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1975 A Photomicrographic Guide to the Saprolegniaceae of Illinois Ronald L. Butler Eastern Illinois University This research is a product of the graduate program in Botany at Eastern Illinois University. Find out more about the program.
Recommended Citation Butler, Ronald L., "A Photomicrographic Guide to the Saprolegniaceae of Illinois" (1975). Masters Theses. 3482. https://thekeep.eiu.edu/theses/3482
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pdm A PHOTOMICROGRAPHIC GUIDE TO THE -
SAPROLEGNIACEAE OF ILLINOIS (TITLE)
BY
RONALD L. BUTLER - --
B. S., Eastern Illinois University, 1973
THESIS
SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
MASTER OpSCIENCE IN THE GRADUATE SCHOOL, EASTERN IUINOIS UNIVERSITY
CHARLESTON, ILLINOIS
1975 YEAR
I HEREBY RECOMMEND THIS THESIS BE ACCEPTED FULFILLING AS THIS PART OF THE GRADUATE DEGREE CITED ABOVE
''-L� ifa oAr L'llS- ADVISER
:-,�I�l�JS- oAr A PHOTOMICROGRAPHIC GUIDE TO THE
SAPROLEGNIACEAE OF ILLINOIS
BY
RONALD L. BUTLER
B. S., Eastern Illinois University, 1973
ABSTRACT OF A THESIS
Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Graduate School of Eastern Illinois University
CHARLESTON, ILLINOIS 1975 ABSTRACT
There is a paucity of information concerning the occurrence and distribution of the Saprolegniaceae of Illino is. These fungi , commonly called "water molds", are of particular· interest as many
are potential parasites of fish, crustaceans, and other aquatic
plant and animal life . It is of considerable interest to students of the fungi and of practical value to the fisheries biologists and environmentalists to have available a me�ns of identification
for these organisms .
This paper provides a descriptive and photomicrographic
account of the Saprolegniaceae of Illinois. Included herein
are dichotomous keys to the genera of this family as well as
generic descriptions for each of the 12 genera known to occur
in Illinois. For each genus containing more than a single species ,
a dichotomous key is provided for the identification of species .
A total of 68 species is reported herein. Each of 50 species is
illustrated with four or more separate figures, these designed
to emphasize the diagnostic characteristics for each species.
Each species is further defined by brief notes concerning the
distinguishing species characteristics . The species reported
herein include twenty new Illinois state records and one ,
Achlya radiosa Maurizio, a new North American record. ACIZNOWLEDGI 1EI J'I'S
The writer wishes to express his thanks to �he Department of Botany, Eastern Illinois University, for financial assistance in the form of assistantships for his two years of residence.
He is sincerely grateful to Professor William W. Scott for his advice, encouragement , and critical review of the manuscript. He extends special thanks to Dr . Wesley Whiteside and Dr. Richard Smith, members of his graduate committee for their helpful suggestions and reading of the manuscript.
Sincere thanks goes to his wife , Mary K. Butler, for her aid and encouragement.
The writer would like to thank Dr . Roland L. Seymour ,
The Ohio State University, and Dr . M. w. Dick , University of
Reading for providing a number of cultures for use in this
investigation.
i Tl\BLE OF CONTEt-!TS
INTRODUCTION • • • • ...... 1
TAXONOMIC CRITERIA ...... 2
1'1ATERIALS AND METHODS • ...... • • • • • 6
PREVIOUS REPORTS OF THE SAPROLEGNIACEAE OF ILLINOIS • . . 8
SYSTEMATIC SECTION • • ...... 9
Key to the Genera of Saprolegniaceae • • • • • • • --- 9
!:_yth ioo.si�_ de Bary ...... 1 2
*Pythiops is cvm�s� de Bary • • • • • • • • • • • • 12
Saprol�nia c. G. Nees • • • • • • • • • • • • • • • 13
Key to the Species of Saoroleqni� • ...... • 14
. . . .••• 17
_;3aproleonia subterranea (Dissmann) Seymour . • • 17
_?aprol_�qnia anisospora de Bary . . . 18
. . . *Saprol.�qnia ------eccentric a (Coker ) Seymour • • 19
*Saproleqnia hypoqvn� (Pringsheim) de Bary ••••19
Sapro_leonia turfosa (Minden) Gaumann • • • • • • 20
Saproleg0 ia torulosa de Bary • • • • • • • • • • 20
Saproleqnia ferax (Gruith.) Thuret • • . . . . . 21
22
Saproleo_ni� diclina_ Humphrey • • • • • • • • • • 23
Saproleqnia litoralis Coker •••••••••••23
Saoroleania alomerata (Tiesenhausen) Lund • • • • 24
•saproleqnia unispora (Coker & Couch ) Seymour . . 24
Saprolegn ia megasperma Coker • • • • • • • • • • 25
Leptoleqn ia de Bary • • • • • • • • • • • • • • • • • 25
Key to the Species of Leptolegn ia • • • • • • • • • 26
ii Leptolegnia caudatn de Bary • • • • • • • • • • • 26
Le2toleqn:_�a subterranea Coker und Harvey • • • • • 2 7
Aphanomyces de Bary • • ...... 27
Key to the Species of Aphanomyces • • • • • • • 28
Aphanomvces laevis de Bary • • • • • • • • • • • • 29
Aphanomyces helicoides von �inden • • • • • • • • 29
Aphanomyce� scaber de Bary • • • • • • • • • • • • 30
Aehanomyces stellatus de Bary •••••••••••31
Aphanomvces parasiticu� Coker • • • • • • • • • • 31
Achlya C. G. Nees • • • • • • • • • • • • • • • • 32
Key to the Species of Achlya • • • • • • • • • • • • 33
Achlya bisexualis Coker and A. Couch •••••••37
Achlya ambisexualis J. R. Raper • • • • • • • • • 37
• Achlya_ caroltniana Coker • • • • • • • • • • • • • 38
Achlva racernosa Hildebrand • ...... • 38
•AcE)� apiculata de Bary •••...... • • 39
• �-chl ya polyandra Hildebrand • • • • • • • • • • • 39
Achl� orion Coker and Couch • • • • • • • • • • • 40
Achlya debarvana Humphrey • • • • • • • • • • • • 40
Achlya americana Humphrey . . . . • • • • . . . . 41
Achlya consoicua Coker • ...... • • • 42
*Achlya oblonoata de Bary • • . • • • • • • • • • • 42
*Achlva dubia Coker ••••...... • • • • • • 42
Achlya intricata Beneke • • • • • • • • • • • • • 43
Achl� prolif eroides Coker • • • • • • • • • • • • 44
• • • • • • • • • *Achlva--- diffusa (Harvey) Johnson 44
Achlya flagellata Coker • • • • • • • • • • • • • 45
iii ...... 46
Achly_� P_E_s>lifer� C. G. Nees •••. . . . . • • • 46
...... • • • 4 7
...... • • • 48
. . . • • • • 48
*Achl\�.� P2l?J._l_�os� Humphrey • • • • • • • • • • • • 50
dio_sa_ l"'iaurizio • • • ...... 52 • :,\_£l}_l_y� E'�.
• 52
...... • 53
...... • 53
. . . • • 54
Protoach�_ya Coker • • • ...... 54
Key to the Species of Proto�chly_9-. • . . . . . 55
Protoach� Earadq�a (Coker) Coker •••••••• 55
!:'.E.
�la_l]_es de Bary • • • • • • • • • • • • • • • • • • • 56
Aplan�-� ai_:_drogvnus_ (Archer ) Humphrey . . . • 57
...... • • �·Thraustotheca���.-� Humphrev- . 58
Key to the Species of Thraustot�eca • • • • • • • • 58
Thr�ust�th�_as:: clavata (de Bary) Humphrey • • • • • 58
�a_Jy_F-tr_?_!�.2!1i� Coker • • • • • • • • • • • • • • • • • 59
Calvptralegn�� ach!Yoides (Coker & Couch ) Coker • 60
Dictyuchu� Leitgeb • ...... • • . . • • • • 60
Key to the Species of Dictyuchus • • • • • • • • • • 61
Dictyuchus monosporus Leitgeb • • • • • • • • • • 62
iv Dictyuchus misso�riensis Couch • • • • • • • • • • 63
...... • • 63
Dic�uchus a�01-Y.2_ides Coker and Alexander • • • • • 64
Dictyuchus pseudoachlyoic!._es Beneke • • • • • . . . 64
Dictvuchus pse�dod?:._ctX,?._� Coker and Braxton • . . . 64
Brevileania Coker and Couch • • • • • • • • • • • • • • 65
Key to the Speci es of �rey�leo�ia • • • • • • • • 66
*Drevilegnia bispora Couch • • •••••••••••67
Brevilegnj..a diclina Harvey • • • • • • • • • • • • 67
Brevileonia �nisperrna Coker and Braxton • • • • • • 67
Br�_Y-�-�-�12�� me��rm� Harvey • • • • • • • • • • • 68
Brevi�egni� �ubclav?t� Couch • • • • • • • • • • • 68
Geoleonia Coker • • • • • • • • • • • • • • • • • • • • 69
Geoleania inf lat� Coker and Harvey • • • • • • • • 69
ILLUSTRATIONS • • • • • • • • • • • • • • • • • • • • . . . . 70
LITERATURE CITED • • • • • • • ...... 122
v LIST OF FIGURES
Figures
1-8 Pyth�ops is cvmos a de Bary • • • • • • • • • • • • • 70
9-12 Saproleonia 9steropho_ra de nary . . . . . • 72
13-16 S�_p-�_olenni� �ubt�rranea. ( Dissmann) Seymour • • • • 72
17-20 �?.2ro.egnia] . �cs:_en�_ri_<:.9_ ( Col�er) Seymour • • • • • • 74
21-24 ?ap_Egle�n�� b_yp_<�_gy�a (Pringsheim) de Bary •••••74
25-28 Saprol_�gniC?. tur:fosa _ (Minden) Gaumann • • • • • • • 76
29-32 Saoroleg_E':_ia torulosa_ de Bary ...... 76
33-36 ...... 78
37-40 §�ro�egni� 2�r. asitic� Coker . . • • 78
41-44 Saprole� diclina Humphrey • • ...... 80 ..
