Yamazaki
-
J.
sci.
agric.
Soc.,
Tokyo
202:
598.
1919.
Rhizopus
peka
Takeda
-
Rep.
Dep.
Indus.
Gov
.
Res.
Inst.,
Formosa
5:
48.
1924.
Rhizopus
thermosus
Yamamoto
-J.
Soc.
Agric.
For.,
Sapporo
17:
481.
1925.
Rhizopus
boreas
Yamamoto
-
J.
Soc.
Agric.
For.,
Sapporo
17:
493.
1925.
Rhizopus
fusifOrmis
Dawson
&
Povah
-
Science,
N.Y.
68:
112.
1928.
Rhizopus
suinus
Nielsen
-
Virchow's
Arch.
path.
Anat.
273:
859.
1929.
Rhizopus
achlamydosporus
Takeda
-
J.
agric.
chem.
Soc.
Japan
11:
905.
1935.
Rhizopus
bahrnensis
Takeda
-
J.
agric.
chem.
Soc.
Japan
11:
908.
1935.
Rhizopus
delemar
(Boidin)
Wehmer
&
Hanzawa
var.
minimus
Takeda
-
J.
agric.
chem.
Soc.
Japan
11:
910.
1935.
Rhizopus
javanicus
Takeda
-
J.
agric.
chem.
Soc.
Japan
11:
909.
1935.
Rhizopus
semarangensis
Takeda
-
J.
agric.
chem.
Soc.
Japan
11:
907.
1935.
Rhizopus
sontii
Reddi
&
Subrahmanyan
-
Trans.
natn.
Inst.
Sci
India
1.
1937
(nomen
provisorium).
Rhizopus
javanicus
Takeda
var.
kawasakiensis
Takeda
&
Takamatsu
-
J.
agric.
chem.
Soc.
Japan
28:
74.
1949.
The
description
is
of
CBS
112.07:
Colony
greyish
brown.
Rhizoids
brownish.
Sporangiophores
on
stolons
up
to
1500
pm
in
length,
occasionally
longer,
up
to
18
pm
in
width,
with
local
SCHIPPER:
RHIZOPUS
13
swellings,
brown,
single
or
aggregated
in
small
groups.
Sporangia
greyish
black,
powdery
in
appearance,
up
to
175
pm
in
diam.
Columellae
ellipsoidal
on
a
trun-
cate
base,
up
to
130
pm
in
height,
mouse-grey.
Sporangiospores
angular,
subglo-
bose
to
ellipsoidal,
with
ridges
on
the
surface,
up
to
8
pm
in
length.
Zygospores
(112.07
x
346.36
on
YEA
at
30°C)
reddish
brown
when
young,
then
brown,
stellate
conical
projections,
up
to
140
pm
in
diam;
suspensors
unequal.
No
growth
at
45°
C;
good
growth
at
40°
C.
MATERIAL
EXAMINED
CBS
112.07,
type
culture
of
Rhizopus
oryzae;
CBS
127.08,
probably
authentic
for
Rh.
nodosus,
P.
Lindner;
CBS
128.08,
authentic
for
Rh.
tritici;
CBS
120.12,
type
culture
of
Rh.
delemar;
CBS
110.17,
type
culture
of
Rh.
maydis;
CBS
147.22,
L.
Harter;
CBS
148.22,
F.
McFarland;
CBS
256.28,
B.
Koehler;
CBS
257.28,
type
culture
of
Rh.
formosaensis,
CLMR;
CBS
258.28,
type
culture
of
Rh.
hangchao,
CLMR;
CBS
259.28,
CLMR;
CBS
260.28,
type
culture
of
Rh.
liquefaciens,
CLMR;
CBS
264.28,
type
culture
of
Rh.
pseudo-
chinensis;
CBS
266.30,
type
culture
of
Rh.
fusiformis;
CBS
295.31,
type
culture
of
Rh.
suinus;
CBS
296.31,
W.
Butkewitsch;
CBS
385.34,
type
culture
of
Rh.
achlamydosporus;
CBS
386.34,
type
culture
of
Rh.
bahrnensis;
CBS
387.34,
type
culture
of
Rh.
batatas;
CBS
389.34,
type
culture
of
Rh.
chiuniang?
var.
isofermentarius;
CBS
390.34,
type
culture
of
Rh.
delemar
var.
minimus;
CBS
391.34,
type
culture
of
Rh.
javanicus;
CBS
393.34,
type
culture
of
Rh.
peka,
R.
Nakazawa;
CBS
395.34,
type
culture
of
Rh.
semarangensis;
CBS
321.35,
Rh.
kasanensis,
G.