45-48 Saorole� litoralis Coker ••••••••••••80
49-52 Saprolegni� �nispora (Coker & Couch) Seymour . . . 82
53-56 Sa_pEol�gni� megasoerma Coker • • • • • • • • • • • 82
57-60 Lept�leo�i� caudata de Bary • • • • • • • • • • • • 84
61-64 Apl)anomyces _ laevis de Bary • • • • • • • • • • • • 84
65-68 AEhanomyces helicoides von Ninden • • • • • • • • • 86
69-72 Aphanomvces stellatus de Bary • • • • • • • • • • • 86
73-76 Ach� caroliniana Coker • • • • • • • • • • • • • 88
77-80 Achlya racemosa Eildebrand • ...... 88
81-84 Achlya apicu��ta de Bary • • • • • • • • • • • • • 90
85-88 Achlya EOly?ndra Eildebrand • • • • • • • • • • • • 90
89-92 Achly_�- o��on_ Coker and Couch • • • • • • • • • • • 92
93-96 ��hl_y� americ�na Humphrey • • • • • • • • • • • • • 92
97-100 �_s:hlva _s:2nsp_icua Coker • • • • • • • • • • • • • • 94 101-104 ...... • 94
105-108 • • • 96
·109-112 . . . . . 96
113-116 Achlva flaoellata Coker ...... 98
117-120 ...... • 98
121-124 . . . 100
125-128 ...... • • • 100
1?.9-132 f\�l�J:.::.'..?. £_
. . • . 133-136 ------1\c!;l va ---·treleaseana - ·-·------(Humphrey) Kauffman 102
. . . . • . . . 137-140 ----Achlva --recurva.. ----·--- Cornu • • • • • 104
141-144 . . . • • . . • . . . . . !\Ci�lY._� crenul.:ita·-·- Ziegler 104
145-152 !:rotoas..b.LY5.1_ b.Y.E.99..Y!la_ Shanor and Conover • • • • • • 106
153-156 �lanes androavnus (Archer ) Humphrey •••. . . . 108
157-160 Thraustotheca clavata (de Bary) Humphrey • . . . . 108
161-164 Thraustotheca orimo�chlya Coker and Couch • • • • • 110
165-168 CalY£traleonia achl_yoide�_ (Coker & Couch ) Coker • • 110
169-172 Dictyuchus mongs29ru� Leitgeb • • • • • • • . . • • 112
173-176 Dic_��chys anomalus Nagai •••••••••••••112
177-180 Dictyuchus missour.�ensis Couch • • • • • • • • • • 114
181-184 Dictyuchus pseud�achlyoides Beneke • • • • • • • • 114
185-188 Dictyuch�� Eseudodict.x2n Coker and Braxton • • • • 116
189-192 _?revileqnia b�a Couch • • • • • • • • • • • • • 116
193-196 .£3Fevilegnia diclina Harvey • • • • • • • • • • • • 118
197-200 Brevileania unisperm� Coker and Braxton • • • • • • 118
201-204 Brevileania subclavata Couch • • • • • • • • • . . 120
205-208 Geolcgnia inflata Coker and Harvey • • • • • • 120
vii INTRODUCTION
The student of aquatic biology seeking information on
the fungi inhabiting the freshv1ater environment must locate references in a wide range of scientific journals or in
obscure theses or in odd chapters of more general works . In
an attempt to alleviate this problem some authors (Johnson,
1956; Scott, 1961; Seymour , 1970) have published monographic
treatments of selected genera of aquatic fungi. Further studies
of this nature are needed. It is of considerable interest to
the student of the fungi and of practical value to the fisheries
biologist and environmentalist to have available a means of
identification of these organisms . The present paper provides
a descriptive and photomicrographic account of the diagnostic
characteristics of the members of the Saprolegniaceae of
Il linois . These fungi are of particular interest as many are
potential parasites of fish , crustaceans , and other aquatic
plant and animal life . The aquatic fungi may also serve as
pollution indicators since their growth is inhibited in waters
heavily contaminated with organic wastes from sewage treatment
plants and other industrial sources (Stevens, 19 74).
The Saprolegniaceae , with some 150 species, is the largest
family in the order Saprolegniales and is distinguished by the
formation of bif lagellate zoospores and the delimitation of the
zoospores within a zoosporangium. The two flagella , one of the
whiplash type and one of the tinsel type , are attached either
anteriorly or laterally. The primary zoospores are pyriform
with apically attached flDgella, while the secondary zoospores 2
are reniform with laterally attached flagella. l\11 members of the Saprolegniaceae are oogamous ; sexual reproduction involves
the fusion of a male gametangium (antheridium) with a female
gametangium (oogonium), the latter containing one to several
eggs (Fig. 79). The antheridium is differentiated into a
slender hyphal branch that is separated by a septum from a
clavate or tubular antheridial cell (Fig. 35). Whether the
antheridia appear at the same time or shortly after the
appearance of the oogonial initials, they elongate and make
contact with the oogonial wall. The fertilization of the
oosphere is accomplished when the contents of the antheridial
cell enter the oogonium through a fertilization tube (Fig. 100).
Motile gametes are absent among the Saprolegniaceae.
TAXONOMIC CRITERIA
The vegetative features of mycelial and zoosporangial
development are used to distinguish and separate the various
genera of the Sapro legniaceae. The variations in zoospore
discharge found in the genera of this family are as follows :
Saproleanoid: The primary zoospores emerge one by one through
one, or rarely more, exit pores and actively swim away from the
zoosporangium (Figs . 53-54).
Leptolegnoid: The primary zoospores are formed in a single row
within the zoosporangium; zoospore discharge is saprolegnoid
(Fig. 57).
Achlvoid: The primary zoospores encyst as they emerge from the
exit pore to form a loose, spherical cluster (Figs . 62, 101). 3
�anoid: The prim�ry zoospores encyst within the zoosporangium and germinate by germ tubes through t11e zoosporangial wall
(Fig. 153 ).
Dictvoid: The primary zoospores encyst within the zoosporangium; this encystment is followed by the germination of secondary zoospores through the exit papillae in the zoosporangial wall
(Figs. 169 � 170).
Thraustothecoid: The primary zoospores encyst within the zoosporangium and are liberated by the dissolution of the
zoosporangial wall (Fig. 15 7).
Secondary zoosporangial formation is quite common in the
Saprolegniaceae and may entail one or more of the following types:
Internal .._pr oliferation:---- The secondary zoosporanoium� is formed
inside a previously discharged zoosporangium (Figs. 37, 14 7).
Sympodial branching: The hyphae below the basal septum of a
delimited zoosporangium branches laterally (Fig. 146 ).
Cymose branchinq: A cluster of zoosporangia are formed due to
the repeated branching of the hyphal tip (Fig. 141 ). . Basipetal�� succession: Below the primary zoosporangium,
secondary zoosporangia are formed in basipetalous succession ,
and the zoospore discharge is through lateral exit pores
(Fig. 14 1).
Though they are not dependable taxonomic characters , many
aquatic fungi form aemmae (chlamydospores ), modified thick-
walled segments of the hyphae in which there occurs a dense
accumulation of protoplasm (Figs. 2, 29, 112 ). Whether
produced normally or in response to unfavorable cultural 4
conditions , these resistant bodies may germinate directly into a new mycelium or may function as zoosporangia (Figs . 29, 112) or , less frequently, as oogonia (Fig. 2).
While the vegetative and asexual characteristics are useful in delimiting the various genera of water molds , these features are not dependable for species separation. The separation and identific ation of species of aquatic fungi depend upon a combination of characters associated with the male and female reproductive organs . These include the oogonial shape and position , length and appearance of the oogonial stalk, oogonial wa ll ornamentation and pitting , size of oogonia and oospores , number and type of oospore , and the antheridial branch origin.
The oogonium may be borne laterally on an oogonial stalk of variable length, in an intercalary manner or terminally on the vegetative hyphae. The oogonial stalk may be straight , curved, bent or co iled. The ornamentation of the oogonium is an important characteristic in the genera of water mo lds .
The oogonial walls may be smooth-walled (Fig. 78 ), papillate
(Fig. 9), tuberculate (Fig. 149), crenulate (Fig. 196 ), mammiform (Fig. 129), or truncate (Figs . 138, 140 ). In many species of water mo lds , the oogonial wall has circular unthickened areas or pits that are either conspicuous or just discernible under high magnification (Figs . 45 , 95 ). These characteristics are quite variable; and pitted, sparsely pitted and unpitted oogonia may occur in the same species . Due to the variable nature of the size and shape of the oogonia and oospores, this is not a reliable character in species determination. While the number of oospores per oogonium is variable for: a given species, the oospore type generally remains constant .
The type of mature oospore formed is of primary importance
in species identification. A centric oospore is one which at maturity contains one or two peripheral layers of small oil droplets completely surrounding the central ooplasm (Fig. 32) .
A subccntric oospore is one which at maturity contains a
single layer of small oil droplets on one side of the ooplasm and two or more on the opposite side (Figs . 52, 56), or with
the single layer of small oil droplets not formed (Fig. 168) .
An eccentric oospore is one which at maturity contains a single
large oil globule located on one side of the oospore and not
entirely enclosed by the ooplasm (Fig. 104) . A subeccentric
oospore is one which at maturity contains one or more layers
of oil droplets on one side of the oospore (Figs . 7, 8). An
expersate oospore is very similar to an eccentric oospore in
that a large oil globule is formed; however, this oospore
type lacks an ooplasm (Figs. 63, 67). The large oil globule
is completely surrounded by a homogeneous protoplasm (Howard,
19 71) .
Relatively few species of the Saprolegniaceae possess a
constant antheridial type. In the majority of cases various
combinations occur in a single species . The terminology used
to describe antheridial branch origin is as follows:
Androqynous : The antheridial branch arises from the oogonial
stalk, but the antheridial cell is not a part of the oogonial
stalk (Fig . 121) . 6
Diclinous : The antheridial branch and the oogonium originate
on different hyphae (Fig. 103).
Exigvnous: The antheridial branch originates from the oogonial
cell above the ba3al septum (Fig. 124).
,!iypoqvnous : The antheridial branch is lacking, but the
antheridi�l cell is abstricted as a part of the oogonial stalk
just below the oogonium (Fig. 22).
Monoclinous: The antheridial branch and the oogonium originate
on the same hypha (Fig. 35) .
MATERIALS AND t.-JETHODS
The common methods of collection and isolation for the
aquatic fungi , as utilized in this investigation, have been
described in detail by Sparrow (1960), Scott (1961), Seymour
(1970) and Stevens (1974). Briefly, these procedures involve
the addition of split halves of hempseed, snakeskin, cellophane ,
or other suitable substrates to soil and water samples. These
"b aits" may be added to soil and water samples in the laboratory
or placed in suitable traps and submerged in aquatic sites in
the field. Unifungal cultures of the aquatic fungi are
maintained on sterilized hempseed halves.
There are a few problems associated with taking photo
micrographs of the Saprolegniaceae and other organisms that are
not stained or cannot by readily stained without adverse effects
to them ; the principal problem is the lack of contrast due to
the achlorophyllous nature of the fungal mycelium. However ,
a photomicrograph with good contrast can be made by using an 7
appropria te filter, phase-contrast, and/or varying the paper used for printing the negative.
The water molds were grown on the endosperm of hempseeds .
This permitted the use of small portions of mycelium under a glass coverslip without serious ly mutilating the hyphal filaments. Because of the short depth of field, the mycelium and related structures were at times difficult to bring into focus. By using small portions of the rnycelium and by repositioning the mycelial filaments , the object could be brought into focus.
The photomicrographs were taken with a Nikon S-Ke II microscope with an AFM camera attachment. Eastman Kodak
Panatomic-X 35rr� film was used with an orange filter. In an effort to produce a photomicrograph similar to what a fisheries biologist might view under a microscope , phase contrast was not used in this study.
A number of the species included in this guide have not been previously reported from Illinois, but have been collected and isolated by W. W. Scott and his students duririg the past several years. These species are so indicated in the table of contents by an asterisk. The present paper is the first report of these species from Illinois . All isolates utilized for this photomicrographic guide are maintained in the aquatic fungus collection of W. w. Scott, Eastern Illinois University ,
Charleston, Illinois.
The key to the species of Saprolegnia has been taken with modification, from Seymour (1970). Keys to the species 8
of the other genera are based, again with modification, upon
those of Scott (1961), Johnson (1956), Coker and Matthews (1937)
and Sparrow (1960).
PREVIOUS REPORTS OF THE SAPROLEGNII\CEAE OF ILLINOIS
The first reference to any Illinois species of the
Saprolegniaceae was made by Jones and Drechsler (1925) when they described a root rot of peas caused by Aohanomy_s:es
eutc�iches Drec11s ler. Some years later, Shanor and Conover
(1942) reported and described Protoachly� hypogvna as a new
species. In an unpublished thesis , Bretsnyder (1943) recorded
the occurrence of members of the Saprolegniaceae from the area
around Crystal Lake , Urbana, Illinois. Shanor and Saslow (1944)
described an unidentified isolate of Aph anomyces parasitizing
fish in the University of Illinois Vivarium. Beneke (1948a )
completed the first monograph of the aquatic fungi of Illinois ,
which included over 50 species belonging to the Saprolegniaceae .
In an unpublished thesis , Overman (1970) reported on the ' occurrence of · 20 species representing 7 genera of the
Saprolegniaceae from sites below where the proposed Lincoln
Reservo ir was to be constructed on the Embarras River. 9
Key to the Genera of Soprolegniaceae of Illinois
1. Prinary zoospores liberated from the zoosporangium swim
actively a\·:ay without prior encystment (as in Pythio2si�
or Sanroleonia • • • • • • • • • • • • • • • • • • • • • • 2 ------�--
1. Primary zoospores liberated from the zoosporangium encyst
at th8 orifice (as in Achlya ); or primary zoospores
encysting within the zoosporansium prior to liberation
{as in Dictyuc�us) ••. . . . . • • • • • • ...... 4
2. Primary zoospores liberated from the zoosporangiurn
swim actively away without prior encystment, and
later settle down and germinate directly to form
hyphae; zoosporangia tending to be more spherical than
elongate (Fig. 1) • • • • • • • . . . Pythiopsis, p. 12
2. Primary zoospores liberated from the zoosporangium
swim actively away without prior encystment , later
encyst, the cysts germinating to give rise to
secondary zoospores; zoosporangia elongate (Figs . 101,
201) • • • • • • • • ...... • 3
3. Zoosporangia differentiated from and of greater diameter
than the subtending hyphae ; zoospores formed in more
than one row in the zoosporangium (Fig . 53) ••......
...... • • • • • • • • • • • • • Sao.reJ.eg nia, p. 13
3. Zoosporangin undifferentiated from and of the same
diameter as the subtending hyphae; zoospores formed in
a single row in the zoosporangium (Fig. 57) •••• . . . .
...... • Leptolegn ia, p. 25 10
4. Primary zoospores liberated from the zoosporangium
encyst at the orifice, (Figs . 62 , 101) later
germinating to give rise to secondary zoospores . . . • 5
4. Primary zoospores encysting within the zoosporangium
prior to liberation, later germinate directly by
germ tubes through the wall of the zoosporangium,
(Fig . 153) or by the formation of secondary zoospores
that escape through the wall of the zoosporangium,
(Fig. 170) or by the formation of secondary zoospores
that escape following the deliquescence of the
zoospora�gial wall (Fig. 157) •••• . . . • • • • 7
5. Zoosporangia undifferentiated from and of the same
diameter as the subtending hyphae; ·primary zoospores
formed in a single row in the zoosporangium (Fig. 61 ) •
......
5. Zoosporangia differentiated from and of greater diameter
than the subtending hyphae; primary zoospores formed
in more than one row in the zoosporangium • • ...... • 6
6. All of the primary zoospores encysting in ·a spherical
clump at t�e mouth of the zoosporangium (Fig. 101) •••
...... • • • • • • • • • • • • Achlya_, p. 32
6. Some of the primary zoospores encysting in an
irregular clump at the mouth of the zoosporangium ;
some of the primary zoo spores swimming actively away
later to encyst (Fig. 145 ) . • • • • • Protoachlya , • 54 P
7. Oogonium containing more than one egg (Fig. 160) • • • • • 8
7. Oogonium containinq a single egg (Fig. 172) . • • . • • • 10 11
8. Encysted primary zoosporcs germinating directly by
germ tubes which penetrate the zoosporangial wall
(Fig. 15 3) ...... ••Aplan es , p. 56
8. Encysted primary zoospores germinating by the
formation of motile secondary zoospore� • • • • • • • • 9
9. Encysted primary zoospores liberated by the deliquescence
of the entire zoosporangial wall (Fig. 157) ••••••• . .
...... Thraustotheca, p. 58
9. Encysted primary zoospores liberated by the ccliquescence
of only the apical portion of the zoosporangial wall
(Fig. 165 ) • • • • • • • • • • • • • • �ptraleqnia, p. 59
10. Nycelium consisting of well-developed, branched
hyphac; secondary zoospores emerging through the
zoosporangial wall leaving behind a network of
primary zoospore cyst walls (Fig. 170) ••••. . . . .
...... Dictyuchus , p. 60
10. Mycelium consisting of depauperate , sparingly
branched hyphae; primary zoospore cysts liberated
by the deliquescence of the zoosporangial wall
float free prior t9 the emergence of motile
secondary zoospores (Fig. 201 ) or motile secondary
zoospore stage entirely lacking (Fig. 206) • • • • • 11
11. Encysted primary zoospores formed in more than one row
in the zoosporangium (Fig. 201) ; cysts forming germ
tubes or motile zoospores ••••••••� revilegnia, p. 65
11. Encysted primary zoospores formed in a single row in
the zoosporangium (Fig. 206 ); cysts never giving rise to
secondary zoospores ...... • Geoleqnia, p. 69 12
Genus : _!.?_ythiopsis de Bary
Bot. Zeit., 46: 609. 1888.
The genus Pvthioosi� includes a small group of water molds that produce only zoospores of the primary type. These are formed in short , plump , spherical zoosporangia which usually have a distinct apical papilla. Secondary zoosporangia tend to form clusters on short lateral stalks from below the primary zoosporangia . Zoospore discharge in Py thiocsis is saprolegnoid; the primary zoospores swim actively, encyst, and germinate to produce a mycelium. This condition is said to be monoplanetic
(monomorphic ) in contrast to tr1e diplanetic (dimorphic ) condition found , for example , in species of Saproleania . Gemrnae are produced by isolates of Pythiopsis in abundance and often in chains . These resemble zo osporangia in appearance and may function as zoosporangia after a period of dorma ncy . Oogonia are produced in culture without difficulty by most isolates of
_Pythiops is . When immature, the oogonia resemble the zoosporangia and gemmae in shape and size, being typically spherical to pyriform. At maturity, the oogonia contain a single (rarely
2-3) eccentric oospores . The antheridia arc short and thick , typically androgynous (rarely diclinous ) and originate close to the oogonium.
Pythiopsis .sy_mo sa de Bary
Bot. Zeit ., 46: 631. 1888 .
(Figs . 1-8)
Isolates of P. cymosa from Il linois do not differ significantly from the formal description of the species as 13
defined by Coker and l\�atthews ( 193 7). Isolates of P • .£Y_mO$� may be distinguished from other species of �vthiops J� by the
zoosporangia , all of which are globose or clavate (Fig. 1) ,
and by the oogonia , which are generally spherical or pyriform,
unpitted, and often ornamented with a few blunt outgrowths
(Figs. 4, 6). In this species the single oospore has been
described as subeccentric (Dick , 1960) with a lunate cap of relatively large oil droplets on one side (Fig . 8) . 'l'he
antheridial branches are short, stout , and originate close
to the basal wall of the oogonium (Fig. 5).
Genus : Saproleqnia C. G. Nees
Nova Acta Acad. Leop.-Carol. , 11: 513. 1813 .
The genus Saprolegni�, consisting of more than fifty
reported species , is a relatively large and well-known group
of water molds. Isolates of Saprolegnia may be readily
distinguished from other genera of water molds by the size,
shape, and method of renewal of the zoosporangium; and by the
type of zoosporangial discharge exhibited. The usually clavate,
cylindrical, or filiform zoosporangia are generally terminal
and of greater diameter than the subtending hyphae and are
characteristically renewed by internal proliferation. In
addition to internal proliferation as a means of zoosporangial
renewal, renewal by cymose branching and/or basipetalous
succession is of relatively frequent occurrence. The frequency
of both methods of zoosporangial renewal vary with the species ,
and in all species these variations are enhanced by unfavorable 14
cultural conditions . Zoosporangieil renGwal by sympodial branching is not commonly encountered among species of
Saproleonia. Zoospore discharge in the genus is termed saprolegnoid and involves the rapid emergence of the primary zoospores one by one through a terminal exit pore . The primary zoospores swim actively away from the zoosporangium and , after a period of motility, encyst. Under unfavorable cultural conditions, most species may exhibit aplanoid or dictyoid zoospore discharge . Laterally biflagellate secondary zoospores emerge from the primary zoospore cysts following a relatively short period of rest. These swim actively, later encyst, and give rise to vegetative hyph ae .
The generic concepts of Saproleania have been expanded to include those species which formerly belonged to the genus
Iso_achlva (Seymour , 19 70). The genus Isoachlya was distinguished by the presence of cymose branching as in Ac}}_� and internal
proliferation as in �aproleqnia , as the mode of formation of
secondary zoosporangia, coupled with dimorphic zoospores
swimming as in Sapr�leonia. Since cymose branching is an
accepted characteristic in several species of Saprolegnia ,
there is no justification for the separation of these genera.
Those species formerly referred to the genus Isoachlva are
regarded herein as members of the genus Saproleania.
Key to the Illinois Species of Saoroleania
1. Oogonial walls ornamented • • • • • • • . . . . . • • • • 2
1. Oogonial walls smooth, never ornamented • • • • • • • • • 3 15
2. Oogonial walls densely papillate (Fig. 9) •••• . . .
••••••••.••••••••S. astcroohora, p. 17
2. Oogonial walls sparsely and irregularly papillate
(Fig. )5) ••••. . . • • . •.s. subterranea , p. 17
3. Oospores eccentric or subeccentric • • • 4
3. Oospores centric or subcentric • • . . . • • • . . . . . 5
4. Oospores mostly more than 3 per oogonium; antheridial
branches mostly diclinous; zo ospores variable in size
• • • • • • • • • • • • • • • • • �· anisospora, p. 18
4. Oospores mostly less than 3 per oogonium; antheridia
absent (Fig. 17 ); zoospores uniform in size •••
• • • • • • • • • • • • • • • • • S. eccentrica , p. 19 s. Oospores mostly more than 3 per oogonium • ...... 6 s. Oospores nostly less than 3 per oogonium • • • • • • • • 14
6. Antheridia strictly hypogynous (Fig. 22) • . . .
. . • ...... • . s. hypogyna, p. 19
6. Antheridia monoclinous and/or androgynous , and/or
diclinous , and/or completely lacking •••• 7
7. Oogonial wall conspicuously thickened and pitted (Fig. 26)
...... s. turfosa, p. 20
7. Oogonial wall relatively thin ; pitted or unpitted ••••8
8. Oogonia catenulate, usually becoming separated in older
cultures; oogonial wall mostly unpitted or with a few
conspicuous pits (Fig. 30) ••. . . S. torulosa, p. 20
8. Oogonia single; oogonial wall pitted or unpitted • • 9 16
9. Antheridia completely lacking or present in variable
nuirJ:>ers ; oogonial wall conspicuously pitted (Figs. 34 ,
35) • • • • • • • ...... s. ferax , p. 21
9. Antheridia usually present ; oogonial wall pitted or
unpitted • • • • • • • • • • • • • • • • • • • • . . 10
10. Oospores subcentric ; anthcridial branches mostly
diclinous ; oogonial wall unpitted (Figs. 39, 40) . . .