Linnemann;
CBS
324.35;
CBS
346.36,
L.H.
Leonian;
CBS
278.38,
Boulard
5;
CBS
279.38,
type
culture
of
Rh.
sontii;
CBS
327.47
=
ATCC
4858
=
ATCC
4859;
CBS
328.47
=
ATCC
9374,
A.F.
Blakeslee;
CBS
329.47
=
ATCC
10260;
CBS
348.49,
K.B.
Boedijn
and
J.
Reitsma•
CBS
401.51
=
NI
1204;
CBS
402.51,
type
culture
of
Rh.
javanicus
var.
kawasakiensis;
CBS
404.51
=
NI
1206;
CBS
405.51
=
NI
1207;
CBS
406.51
=
NI
1208
(1152
on
label),
possible
type
culture
of
Rh.
usamu;
CBS
381.52
=
ATCC
11145,
H.C.
Murray;
CBS
382.52
=
ATCC
6227,
A.F.
Blakeslee;
CBS
330.53
=
IFO
5318,
type
culture
of
Rh.
boreas,
Y.
Yamamoto;
CBS
395.54,
L.
Ajello;
CBS
285.55;
CBS
286.55;
CBS
264.60;
CBS
372.63;
CBS
607.68,
H.
Frank.
DISCUSSION
The
influence
of
external
conditions
was
tested
using
CBS
112.07.
It
was
grown
on
MEA,
CMA
and
ChA
at
temperatures
between
15
and
36°C
with
intervals
of
3°C.
At
27°C
development
was
optimal
on
all
media
applied.
At
36°
C
growth
was
rapid,
but
after
4
days
the
relatively
short
sporangiophores
frequently
showed
large
swellings,
and
sporangia
were
often
defective
with
subg-
lobose
to
conical
columellae;
complete
sporangiospores
were
few
and
rather
small.
This
effect
was
most
pronounced
on
MEA.
At
33°C
after
4
days
develop-
ment
was
sligthly
better.
At
lower
temperatures
expansion
growth
and
sporula-
tion
decreased.
After
17
days
at
15°C
few
swellings
occurred
in
the
sporangio-
phores.
Sporangiophores
and
sporangia
were
found
to
be
smaller.
Of
the
three
media,
colonies
on
MEA
were
most
sensitive
to
unfavourable
temperature
con-
ditions
with
regard
to
sporulation.
Usually
the
maximum
growth
temperature
was
reached
abruptly;
minimum
temperatures
were
not
determined.
The
additional
strains
of
the
species
showed
variability
in
all
mentioned
char-
acters.
Rhizoids,
usually
abundant,
were
rare
in
a
few
strains.
Sporangiophores
were
found
to
vary
from
750
to
1500(-2000)
pm
in
max.
length.
Sporangia
varied
from
100
(125)
to
200
pm
max
diam.
Columellae
ellipsoidal
in
shape
were
not
found
in
all
strains;
in
a
number
of
strains
the
larger
collumellae
were
subglobose
14
STUD.MYCOL.
25.
1984
to
conical.
Sporangiospores
were
found
to
vary
between
6
and
10(-18)
pm
in
max.
length.
The
great
majority
of
the
strains
grew
well
at
40°C,
though
occa-
sionally
the
turf
was
rather
low.
A
few
strains
deviated
in
their
temperature
response.
CBS
381.52
did
not
grow
at
36°C
and
produced
a
flat
colony
at
33°
C;
it
is
unknown
whether
the
strain,
which
was
used
for
oxydation
of
steroids,
has
been
genetically
manupilated.
CBS
259.28
produced
very
small
colonies
at
40
and
36°C,
growth
was
good
at
33°C;
the
strain
sporulated
poorly,
and
spor-
angiospores
were
variable
in
size.
CBS
390.34
grew
slowly
at
40°C,
while
good
growth
occurred
at
36°C;
CBS
386.34
showed
slightly
abnormal
hyphe
at
40°C;
the
strain
sporulated
poorly,
sporangiospores
being
variable.
Synonymy.
Though
Rh.
arrhizus
(Fischer
in
Rabenhorst,
1892)
was
described
prior
to
Rh.
oryzae
(Went
and
Prinsen
Geerligs,
1895),
Scholer
(1970)
preferred
the
latter
name.
In
his
opinion,
Rh.
arrhizus
was
an
extreme
form
of
Rh.
oryzae,
showing
applanate
columellae
which
are
very
unusual
in
Rh.
oryzae.