......
10. Oospores centric ; antheridial branches variable ;
oogonial wall pitted or unpitted • . . . . . • • 11
11. Antheridial branches mostly diclinous , rarely monoclinous
or androgynous (Fig. 41) • • • • • • • • s. diclin�, p. 23
11. Antheridial branches mostly monoclinous or androgynous
rarely diclinous • • ...... • 12
12 . Oogonial wa ll sparsely but conspicuously pitted ;
oospores relatively large (av. 30 pm in diam. )
(Fig. 45) • • • • • • • • • • • • S. litoralis , p. 23
12. Oogonial wall abundantly and conspicuously pitted ;
oospores relatively small (av. 22-26 �m· in diam. ) • 13
13. Antheridial branches contorted, irregular , or glomerate;
hyphal branches clustered and contorted • • • • • • • • • •
••.•••.•••••••••••••s. gl omerata, p. 24
13. Antheridial branches not contorted or irregular or
glomerate; hyphal branches not clustered or contorted
(Fig. 35) •••• • • • • • • • • • • • • • s. ferax, p. 21
14. Antheridia present • • • • • • • • • • • • • • • • 15
14 . Antheridia absent (Fig. 49 ) ••••�· unisoora , p. 24 17
15. Antheridial branches mostly monoclinous ; oogonial stalks
si�ple (Fig. 55) ••......
15. Antheridial branches mostly androgynous; oogonial stalks
frequently branched (Fig. 13) • • • • s. subterranea, p. 17
Saprolcq1:1ia asterophora de Bary
Jahrb . wiss. Bot., 2: 189 . 1860.
(Figs . 9-12 )
Saprolegnia asterochora is easily separated from all other species of the genus by the densely papillate nature of the oogonial wa ll (Fig. 9). A single collection of this species from Illinois was made previously by Beneke (1948a). The isolates of s. asteroeh ora from Illinois do not differ significantly from the formal description of the species as emended by Seymour (1970). Dick (1969) described a subeccentric isolate of s. asterophora which he used as the type species for a new genus of the Saprolegniaceae , the genus Scolioleania .
Until a more thorough investigation of these isolates is made, it seems appropriate to accept the emended diagnosis of the species (Seymour , 19 70) which includes forms with subcentric and subeccentric oospores. All isolates observed of S. asterophora during this study exhibited subcentric oospores .
Saoroleqnia subterranea (Dissmann) Seymour
Nova Hedwigia, 19: 59. 1970.
(Figs . 13-16 )
The emended description of the species S. subterranea according to Seymour (1970 ) includes those isolates formerly 18
described under the binomial Isoa5:hly� intermedia (Coker and
Harvey) Coker. Beneke (1948a) lists a single collection of
I. intermedia among his isolates from Illino is . The oogonia of that isolate were described as having wavy walls with low irregular �rotrusions , sometimes with one papilla. The great majority of oogonia formed by Illinois isolates were smooth walled (Fig. 16 ). In two of these isolates , however , it was not uncommon to find some oogonia with one or two rather conspicuous papillae, and with the oogonial wall not wavy or irregular. Such variations do not exclude these isolates from the broad diagnosis of s. subtcrranea. Isolates of s. subterranea can be recognized by oogonia with few centric or subcentric oospores (Fig. 16) , oogonial walls occasionally papillatcd (Fig. 15 ), and sparingly branched androgynous antheridial branches (Fig. 13 ).
Saprolegnia anisosoora de Bary
Bot. Zeit ., 46: 619. 1888.
As its specific name implies , Saoroleqnia ani�osoora is unique in the formation of zoospores of variable sizes.
Isolates of s. anisosoora may also be distinguished by the eccentric nature of the oospore , the predominantly diclinous antheridial branches , and the oogonial wall pitted only under the attached antheridial cell. Seymour (1970) has described a number of isolates of s. anisospo ra with subeccentric oospores . All isolates of s. anisosoora from Illinois exhibited eccentric oospores . This species has been reported 19
from Illinois by Overman (1970). Efforts to induce sexual structures were not successful during the course of this investigation ..
Saproleqnia eccentrica (Coker ) Seymour
Nova Hedwigia , 19: 53. 1970 .
(Figs . 17-20)
Saprolegn ia eccentrica may be distinguished from other species of Saproleqni� by the eccentric nature of the oospores , these occurring few in number per oogonium (Fig. 19 ), and by the complete absence of antheridia (Fig. 17). Occasionally oogonia may be found with distinct papillae (Fig. 20). Since this species demonstrates a frequent occurrence of proliferating oogonia (Fig. 18 ), these 11papillae1' may well be an early stage of proliferation (Fig. 20) . This is the first report of s. eccentrica from Illinois.
§apro leqnia hypogyna (Pringsheim) de Bary
Bot. Zeit. , 41: 56. 1883 .
(Figs . 21-24 )
This unique species of Saprolegnia is readily recognized by the hypogynous nature of the antheridial cells . (Fig . 22 ).
In all other respects , for example, the relatively long oogonial stalks (Fig. 2 1 ) , the conspicuously pitted oogonial walls (Fig. 23) , and the centric nature of the oospore (Fig.
24 ), this species bears a marked similarity to certain
isolates of s. ferax. Isolates of �· hypogy_na have not been reported previously from Illinois. The Illinois isolates 20
do not differ from the formal description provided by Seymour
(1970).
Saproleqnia turfosa (Minden) Gaumann
Bo taniska Notiser , 1918-19 : 154 . 1918.
(Figs. 25-28)
Isolates of S� turfosa are easily recognized by the large
thick-walled, conspicuously pitted oogonia borne on very short
stalks and by the very short antheridial branches of androgynous
origin (Fig. 26). SaDroleqnia turfo� has been reported
previously from Illinois by Beneke (1948a ) and by Overman (1970).
Saproleqnia torulosa de Bary ..
Abhandl . Senck. Naturforsch. Gesell. 12 : 255. 1881.
(Figs . 29-32 )
Beneke (1948a ) described two isolates from Illinois under
the binomial Isoachl va toruloides . f·�o re recently Seymour ( 1970 )
discussed the probable relationships of I. toruloides ,
Saprolegn ia torulosa, and �· monilifera . Since he had not
observed living raaterial of any of these "species", Seymour
relegated them to a category entitled "imperfectly known or
doubtful taxa11 and made no further disposition of them. Hm·1ard ,
et al. (1970), from observations of sixteen isolates obtained
in Iceland, presented evidence to justify the valid epithet
s. torulosa to embrace the previously separate taxa of
s. monilifera , s. rhaetica , s. variabili�, Isoachly_9- toruloides , I. monilifera , I. torulosa var. oaucisoora , I. fh aetica and
I. torulosa. Isolates of S. torulosa can be recognized by the 21
mostly spherical oogonia which occur in chains in young cultures
(Fig. 30) , variable pitting of the oogonial wa ll, centric oospores
(Fig. 32) , and , when present , diclinous antheridial branches.
Saproleqn ia ferax (Gruith .) Thuret
Ann. Sci. Nat . Bot ., Ser. III , 14 : 214. 185 0.
(Figs . 33-36)
Among species of Saproleqnia, isolates of S. ferax are generally the most abundant in their occurrence and the most widespread in their distribut ion. According to the recent interpretation of the species concept (Seymour , 1970) , �· ferax embraces a variety of morphological types , many of which were preciously described as distinct species . These isolates vary greatly with regard to the percent of oogonia with attached antheridia . As originally defined , isolates of s. ferax were said to have antheridia on fewer than 10% of the oogonia.
Those isolates with features otherwise similar to S. ferax but with antheridia on about 50% of the oogonia were previously assigned to the taxon s. mixta; and those isolates with antheridia on nearly all of the oogonia were previously assigned to the taxon s. monoica. Since the percentage of oogonia with attached antheridia is an unstable characteristic (apparently altered by environmental conditions and/or substrate) and since the variation in oospore number and type , oogonial wall pitting, size, shape and position of the oogonium among these isolates is relatively slight, Seymour (1970) has reduced s. mixta and s. monoica to synonymy under the binomial Sapr oleg�ia ferax. 22
Br.etsnyd�r (1943), Beneke (1948a) , and Overman (1970) have all reported the occurrence of this species from Illinois under one or more of the above names . The great majority of the Illinoi� isolates of s. ferax were those in which the oogonia lacked antheridia entirely. neneke (1948a) also reported the occurrence of s. laooonica ::rom Illinois , a species which has since been reduced to synonymy by Cejp (1959) . The distinguishing features of s. ferax are the abundant oogonia with variable pitting , centric or subcentric oospores , and antheridial branches variable
in number , usually monoclinous or androgynous .
Saprolegn ia parasitica Coker
Saprolegniaceae , p. 57. 1923 .
(Figs . 37-40)
As originally proposed by Coker (1923) , the binomial
Saproleonia pa rasitica included all non-fruiting isolates of
Saproleqpi a associated with diseased fish and fish eggs . It
has become common practice, particularly among fisheries
biologists, to include in this tuxon any asexual isolate of
Saproleqn ia which exhibited a parasitic habit . It has been
shown by Scott and O'Bier (1962) that such parasitic isolates
of Saprolegn ia may represent a complex of several taxa and that
the absence of sexual structure in certain isolates may be
explained as a result of heterothallism. Kanouse (1932) first
described the sexual stage of an isolate under the name
s. parasitica. Since that time , O'Bier (1960) , Seymour (1970) ,
and . others have reported sexual structures in s. pa rasitica. 23
It is suggested that all parasitic isolates of Saprol_EE_9.n ia which fail to produce sex organs be reported as Saproleani� sp.
Beneke (1948a ) has previously reported numerous isolates of
S. pa rasitica from Illinois , some of which formed, in culture , a few typical unpitted and smooth-walled oogonia with many subcentric oospores filling the oogonium (Fig. 40) and witl1 mostly simple and delicate antheridial branches of diclinous origin (Fig . 39 ).
��1proleonia diclin� Humphrey
Trans . Amer . Phil . Soc. (N.S. ), 17: 109 . 1893.
(Figs . 41-44 )
Isolates of S. diclin� may vary considerably with respect to oogonial shape , size , and pitting, and with respect to oospore number and size. The range of such variation is sufficiently great to encompass those isolates previously reported as Sapro legn ia delica . Seymour (1970) has relegated
S. delica to synonymy as S. diclina. Saprolegn ia_ diclina may be readily distinguished by centric oospores .CFigs . 43-44 ) and mostly diclinous anthcridial branching (Fig. 41). Bretsnyder
(1943) and Beneke (1948a ) have reported numerous collections of S. diclina from Illinois .
Sapro leqnia litoralis Coker
Saprolegniaceae , p. 54 . 1923.
(Figs . 45-48 )
Saoroleania litoralis is readily distinguished from other species of Saprole0nia by the relatively large centric oospores 24
which are few in number (Fig . 48), by the sparsely but conspicuously pitted oogonia that occur m6 stly in a terminal position (Fig. 45), and by the abundant , mostly androgynous
antheridial branches (Fig . 47). Beneke (1948a ) has reported the occurrence from Illinois of a single isolate of s. litoralis.
Saor9legn ia qlomerata (Tiesenhausen) Lund
Kgl . Danske Vidensk. Selsk. Skrift ., Naturv. Math. , Afd. IX , 6: 14 . 1934 .
Isolates of �· g)omerata may be distinguished by their
abundantly and conspicuously pitted oogonia with numerous , relatively small centric oospores, and more particularly by their numerous irregular and contorted antheridial branches.
Irregular and contorted clusters of lateral hyphal branches may also occur. Several isolates of s. gl omerata have been reported from Illinois by Beneke (1948a ) under the synonym
Saprolegnia monoica var . _g_l omer2ta . Since Beneke (1948a ), isolates of s. qlomerata have not been reported.
Saprolegn ia unispo ra (Coker and Couch ). Seymour
Nova Hedwigia , 19 : 57. 1970.
(Figs . 49-52 )
Saoroleania unisoora was originally described under the
binomial Isoachlva uniscora on the basis of the type of
zoosporangial renewal. Seymour (1970) has shown that in this
species zoosporangial renewal may be by cymose branching and
by internal proliferation, and he has accordingly included all
such species in the genus Sanroleqnia. /\mo ng those species of 25
Saproleania with centric or subcentric oospores (Figs . 51, 52)
S. t1nispora may be distinguished by the oogonia with but one or two oospores and by the complete absence of antheridia (Fig. 49 ).
Rarely oogonia are formed with one or two distinct papillae
(Fig. 50). This is the first report of the occurrence of
S. �n ispo r� from Illinois.
Saproleqn ia mega sperma Coker
Saprolegniaceae , p. 56. 1923.
(Figs . 53-56)
1"\mong species of §_C?pr oleqn ia with centric or subcentric oospores , Saprolegnia �asnerma is easily distinguished by the oogonia with but one or two oospores and by the simple, unbranched , monoclinous antheridial branches (Fig. 55 ). Aside from the presence of antheridia , this species is remarkably similar to s. unisoora. Beneke (1948a ) reported the single occurrence of S. mega sperma from Illino is.
Genus : Le.£!£l egnia de Bary
Bot. Zeit., 46: 609. 1880.
The genus Leptolegn ia bears the same relationship to
Saproleqnia as does the genus /\ph anomyc es to Achlva in the manner of primary zoospore discharge . The mycelium of
isolates of Leotoleqnia is composed of delicate and sparingly branched hyphae which bear long, cylindrical zoosporangia of the same diameter as the subtending hyphae. The primary
zoospores are formed in a single row (uniseriate ), in contrast 26
to the multiseriate condition observed in species of Saproleqnia.
Zoospore discharge in .!:'.ept ol�c:;.£li a is saprolegnoid, the primary zoosporcs are elongate upon emergence but soon assume a pyriform shape , sv1im actively, and later encyst and give rise to laterally biflagellate secondary zoospores , as in Saoroleonj_a .
Zoosporangial renewal may be by internal proliferation. Gemmae are entirely lacking in L� ptc?legnia. In contrast to the many spored oogonia typical of most species of Saproleania ,
Leptoleqnia forms oogonia with a single , eccentric oospore which completely or nearly fills the oogonium.
Key to the Illinois Species of Leotole9n ia
1. Oogonia relatively small; oogonial wa lls nearly smooth;
antheridial branches diclinous ••••••L. caudata, p. 26
1. Oogonia relatively lar9e ; oogonial wall with conspicuous
warts and projections ; antheridia absent ••••••••••
• • • • • • • • • • • • • • • • • • • L. subterranea, p. 27
Leptolegn ia caudata de Bary
Bot. Zeit ., 46: 631. 1888.
(Figs . 57-60)
Isolates of L. caudata are easily recognized by the nearly
smooth-walled, unpitted oogonia borne on short lateral branches.
These oogonia are conspicuously smaller than those observed in
L. subterranea , and frequent ly have one or more beak-like
projections , often at the site of an antheridial attachment.
Antheridial branches are of diclinous origin with one to several ?7
antheridia per oogonium. Beneke (1948a) has reported two collections of L. caudata from Illinois . t�o st isolates of
L. -----caudata encountered in the present study did not differ from the original description except in the case of one isolate which exhibited a distinct coiling of the antheridial branches about the hyphae and oogonial stalks. Since this characteristic is lost under culture conditions in the same manner as exhibited by some isolates of Achlva pr oliferoide� and Aphanomyc es �elicoides , it seems appropriate at this time to retain this isolate, based on the diclinous antheridial branches and the smooth-walled oogonia , as L. caudata.
Lcptoleqnia subterranea Coker and Harvey
J. Elisha Mitch . Sci. Soc. , 41: 158. 1925.
Leptolegn_i a subterranea may be distinguished from L. caudata by the conspicuously ornamented oogonia and by the absence of antheiidia. As originally described , L. subterranea Coker and
Harvey in Harvey (1925 ), the oogonia were conspicuously larger
than those of other species of Leptoleqn ia � The single isolate of L. subterranea reported from Illinois by Beneke (1948a ) formed oogonia that were much smaller than those described by
Harvey. Isolates of L. subterranea were not found from Illinois
during this study.
Genus : Aph anomyc es de Bary
Jahrb . wiss. Bot., �: 178 . 1860 .
The genus A2hanomvces , consisting of some 30 reported
species , bears the same relationship to Achlya as does 28
the genus Leotolegn ia to Saoroleqnia. An extensive mycelium is developed by isolates of Aphanomvces , which is composed of delicate and sparingly branched hyphae bearing long, cylindrical terminal zoosporangia of the same dia�eter as the subtending hyphae. In contrast to the multiseriate condition characteristic of Achlya , the primary zoospores are formed in a single row
(uniseriate) . Zoospore discharge in AEh anomyc es is achlyoid
and zoosporangial renewal occurs, but rarely, by sympodial branching , �nd never by internal proliferation! Secondary
zoospores emerge from the encysted primary zoospores ; these
swim actively, encyst , and later germinate to form hyphae .
Following the emergence of the secondary zoospores , a cluster
of "ghosts'' remains at the mouth of the zoosporangia, these
represent the persistent cell walls of the primary zoospore
cysts , a feature unique to �hanomyc es and Achlya . Gemmae
are generally lacking among isolates of �phanomyces . In
contrast to the many-spored oogonia typical of most species
of Achlya , isolates of Aph anomyc es form oogonia with a single
oospore (rarely 2) which does not completely fill the oogonium.
Key to the Illinois Species of �ph anomyc es
1. Oogonial walls smooth • • • • • ...... • • • • • 2
1. Oogonial walls irregular , undulate or ornamented • • • • 3
2. Antheridial branches not coiling •••A. laevis , p. 29
2. Antheridial branches coiling about the oogonial stalk
and subtending hyphae (Fig . 65) A. helicoides , p. 29 29
3. Oogonial wall with relatively short papillae or spines . . .
...... e • • A • • e • . . . A. �c aber , p. 30
3. Oogonial wall with relatively long papillae or spines • • 4
4. Oogonia up to 32 pm in diameter with blunt , conical
projections 6-7 pm in length ; usually saprophytic
(Fig. 69) • • • • • • • • • • • • • A. ste��atus , p. 31
4. Oogonia up to 22 pm in diameter with sharp-pointGd
spines 7-8 pm in length ; usua lly parasitic on Achlya
...... A. pa rasiticus , p. 31
Aph anomyc es laevis de Bary
Jahrb. wiss. Bot. ,�: 179 . 1860 .
(Figs . 61-64 )
Aphanornvce� lttevis is the most commonly co l lected species of the genus. As defined by Scott (1961), this taxon is restricted to those isolates with smooth-walled oogonia and antheridial branches that do not exhibit a tendency to coil or wrap themselves about the oogonial stalk and adj acent hyphae .
Beneke (1948a ) and Overman (1970) have reported numerous collections of A. laevis from Illinois.
Aphanomyc e� helicoides von �inden
Kryp-togarnenfl. Mark Brandenburg , 5: 559. 1915.
(Figs . 65-68)
Aphanomvces helicoides may be distinguished from A. laevis and from all other species of A�-ohanomvc....___es with smooth-walled oogonia by the conspicuous coiling of the antheridial branches. 30
In A. helicoides the antheridial branclies wrap about the oogonial
stalk and sometimes envelop the oogonium, and coil tightly about
the adjacent hyp11ae (Figs . 65 , 66 ). Hyphal conglomerates or vegetative knots of entwined hyphae are frequently produced by
isolates of A. helicoides . Deneke (194 8a) reported that , in
certain isolates of A. laevis from Illinois , the antheridial branches sometimes exhibited a tendency to coil . It is quite
possible that such isolates should be referred to A. helicoides .
Other reports emphasize the variability of antheridial branch
coiling and the fact that in certain isolates of A. hclicoides
this characteristic is lost upon subculturing (Howard et al,
1970 ). In the present study, all Illinois isolates exhibited
pronounced coiling of the antheridial branches and this
feature generally persisted upon subculturing.
Aph anomyc es s�abe� de Bary
Jahrb. wiss. Bot. ,�: 178. 1860.
Isolates of A. sca�er may be distinguished from other species
of Aphanomyc es by the tuberculate or spiny oogonia , and by the
single diclinous or rarely androgynous antheridia. Those isolates
with oogonial walls irregularly roughened were segregated by
Scott (1961) to Aphanomvces irrequlare. Several investigators
(Humphrey, 1893 ; Coker , 1923; Beneke , 1948a ; Howard et al, 1970)
have reported isolates identified as A. scaber with oogonial
walls varying from irregularly roughened to tuberculate to
spiny. Such variation did not occur in the same isolate among
members of this species complex reported herein. Howard et al. 31
(1970) suggest t11at the binomial A. irrequ lare be reduced to synonymy under £p_banornyces scaber. Beneke (1948a ) has reported numerous occurrences of A. scaber frorn Illinois. Efforts to induce sexual structures were not successful during the course of this investigation.
Aphanornyc e� stellatus de Bary
Jahrb . 1..viss. Bot ., 2: 178. 1860.
( Figs . 69-72)
Among those species of Aphanomvces with ornamented oogonia ,
A. stellatus is easily distinguished by its numerous bluntly conical tubercles that project 6-7 pm from the oogonial wa ll
(Figs . 71, 72). The antheridia , from one to several, tend to coil around the oogonia . The antheridial branch origin may be monoclinous , diclinous , or, rarely, androgynous ( Fig . 69 ).
Beneke ( 1948a ) has reported A. stellatus from Illinois.
Aphanomyc es oarasiticus Coker
Saprolegniaceae, p. 165. 1923.
Isolates of A. pa ra siticus occur only. rarely. Since the
original diagnosis , based on an isolate from North Carolina
( Coker, 1923), it has been .reported only from Massachusetts
( Johnson, 1956) and from Illinois ( Beneke , 1948a ). This
species may be distinguished from other parasitic species of
Aphanomyc es by its endobiotic and ornamented oogonia which
always form within the host filament and which have numerous
spines up to 8 pm in length. Isolates of A. pa ra siticus were
not found during the course of this investigation. 32
Genus : Ach l� C. G. Nees
tJova Acta Ac ad. Leop. -Carol . , 11: 514. 182 3.
The genus Achlva is the largest and the bes t known genus of the water molds ; it consiDts of more than one hundred species and varieties . The zoosporangia are usually clavate, naviculate, or fusiform; they are usually terminal and of greater diameter than the subtending hyphae and are renewed by sympodial branching . Zoosporangial renewal by cymos e branching and basipetalous succession can occur in various species of Achlva with varying frequency. Zoospore discharge is termed achlyoid and involves the immediate encystment of the primary zoospores in a hollow ma ss at the mouth of the zoosporangium. Most isolates of Achlvn are readily recognized by the type of zoospore discharge exhibited and/or by the occurrence of 11ghosts11 , the emp ty primary zoospore cysts left behind following the emergence of the secondary zoospore.