Some
sup-
port
may
be
found
in
Hagem's
(1907/08)
description
of
his
Mucor
arrhizus,
which
was
stated
to
be
very
similar
to
Fischer's
isolate,
also
producing
applanate
columellae
on
MEA
at
16°C,
but
globose
to
elongate
columellae
on
bread
at
22°
C.
However,
Fischer's
description
is
not
conclusive,
illustrations
or
type
ma-
terial
are
lacking,
and
therefore
the
species
is
treated
as
doubtful.
Vuillemin
(1906)
differentiated
Rh.
japonicus
from
Rh.
oryzae
on
the
basis
of
the
absence
of
growth
in
Raulin-solution
at
37°
C.
On
potato
agar
at
39°
C
growth
occurred,
though
poorer
than
in
Rh.
oryzae.
Further
there
were
slight
differences
in
growth
rate,
sporulation
and
colony
appearance,
and
slightly
larger
sporangiospores:
in
Rh.
japonicus
mostly
9
pm
in
length,
in
Rh.
oryzae
about
6-8
pm.
Similar
features
were
used
by
Vuillemin
(1902)
to
differentiate
Rh.
tonkinensis
from
Rh.
oryzae
and
Rh.
japonicus,
mainly
by
less
development
at
higher
temperatures.
Sporangiospores
of
Rh.
tonkinensis
averaged
8
pm
in
length
and
the
size
of
the
sporangia
was
noted
as
75(-100)
pm
in
diam.
In
Rh.
japonicus
sporangial
diameters
were
stated
to
be
160-215
pm.
The
diagnosis
of
Rh.
oryzae
mentions
sporangia
up
to
175
pm,
"in
case
of
good
nourishment".
Now
that
the
wide
range
of
variability
of
Rh.
oryzae
is
better
known,
the
above
species
can
easily
be
reduced
to
synonymy.
According
to
Saito
(1904),
Rh.
tritici
differs
from
Rh.
oryzae
in
the
occurrence
of
swellings
in
the
sporangiophores
and
confluent
sporangiospores.
The
type
strain,
CBS
128.08,
was
studied
by
Hanzawa
(1915).
There
are
also
notes
avail-
able
from
the
CBS
files
which
prove
that
it
is
still
in
the
original
condition.
Hagem
(1907/08)
described
Mucor
norvegicus,
isolated
from
soil
in
Norway,
and
deposited
a
culture
at
the
CBS,
but
this
is
now
lost.
Lendner
(1908)
com-
pared
Rh.
nodosus
with
this
strain
and
found
them
to
be
identical.
This
was
later
confirmed
by
Hagem
(1910).
Lendner's
(1908)
drawings
of
infundibuliform
columellae
are
reminescent
of
the
"applanate"
columellae
described
by
Fischer
(in
Rabenhorst,
1892)
in
Rh.
arrhizus
and
by
Hagem
(1907/08)
in
the
synony-
mous
Mucor
arrhizus
grown
at
low
temperatures.
The
type
culture
of
Rh.
batatas
now
deviates
from
older
descriptions
in
pro-
ducing
sporangiospores
up
to
6-7
pm
in
length
(MEA,
25°
C):
Nakazawa
(1909)
noted
sporangiospores
4.4-12.3
x
3.5-5.2 pm,
and
Hanzawa
(1915)
4.2-9
x
(3—)4.2-7.2
pm.
SCHIPPER:
RHIZOPUS
15
The
morphological
and
physiological
characterization
of
Rh.
delemar
was
dated
March
1912,
but
as
soon
as
September
1912
a
paper
was
presented
by
Hanzawa
in
which
he
remarks
on
the
similarity
of
Rh.
delemar
and
Rh.
oryzae:
the
former
might
be
just
a
more
profusely
sporulating
strain
of
the
latter.
The
type
culture
of
Rh.
delemar
still
fits
the
original
diagnosis.
Ellis
(1981)
investiga-
ted
the
influence
of
temperature,
medium
and
age
on
the
size
of
sporangiospores
in
colonies
originating
from
a
single
sporangiospore
of
Rh.
delemar
(most
proba-
bly
the
type
strain).
He
showed
that
both
medium
and
temperature
have
a
great
effect
on
sporangiospore
size;
the
age
of
the
colony
much
less
so.
The
type
strain
of
Rh.
delemar
var.
minimus
differs
from
that
of
the
typical
variety,
CBS
120.12,
in
having
shorter
sporangiophores,
smaller
sporangia
and
columellae
and
the
occurrence
of
variable
sporangiospores,
some
large
and
partly
misshapen.