Under unfavorable cultural conditions , zoospore discharge may be aplanoid , thraustothecoid, or dictyoid . The secondary zoospores swim actively, later encyst, and _upon germination develop into mycelium. Gemmae may or may not be present .
As in most genera of water molds , isolates of Ach lva may fail to form sexual structures , even after prolonged growth in culture and despite the use of various methods to induce the formation of sex organs. Such isolates may be ma le or female strains of a dioecious species and may be readily identified following cross-cultural studies . Key to the Illinois Species of Ach��
. . . 1. Oogonial wall smooth • • • • • • • • • • • . . . . . 2
. 1. Oogonial wall conspicuously ornamented . . . • • 21
2. Thallus dioecious •• •••••••••• •••••••3
2. no us ...... Thallus mo ecio • • •• ...... 4
3. Spherical , thick-walled gemmae present ; oospores rarely
maturin 3. Spherical , thick-walled gernmae entirely absent ; oospores . . usually maturing • • • • . . • • • A. ambisexualis._, p. 37 4. Antheridial branches lacking (Fig. 73) ...... ...... ••••••••••••A. carolinian� , p. 38 4. Antheridial branches present . . ,, ...... 5 5. Antheridial branches monoclinous or androgynous ••••••6 . 5. Antheridial branches diclinous • • • • • • • . • 12 . . . 6. Oospores centric or subcentric • ...... 7 . . . 6. Oospores eccentric • • ...... 9 7. Oospores centric ; oogonial wa ll pitted only under point of antheridial attachment (Figs . 79, 80) • • A. Ea cemosa , p. 38 7. Oospores subcentric ; oogonial wall unpitted or pitted only under point of antheridial attachment • • • • • • • • • • • 8 8. Oogonia mostly apiculate (Fig. 82 ) ••A. �pi culata, p. 39 8. Oogonia not apiculate (Fig. 85 ) •••A. po ly?ndra, p. 39 9. Oospores mostly 1-3 per oogonium; oogonial stalks frequently . . . . recurved (Fig. 90 ) •••• . . . . . !::_. ?r ion, p. 40 9. Oospores usually more than 3 per oogonium; oogonial stalks . . . . • not recurved • • ...... • • • • • • • 10 34 10. Oogonial wall unpitted , smooth ; antheridial branches strictly �onoclinous • • • • • • • A. �e barvana , p. 40 10. Oogonial \'Jal 1 pitted , smooth ; antheridial branches usually monoclinous • ...... 11 11. Oospheres usua lly maturing ; oospores small and numerous, filling the oogonium; oogonia conspicuously pitted; antheridial branches 1�1onoc linous (Fi ...... 11. Oospheres rarely maturing ; oospores small and numerous not fil ling the oogonium; oogonia pitted only under the point of ant�eridial attachment ; antheridial branches monoclinous a�d androgynous (Fig . 99) ••A. �o nspicua , p. 42 12 . Oospores subcentric • • • • • • • • A. 9b lon_g_ata , p. 42 12 . Oospores eccentric • • • • . . . . • • • 13 13. Primary zoosporangial discharge as in Thraustothec� (Fig. 102) •••••••••••••••••A. _9ul:>ia , p. 42 13. Primary zoosporangial discharge never thraustothecoid •• 14 14. Oogonia usually lobed , hemispherical or otherwise irregular in shape • • • • • • • • A. intr�cata, p. 43 14 . Oogonia usually spherical or pyriform • • • • • • • 15 15. Antheridial branches coiling closely about the hyp�ae which may or may not bear oogonia (Fig . 107) ••••••••••• • • • • • • • • • • • • • • • • • • A. pr oliferoides , p. 44 15. Antheridial branches not coiling about the hyphae • • ••16 16. Vegetativ8 hyphae with numerous conspicuously inflated lateral swel lings (Fig. 109 ) •• . . A. diffusa, p. 44 16. Hyph al swel lings entirely absent • . . . • • • • • • 17 35 17. Oospheres not tGaturing ; oospores not filling the oo�onium (Fig. 116 ) ••••••••• • • • • • J. 7. Oospheres maturing ; oospores filling the oogonium • • • • 18 18 . Oospores few in number , mostly 1-2 . . . . . • • • • flt ...... 18. Oospores numerous , mostly 2-10 •• ...... • • • 19 19. Antheridial branches strictly dicl inous , irreqular , contorted, profusely branched , wrapping about the oogonium and oogonial stalk • • • • • • • A. 9r olifer�, p. 46 19 . Antheridial branches usually diclinous , occasionally monoclinous , simple or branched, not contorted or wrapping about oogonium • ...... 0 • • • • • • • • • 20 20. Antheridial branches usually diclinous , occasionally remotely monoclinous , simp le or sparingly branched and always attached to the oogonium (Figs . 117, 118 ) • • . . . . • • • • ...... A. �ebsiana , p. 47 20. Antheridial branches usually diclinous , occasionally monoclinous , branched, and frequently not attached • • • • • to the oogonium (Fig. 113 ) A --�----flanel lata, p. 45 21. Oospores centric or su�centric • • . . . • • • • • • • • 22 J... • 21. Oospores eccenL..rl.c • • • • • • • • . . • • • • • • • 27 22. Oospores centric ; •••••••••••••••••23 22. Oospores subcentric • • • • • # ...... • • 26 23. Oogonial wall pitted only under poi · of antheridial attachment , antheridial branches mo _· ,.y androgynous (Fig. 123) •• ...... A. colorata, p. 48 23. Oogonial wall unpitted , antheridial branches absent or, when present , mo stly monoclinous •••••• ...... 24 36 24 . Oogonial stalks generally coil ed ; antheridia absent or , if presc:nt , of monoclinous oJ.:-igin • $ • • • • ...... ••A. soirRcaulis , p. 48 24. Oogonial stalks generally not coiled ; antheridia present and generally of rnonoclinous origin • • • • 25 25. Oogonial wall densely ornamented (Fig . 125 ) ...... • • • • • • • • • • •••••••••• .l\ . J?_§lEi llo.sa, p. 50 25. Oogonial wall smooth or but sparsely ornamented •••••• ...... 26. Oogonial wall unpitted ·with mammiform ornamentations (Fig. 129 ) ••••••...... 26. Oogonial wall pitted with papillate ornamentations (Fig . 133 ) • • • • • • • • • • • • • • A. �r eleas_.9a n�, p. 52 27. Oogonial wall with truncate pro jections ; antheridia mostly androgynous (Fig . 138) ••••••••••A. recurv�, p. 53 27. Oogonial wall with papillate, tubercul ate , or variously shaped projections , not truncate • • • • • • • • • • • • 28 28. Oospores single ; oogonia� stalks much-branched and contorted ; untheridia usually absent , or , when present , of androgynous or monoclinous origin • • • • • • • • • • • • • • • • • • • • • • • • • • • A. _g].o merat2 , p. 53 28. Oospores numerous ; oogonial stalks simple or once branched ; antheridia absent , or, when present , of monoclinous or diclinous origin (Fig . 144 ) •••••• • • • • • • • • • • • • • • • • • • A. crenulata, p. 54 37 l\ chlvc1 bisexualis Coker and A. Couch J. Elisha Mitch . Sci . Soc., 42 : 207. 1927. Among those dioccious species of �chlya_ with eccentric oospores , Achly� pise�uali� may be readi ly recognized by the abundant spher ica l gemmae that are formed by the ma le and female thalli1 either singly or catenulate (in chains), by the moderately abundant , lateral , smooth -wa l led oogonia that are pitted only under the attached antheridial cells, and by the long , profusely branched antheridial branches which wrap around the oogonia. The oospheres general ly do not mature , and the oospores usual ly do not fill the oogonium. Beneke (1948a) ho� reported the occurrence of A. bisexualis from Illinois . Efforts to induce sexual structures were not successful during the course of this investigation. Achlya ambisexualis J. R. Raper Amer. J. Bot. , 26: 639 . 1939 . Achl� ambisexualis may be distinguished by the abundant , laterc:l or terminal, smooth-walled oogonia that are pitted only under the point of the attached antheridial cell, and by the long , profusely branched antheridial branches which wrap around the oogonia and attendant hyphae. The oospheres generally mature , and the oospores fill the oogonium. Achlya ambisexualis differs from A. bisexualis in forming oospheres which mature and oospores which £ill the oogonium. Isolates of A. ambisexua lis have been reported from Illinois by Beneke (1948a). Isolates of A. ambisexualis were not found during the course of this investigation. 38 ·1\ch- -l'1u--- --·-·-·-·caro::!.. in=. • • , : • • Bot Gaz 5 0 3 81 1. 91. 0 ( F :l.gs • 7 3 - 7 6 ) Isolates of A. ca£2}_ini:an� may be distinguished by the abundant , smooth-walled (occ<:isionally spdrsely papill ate ), usually unpitted oogonia bc rne laterally on slender stalks that are generally in length about twice the dinmeter of the oogonium and by the lack of antheridial branches (Figs . 73, 74 ). When present , antheridial branches are sparse, monoclinous or diclinous, delicate , often irregularly branched , and generally not attac11ed to the oogonia or , if so , are non- functional (Fig. 75 ). Isolates of A. caroliniana form oospheres which usually mature (Fig. 73). The eccentric oospores do not generally fill the oogonium (Fig. 76). Although A. caroliniana is widespread in its distribution (Johnson, 1956), this species has not previously been reported from Illinois. �chlya race�osa Hildebrand Jahrb. wiss. Bot ., 6: 249. 1867-68. (Figs . 77-80 ) Isolates of A. racemosa are readily recognized by the abundant , smooth-walled , unpitted oogonia containing centric oospores and by the androgynous antheridial branches (Figs . 79 , 80). The oospheres of A. racemosa always mature , and the subsequent oospores generally do not fill the oogonium. According to Johnson (1956), Achlva rac�mo sa is of frequent occurrence and is widely distributed throughout the world. 39 Isolates of this species huve been reported from Illinois by Bretsnyder ( 1943) and I3enek.e ( 1948a ). Beneke also identified an isol 2te of -A. __soarr ...... _____ owii, _ a species distinguishable from A. Ea cerr..!Q�..9.. by its larger oospore size. Since these isolates do not differ significantly in other respect�, there is little justification, as Johnson (1956) has already suggested , for retaining -A. ------soarrowii as a distinct species . Bot. Zeit. , : 635. 1888. (Figs . 81-84 ) Typical isolates of A. apicula_t a may be dis ti�guished by their smooth-walled oogonia, many of which have a conspicuous apical papillus and contain subcentric oospores (Figs . 82, 84 ). Oogonia may vary in abundance , and the percentage of non- apiculate oogonia may vary considerably from one isolate to another (Fig. 83 ). All isolates , however , e)�hibi t a predominance of apiculate oogonia. The stout oogonial stalks may be bent , curved , or once-coile� (Fig . 81). Antheridial branch origin is usually mo noclinous or androgynous (Fig. 83 ). Although A. ap iculata is of quite common occurrence in the United States (Johnson , 1956) , this is the first report of its occurrence from Illinois . Achlya po lyandra Hildebrand Jahrb. wiss. Bot ., 6: 258. 1867-68. (Figs . 85-88 ) Isolates of A. po lvandra may be readily recognized by the long , stout , bent or curved oogonial stalks , by the 40 subccntric oosporcs , and by the antheridial branches that are predominantly androgynous (Pigs . 85 , 88). The subcentric oospores rarely fill the oogonium. Isolates of A. po lvandra have been reported previously from the United States only from Michigan and Massachusetts (Johnson , 19 56) . This is the first report of A. oolvandra from Illinois . AchJ.::..'L� orion Coker and Couch Saprolegniaceae, p. 112 . 1923. (Figs . 89-92) Among those species of Ach�E with eccentric oospores , AchJ.va orion may be distinguished by the abundant , lateral oogonia that are smooth-walled and pitted under the antheridial cell (occasionally elsewhere), and by the usually bent , curved, or recurved oogonial stalks (Figs . 89 , 92 ). The antheridial branches are usually androgynous (Fig. 90 ). The oospheres , numbering from 1-12 (generally 1-3 per oogonium) usually mature; the subsequent oospores fill the oogonium (Fig. 92 ). Isolates of A. orion have been reported from Illinois by Beneke (1948a) and by Overman (1970). Achl e ar a Humphrey y� d b yan_ Trans . Amer . Phil . Soc. , 17: 117. 1893. Achlya deb a�.!@. is remarkably similar to A. americana and may be distinguished from that species only by the unpitted nature of the oogonial walls and by the somewhat longer , branched, often contorted , monoclinous antheridial branches that have their origin remote from the oogonium to which they are attached. Since 41 in some isolates of !\. _?m�r is:_ana the pi ts may be inconspicuou:::; or possibly lacking in some oogonia , the only practical basis for separation is to de terr.tine the origin of tl1e antheridial branches . The determination of antheridial branch origin, whether close to or remote from the ooaonial� stalk, mav� in itself become a judgment decision for the observer , and , therefore , renders po sitive identification of A. debaryana even more difficult and open to question . Although apparently widespread in distribution, A. ?e baryana has not been reported from the United States (Johnson, 1956) • .A chlya �-�.§!E_�s._a na Humphrey Trans . !�mer. Phil. Soc. , 17: 116. 1893. (Figs . 93-96 ) Typical isolates of A. americana may be distinguished by the abundant , conspicuous ly pitted , smooth-walled oogonia generally filled with numerous small eccentric oospores (Fig. 96) , and by the simple antheridial branches that are mos tly monoclinous , with their origin close to the oogonium to which they are attached (Fig. 95 ). In such isolates the oospheres normally mature . Certain isolates of A. americana may exhibit considerable variation in the appearance of the pits in the oogonial walls , even in the same culture. In such cases it may become quite difficult to distinguish A. americana from A. debarvana (see discussion under that species ). Isolates of A. americana have been reported from Illinois by Bretsnyder (1943 ), Beneke (1948a ) and Overman (1970). 42 Achl ya con:.;_oicua Coker. Saprolcg�iaccae, p. 131. 1923. (Figs . 97-100) Achlva consoicuQ may be distinguished by the moderately abundant , lateral oogonia that are smootll--walled and pitted under the antheridial cell , or, occa8ionally elsewhere (Figs . 98, 100). The oosphcres rarely mciture in A. C 99). The simple or sparingly branched antheridial branches may be either monoclinous or androgynous , or , rarGly, diclinous (Figs . 97, 98). Isolates of A. conspicua have been reported from Illinois by Deneke (1948a) and Overman (1970). Achly� oblonga ta de Bary Bo t. Zeit., 46: 64 6. 1888. Achlya oblonga ta may be recognized from other subcentric species of !-c hlva by the abundant smooth-wa lled oogonia that are unpitted, and by the simple or sparingly branched diclinous antheridial branches . The oospheres mature infrequently, and the oospores generally do not fill the oogonium. This species has not been previously reported from Illinois . Efforts to induce sexual structures were not successful during the course of this investigation. Achlya dubia Coker Saprolegniaceae , p. 135. 1923. (Figs . 101-104 ) Among those species of !ic� with eccentric oospores , A. dubia may be distinguished by the thraustothecoid discharge 43 from the primary zoosporangia (Pig . 102 ), by the abundant lateral oogonia which are smooth-wa lled and pitted or pitted only under the point of attachment of the antheridial cells, and by the sparingly branched diclinous antheridial branches n (Fig. 103 ). ThP. oospheres generally mature and the s ubseque t oospores usually do not fill the oogonium (Pig. 104). This is the first report of A. dubia from Illinois . Ac�� intric�t a Beneke J. Eli� ha Viitch. Sci. Soc., 64 : 261. 1948. Achlv� inj:ricata may be distinguished from other eccentric species of Achlva by its formation of lobed and irregularly shaped oogonia . The oogonia are spars�, latent in their development, and are limited in their formation to a narrow zone close to the substratum, often an area heavily fouled by other microorganisms . A. intricata apparently is of rare occurrence . Other than the original description of the species from I llinois (Beneke , 1948b ), isolates of A. intricata have been reported only from Texas (Johnson, 1956) and Iceland (Howard et al, 1970). In describing a new species of Achl� from Illinois , Beneke (1948a ) applied the epithet !:_. contort�. Since this particular specific epitb.et had been used previousl y by Cornu in 1872 (Johnson , 195G) , Beneke (1948b) changed the epithet to A. intricata . Efforts to induce sexual structures were not successful during the course of this investigation. 44 3aprolc9ui2ceae , p . 115. 1923. (Figs . 105-108) A Isolates of • .e_r oliferC?i de� 2re dis tinguishable from A. flacellata o� the bcsis of their coiling antheridial branches (Figs . 106 , 107). When initially isolated in gross culture, the long , contorted , much branched dicJ. inous antheridic:il branches coil about the hyphae and the oogonia that they are bearing. This distinguishing feature is gradually lost with repeated subculturing and may disappear entirely. The validity of fl.• I?.EElif�r oi latter species. Beneke ( 1948a ) has reported the frequent occurrence of A. oroliferoides. - in Illinois . Achlva diffusa (Harvey) Johnson The Genus Achlva, p. 64 . 1956. ( Figs . 109-112) Among species of Ac.hl va with eccentric oospores , isolate:::; of A. diffusa arc easily recognized by the very large "balloon- like'' inflated swellings that occur in abundance laterally on the hyphae (Fig. 109). These swellings are usually found intermingled with the oogonia but may occur singly on the vegetative hyphae. They are usually spherical or subglobose in shape and may reach a diameter of 250 pm. The exact nature of such hyphal swellings is not known. The contents do not 45 cleave into oospheres nor do they function as zoosporangia or germinate into new hyphae in the manner of gemmae. Another diagnostic characteristic of A. diffusa is the abortive oospheres and oospores (Fig. 111) . This is the first report of A. diffusa from Illino is . Achl_� flaoellata Coker Saprolegniaceae , p. 116. 1923. (Figs . 1'13-116) Isolates of A. f l a oe ll�l:� may be recognized by the abundant , smooth-walled oogonia containing eccentric oospores, and by long antheridial branches that are usually profusely branched and mostly diclinous in origin (Figs . 113, 115). In such isolates the oospheres usually do not mature, and the subsequent oospores do not fill the oogonium (Fig. 116). Beneke (1948a ) reported numerous isolates of A. _?.mperfes:t a Coker from Illinois , a species distinct from A. flagellata by its oospheres , which frequently fail to develop into mature oospores and by its antheridial branches which are sparsely branched and frequently monoclinous and/or androgynous . Since these features are common to both A. flagellata or A. imperfecta, those species former ly identified as Achlya �erfecta Coker are more appropriately identified as A. flaaellata . A. flagellata is widespread in its distribution and is among the more frequently encountered member of the genus (Johnson , 1956). Bretsnyder (1943 ), Beneke (1948a ) and Overman (1970) have reported A. flaqellata from Illinois . L!. 6 J:·:ycologia, ]_� : 2 74 . 1941. Isolates of A. may be recogn zed by their rocl.-!='_i0ueziClt?-a i abundant , lateral, unpitted oogonia containing but one or two eccentric oo spor�s per oogonium, and by the diclinous antheridial branches. The oosphercs usually mature , though the oospores generally do not :Cill the oogonium . In the number of oospore s , !:_. rodrigueziana rc::;enfules A . or5_01!_, but in the latter species the antheridial branches are usually androgynm.:s. Beneke ( ·1948a) has reported the occurrence of this s ecies from I l n is rodrinue�dana p l i o . Isc lates of A. ------were not found during the course of thi s inves t igat ion . Nova Acta �cad. Leop .-Carol. , 1� : 514. 1823. Among those species of Achl� with eccentric oospores , e A. oro l if ra may be distinguished by the l arge pitted oogonia with numerous small oospores , and by the antheridial branches which are s trict ly diclinous and which exhibit a strong tendency to wrap around the oogonium and attendant hyphae . The oospheres usually mature and the oo spores fill the oogonium. Howard et al. (1970) have reported isolates from Iceland that have smaller (mostly 40-85 pm) , unpitted oogonia and have proposed a taxonomic change to reflect these variations . A. pro l ifera resembles most closely those isolates of A. pr oliferoides with coiling antheridial branches , p itted or unpitted oogonial walls, and oospores that number usually 47 4- 10 and are mo stly 20-25 pm in diameter . Isolate0 of A. Ero l�feroides , however , are not strictly diclinous , the coiling tendency may disappear under cultural conditions , and the antheridial cells are attached to the oogonial wall by projection.3 . Isolates of A. r.£9l�:fer� have been previously reported from Illinois by Beneke (1948a ) and Overman (1970). Efforts to induce sexual structures were not successful during the course of this investigation. �c hJ.\� kleb��an� Pieters Bo t. Gaz. , 60_: 486 . 1915. (Figs . 117-120 ) Isolates of A. �l ebsiana may be recognized hy the abundant , smooth-walled oogoniu , which are usually pitted only under the attached antheridial cell (Fig. 117), by the small eccentric oospores that generally fill the oogonium (Figs . 119 , 120), and by the antheridial br2nches that are predominantly diclinous in origin but may be remotely monoclinous as well (Figs . 117, 118). A. klebsiana belongs to a species complex that also includes A. americana and A. debarvana . Because of the ------ considerable variation in the nature of the pitting of the oogonial wall and/or in the origin of the anthcridial branches , some authors believe that A. klebsiana and A. deba£Y_a...I.:� are synonymous (.Johnson, 1956 ). Those isolates utilized for this photomicrographic guide exhiDitcd 48 considerable variation in the ratio of diclinou3 anti1eridial branches to those of remotely rnonoc l inous origin. In all such isolates , however , tho�e of diclinous origin were predominant. Isolotes of A. l-::le:;::;ia!1a heve been reported :from Illinois by Bretsnyder (1943 ), Deneke (1948a ) and Overman (1970). --�-Achlva ·-----·---colorata Pringsheim Sitzungsber. Akad. Berlin , p. 889 . 1882 . (Figs . 121-124 ) Isolates of A. colorQ t a may be distinguished from those of A. f_?_�__emsisa primari l y on the basis of their papill2te oogonia ( Fig . 121) . �he abundant , lateral oogonia are 9itted under the attached antheridial cells , und the antheridial branch origin is androgynous (Pig. 123) or , rarely, exigynou s (Fig. 124). The oospheres infrequently mature and the centric oospores generally fill the oogoniun (Figs. 122, 123 ). The specific status of A. colorQta is debatable since the studies of Reischer (1949 ) indicate that the presence or ubsence of oogonial wall ornamentation is dependent on temperature. A careful study of the morphological and physiological features of a large number of isolates of both A. colorata and A. racemosa seems to be the only means of solving this taxonomic probler;i. Bret snyder ( 1943) and Beneke ( 1948a ) have previously reported this species from Illinois . Ach lya spiracaulis Johnson Mycologia , 41: 67'2. 