Rhizopus
kasanensis
was
mentioned
prior
to
its
diagnosis
by
Trubin
(1911)
as
a
pathogen
on
the
eyes
of
rabbits.
The
taxon
was
later
described
twice
by
Hazawa
(1912,
1915),
and
though
the
type
culture
is
lost,
these
publications
are
sufficiently
clear
to
decide
on
its
synonymy
with
Rh.
oryzae.
Hanzawa
(1915)
distinguished
Rh.
usamii
from
the
related
Rh.tritici,
Rh.
ton-
kinensis
and
Rh.
batatas
on
the
basis
of
colony
colour,
slight
differences
in
spor-
angiospore
size
and
minimum
temperature
for
sporulation,
Rh.
usamii
sporulat-
ing
at
lower
temperatures
(8-10°C).
The
probable
type
strain,
CBS
406.51
was
indistinguishable
from
Rh.
oryzae.
CBS
257.28,
sent-by
the
CLMR
(Central
Laboratory,
South
Manchuria
Rail-
way
Co.,
Dairen)
is
probably
authentic
for
Rh.
formosaensis.
Morphologically
it
is
just
another
"medium-
Rhizopus";
no
distinguishing
features
are
present.
Bruderlein
(1917),
who
never
before
had
come
across
poorly
sporulating
Mu-
cor
and
Rhizopus
strains,
regarded
the
scarcity
of
sporangiophores
and
sporan-
gia
in
his
Rh.
maydis
as
a
major
difference
with
known
species.
The
type
culture,
CBS
110.17
developed
better
on
CMA
at
30°C
than
on
M
EA
at
25°
C,
producing
sporangia
up
to
150
pm
in
length
and
ellipsoidal
columellae.
The
latter
were
illustrated
in
Bruderlein's
(1917)
paper
as
subglobose.
CBS
401.51
was
sent
to
the
CBS
by
K.
Kominami
(Nagao
Institute,
Tokyo)
as
Rh.
chungkuoensis
with
a
reference
to
the
diagnosis,
but
without
a
clear
state-
ment
that
indeed
the
type
strain
was
concerned.
It
had
slightly
shorter
sporangio-
phores
(800-1000
pm),
but
in
its
remaining
characters
the
strain
is
indistinguish-
able
from
Rh.
oryzae.
CBS
258.28,
the
type
strain
of
Rh.
hangchao
was
sterile
when
this
study
was
started.
The
type
culture
of
Rh.
liquefaciens,
CBS
260.28
sporulated
rather
poor-
ly
on
MEA,
but
much
better
on
CMA.
On
the
latter
medium
the
sporangia
were
up
to
175
pm
and
the
sporangiospores
5-8(-10)
pm.
The
type
strain
of
Rh.
pseudochinensis,
CBS
264.28
produced
(MEA,
25°C)
sporangiophores
measuring
1000(-1500)
x
13(-15)
pm,
sporangia
175
pm
in
diam,
with
subglobose
to
ellipsoidal
columellae,
up
to
90
pm
in
height,
and
sporangiospores
up
to
8
pm
in
length.
That
of
Rh.
shanghaiensis,
CBS
404.51
has
not
changed
since
its
receipt
a
t
th
e
CBS
i
n
1951
,
an
d
p
ro
duces
sporangio-
phores
up
to
800(-950)
pm
and
sporangiospores
up
to
8
pm
in
length.
CBS
393.34,
the
type
strain
of
Rh.
p
e
k
a
d
ev
i
ates
f
rom
th
e
di
ag
nosis
in
produc-
ing
slightly
longer
sporangiophores
and
slightly
larger
sporangia.
16
STUD.MYCOL.
25.
1984
it
A
study
of
CBS
405.51,
type
strain
of
Rh.
thermosus,
as
well
as
careful
analysis
of
the
original
description,
showed
that
just
another
Rh.
oryzae
was
concerned.
Also
CBS
330.53,
the
type
strain
of
Rh.
boreas
represents
the
same
species,
though
with
rather
short
sporangiophores,
up
to
800
pm,
and
small
sporangia,
up
to
125(-150)
pm.
According
to
Dawson
and
Povah
(1928)
Rh.
fusiformis
is
characterized
by
cottony
mycelium,
sparse
production
of
sporangia
and
branched
sporangio-
phores
with
a
fusiform
swelling
at
the
point
of
attachment
of
lateral
branches.
On
MEA
at
25°C
the
type
strain,
CBS
266.30,
produces
sporangia
up
to
175
pm
in
length
instead
of
up
to
113
pm
as
stated
in
the
diagnosis.
Judging
from
protologue
(Nielsen,
1929),
Rh.
suinus
is
a
micro-Rhizopus.
However,
CBS
295.31,
the
probable
type
strain,
is
closer
to
Rh.
oryzae.
Scholer
and
Muller
(1971)
too
considered
the
species
to
belong
in
micro-Rhizopus,
and
CBS
295.31
an
atypical
strain
of
Rh.
oryzae.
CBS
385.34,
type
culture
of
Rh.
achlamydosporus
differs
slightly
from
the
ma-
jority
of
Rh.
oryzae
strains
by
producing
shorter
sporangiophores,
some
of
which
with
inconspicuous
swellings,
and
rather
large
sporangiospores.
The
type
strain
of
Rh.
bahrnensis,
CBS
386.34,
produces
on
MEA
at
25°C
sporangiospores
up
to
10(-12)
pm
in
length,
which
is
shorter
than
is
usual
in
the
group.
On
CMA
at
30°C
a
lower
incidence
of
narrow
spores
is
found.
The
diagnosis
of
Rh.
chiuniang
(Yamazaki,
1919)
was
not
available
to
the
present
author.
The
paper
also
included
a
variety
isofermentarius,
but
it
could
not
be
ascertained
whether
this
was
classified
in
Rh.
chiuniang.
The
type
strain,
CBS
389.34,
is
of
the
common
medium-Rhizopus
type.
The
authentic
material
of
Rh.
chiuniang
is
probably
lost.
Takeda
(1935)
described
Rhizopus
chungkuoen-
sis
var.
isofermentarius
nov.
var.,
with
the
following
key-features:
sporangia
(39.9—)80-110(-199.5)
pm,
sporangiophores
(186.2—)400-800(-1396.5)
x
(8.8—)9-10(-12.1)
pm,
columellae
(35—)45-55(-70)
pm,
sporangiospores
(5.5—)7-8(-11.5)
x
(3.8—)5-6(-6.6)
pm;
growth
was
observed
at
40°C
but
not
at
45°
C.
CBS
391.34,
type
culture
of
Rh.
javanicus,
is
identical
to
Rh.
oryzae,
except
for
the
very
variable
sporangiospores,
which
are
up
to
8(-16)
pm
in
length.
Takeda
and
Takamatsu
(1949)
described
Rh.
javanicus
var.
kawasakiensis
as
differing
from
the
typical
variety
in
growing
with
inulin,
ammonium
nitrate
and
glycocoll,
and
in
its
saccharification
ability.
In
the
type
strain,
CBS
402.51
few
rhizoids
were
produced,
which
made
it
rather
difficult
to
determine
sporangio-
phore
length.
In
the
1951
CBS
files
the
sporangiophores
were
stated
to
measure
855-1425
pm
in
length;
in
1982
they
were
up
to
750
pm
in
length.
CBS
395.34,
most
probably
the
type
strain
of
Rh.
semarangensis,
was
almost
sterile,
but
some
sporulation
could
be
induced
on
CMA
at
30°C.
Sporangio-
phores
were
very
short
(up
to
250
pm)
and
sporangia
small
(up
to
80
pm);
co-
lumellae
were
semi-globose,
sporangiospores
variable,
up
to
10
pm
in
length,
and
chlamydospores
abundant.
The
diagnosis
of
Rh.
sontii
could
not
be
traced.
Reddi
and
Subrahmanyan
(1935)
stated
that
this
rice-fermenting
fungus
had
been
provisionally
described
in
their
first
publication.
It
would
be
allied
to
Rh.
cambocljae,
but
differed
in
more
pronounced
physiological
activities.
The
type
culture,
CBS
279.38
is
a
SCHIPPER:
RHIZOPUS
17
Rh.
oryzae
with
variable
sporangiospores,
up
to
8(-14)
gm
in
length.
The
Rh.
cambodjae
material
is
probably
lost,
and
the
concise
protologue
does
not
allow
proper
identification.
Acknowledgements
The
author
is
indebted
to
Drs
K.
Furuya,
K.
Hara
and
T.
Yokoyama
for
making
accessible
several
first
descriptions
of
older
Japanese
Rhizopus
species.
Dr.
H.
Scholer's
permission
to
use
his
taxonomic
information
on
the
genus
is
gratefully
acknowledged.
Thanks
are
due
to
Miss
L.
van
Dijk,
I.
ten
Hoedt,
Mrs
A.
Spaapen
and
T.
van
den
Berg
for
assistance.
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SCHIPPER:
RHIZOPUS
19