1.949. Isolates of A. spiracaul is are readily dist inguished from other species with centric oospores by the presence of densely 49 papillate oogonia terminating long coiled oogonial stalks , and by the usual absence o= antheridial branches. The extreme variability of !2· �iruc_C;lulis under cultural conditions has been noted by previous investigators (Johnson, 1949 ; Howard et al, 1970). It is apparent thut certain isolates of A. �i racaulis are remarkably similar to both A. p� i llosa_ Humphrey and A. oligacan_-t:._h a de Bary. The principle distinguishing characteristics used to separate A. spiracaulis from A • .E_3Pillos� include more densely papillate oogonia and the absence of coiled oogonial stalks in the latter species . A. pa oillosa is said to form mostly monoclinous antheridial branches , with the antheridial cell abstricted but usually non-functional. Howard et al. (lee . cit.) have reported considerable variation among isolates of A. spiracaulis in the density of oogonial wall ornamentation and in the origin of antheridial branches and function of the antheridial cell; they also reported a strong tendency of this organism to lose the coiled oogonial stalks after prolonged culture. The principle distinguishing characteristics used to A. separate spi ra�aulis and A. oligacantha include smooth- walled or only sparsely papillate oogonia and oogonial stalks that are infrequently coiled in the latter species. The antheridial branch origin in A. oliga canth� is mostly monoclinous with the ar.theridial cell abstricted and functional. The oospheres are said to mature only very rarely. The isolates of A. �acaulis reported by Howard et al (loc. cit. ) bear 50 n a s tro g resen�biance to !:.·.· Q_l igacant_b� in the nature of tl:e oogonial \·JaJ 1, the origin of the anther idia l branches and function of the antheridial cell , and in the abser-ce of coiled oogonial stalks after prolonged culture . Isolates referable to the A. -�p iracauli;, - A. papi l�o _3 a - - relativelv A. _oli _.....__aacan___tha �pecies-comolex are - rare in occurrence but are apparently widespr�.: ad in distribution. A. �aca'::ll is has been reported previously from flichigan and Louisiana (Johnson, 1956 ) and from Iceland C-rownrd et al, 1970) ; A. £.�_pillosa from Californ ia , �a ssachusetts , �ichigan , Peru , Japan, and Europe , and Russia (Johnson , 19 56). Isolates of A. spiracauli� have not been previously re�orted from Illinois . Efforts to induce sexual structures were not successful during the course of this investigation Achlya papillosa llumphrey Trans . Amer . Phil . Soc., 17: 125 . 1893. (Figs . 125-128) Achly� paRi_llos� may be readily distinguished from other centric species of Achlva by the moderately abundant , densely papillate or tuberculate, unpitted oogonia (Fig. 12 5) and by the sparingly branched monoclinous antheridial branches (Fig . 127). The oospheres generally mature , and the oospores do not fill the oogonium (Fig. 128 ). This is the first report of A. Ea�i l los a from Illino is . In one isolate of A. pa oillosa utilized for this photo- e micrographic guid , the oogonia produced were smooth-walled , !:) 1 sparsely papillate1 or densely papillate. This isolate seems to have cliaracteristics of both A. olioacantha (smooth-walled or sparsely papillate oogonia ) and /\. pa oillosa (densely papil late oogonia ). Since previous studies have sl1own that the presence or absence of oogonial wall ornanentation is dependent on temperature (Reischer , 1949 ), a careful study of the morphologicnl and physiological characteristics of a large number of isolates of both species seems to be the only means of solving this taxonomic pro�lem. Because of the predominance of oogonia with densely papillate oogonial walls (Fig. 1� 5) and with monoclinous antheridial branche3 (Fig . 127), the isolate included in this photomicrographic guide is tentatively classified as A. �o illC?s a Humphrey. Achlva oliga�antha de Bary Bot . Zeit., 46: 64 7. 1888 . Isolates of A. olicacantha may be distinguished from other centric species of __Achlva ...... __ by their abundant lateral or terminal, unpitted , smooth-walled or sparsely ornamented oogonia borne on infrequently sparingly coiled oogonial stalks , and by the monoclinous antheridial branche5 on which antheridial cells are abstricted and functional. The oospheres mature extremely rarely, and the oospores only occasionally fill the oogonium (see discussion under A. papillosa Humpr1rey and A. 3?iracaulis Johnson). Isolates of A. olioacantha have not been previously reported from Illinois . Efforts to induce sexual structures were not successful during the course of this investigation. 52 AchJ.va radiosa f'iuurizio Hittheil . Deut:-, cl 1. F ishc�1crei-Ver.eins , 7: 5 7. 1899 . ( Figs . 129-132) Isolates of II .. radi�� s� may be readily recognized by the abundant , lateral, unpitted oogonia that have mammiform or papillate orna�entations and by the androgynous anthcridial branches (Figs . 129 , 130). The oospheres usually muture , and the subcentric oospores generally do not fill the oogonium (Fig. 132). This is the first report of l\. radios0:_ from Illinois . Ach� _!:r�_!_�aseana (Humphrey) Kauffman Ann . Rept . Iiich . l\ Cnd. Sci., Arts and Letters , 8: 26. 1906 . (Figs . 133-136) Among species of Achlya with subccntric oospores , A. trelease?na may be distinguished by the extreme rarity of zoosporangia , and by the very abundant and easily recognized oogonia. The zoosporangia , which are usually entirely absent under tl1e usual cultural conditions , may be induced by special treatment (Johnson , 1956). When formed , the zoosporangia may discharge in an aplanoid manner or, more frequent ly, in an achlyoid manner . In the latter case, the primary zoospore cyst cluster is not persistent at the exit pore . Such variations from the typical achlyoid condition may suggest a relationship \·Ji th the genera Aplanes and Saorol�nia , and may result in a mistaken identification. The oogonia of A. treleaseana are very abundant , densely ornamented with papillate projections , usually intercalary or 53 a terminal and do l iform or spheric l , and often occur in chains (Figs . 133 , 134 , 135 ). The oospheres genera lly mature and the subcentric oospores fill the oogonium (Fig . 136). This is the first report of this species from Illinois . !�<; _h l ya r���r�a Cornu Ann . Sci . Nat. Bo t. , Ser . v, 15 : 22. 1.8 72. ( Figs. 137-1.4 0) Isolc�tes of 1\ . re�u r_ ya may be distinguished by the abundant , lateral , unpitted oogonia that are covered with de�se truncate ornamentat ions , by t11e recurved or bent oogonial stalks , and by the androgynous antheridial branches (Figs . 138 , 139). The oospheres generally mature , and the eccentric oospores fill the 1 oogonium (Fig. 140 ). Tl is is the fir�t reoort of the occurrence of A. recurva from Illinois . Achlya alomerata Coker Myco logia , 4: 325 . 1912 . Achlya gl omerata may be recognized by the abundant , lateral , unpitted oogonia with papillate or tuberculate ornamentations borne on oogonial stalks that are much branched and glomerulate and by the usual lack of antheridial branches . When present , the antheridial branches are mostly of androgynous or monoclinot:1 s origin. The oospheres mature and the oospores fill the oogonium. Isolates of A. g!omerata have not been previously reported from Illinois . Efforts to induce sexual structures were not successful during the course of this investigation. 5'1 " .... . - CJ. '- U ..:.� 1' rh 1 - i..� ... e.. (.,._; l r.ir � c rentl ] ,.., J_ ,.., ? i J.!ycologic:i, 40 : 336. 1948. ( Figs • '14 1- ".It1 � ) Among thos0 species of �i._chlv.::i with eccentric oosr;ores , A. crenulata msv be readily recognized by its abundant , lateral , unpitted (or sparsely pitted ) oogonia with crenulate , papillatc, or tuberculate ornamentations , and by the lack of 2ntheridial branches . The oospheres usually mature , and the oospore3 fill the oogonium ( Figs . 142 , 143 , 144). This is the first repor t of the occurrence of J\. crenulata from Illinois . Genus : Protoachlva Coker Saprole9niaceae, p. 90 . 192 3 . The genus Pi :-otoac� was estc:iblished to include those species with characteristics of both Sapro legnia and Achlya . The features used to distinguish the genus are physiologically stable and apparently do not vary with changing environmental circumstances (Lounsbury, 1930). The mycelium formed by species of P�9_toa_c h lya is more delicate than that of Ach1v�, with mostly clavate to cylindric�l zoosporangia usually renewed by cymose branching , as in j', chlya (Fig. 146) , but also , less frequently, by internal proliferation (Fig. 147). Zoospores are diplanetic , and some , upon emerging, swim away prior to encystment, as in Sapro leonia , while others from the same zoosporangium encyst at the mouth of the zoosporangiurn, as in Ac.hl:Y_�. Oogonia are borne on short , lateral stalks , generally singly, and form a few centric oospores per oogonium. 55 Key to the Illinois Species of" PJ�o t oach_ly a 1. Antheridia mostly diclinous •••••••P. £a�a��xa, p. 55 1. Antheri.dic; mostly hypogynous (Fig. 14 8) • P. h:Lpo_gyn� , p. 55 Protoachl_va par2doxa (Coker ) Coker Saprolegniaceae , p. 91. 1923. Isolates of P. 2aradoxa may be distinguished by their smooth-vrnl led, usually pitted oogonia containing f eH ( 2-4 ) centric oospores borne on short lateral branches ; and by the usually diclinous antheridial branches which occasionally tend to coil about the oogonia and adj acent hyphae. Deneke (1948a ) reported the occurrence of this species from Illinois. Efforts to induce sexual structures were not successful during the course of this investigation. !'r otoachlya hypogyna Shanor and Conover Amer. I,1idland Hat . , 28: 74 6. 1942. (Figs . 14 5-152) Isolates of �· hypoqvna may be readily recognized by I their unpitted, smooth-walled oogonia (occasionally with a few papillations ) borne on short lateral branches containing usually one or two centric oospores , and by the hypogynous antheridial cells (Figs . 148, 149) , or , occasionally, by the presence of monoclinous or diclinous antheridial branches (Figs. 150, 151 ). Isolates of P • .b_ypogvna have been reported from Illinois by Beneke (1948a ). 56 � Genus : -Aolanes de Barv Bot. Zeit ., 46: 613 , 650. 1888. 'I'he via::; established to include those genus �}m_!_e�. saprolegniaccous fungi in which the pri�ary zoospores are retained in the zoosporangium , germinating there by the formation of germ tubes that grow outward through the zoosporc:jngial wa ll (Fig . 153 ). In iso lates of !.P .l-.9-. I�� ' the zoosporangia tend to be very scarce or often entirely absent for long periods of time in culture . The myceliur.1 of J\pl c:;ncs resembles that found in certa in isolates of Achlva . The oogonia are abund ant , often formed in chains , may be either barrel-shaped or spherical, and llave greatly thickened and heavily pitted walls. In all isolates of Aolanes which have received careful study , achiyoid and/or s aprolegnoid as well as ap l anoid zoospore discharge has been observed. Furthermore, in many well-defined sp�cies of !>ch lya and Sapr�}.e q0i.E. as well as those of other saprolegniaceous genera , aplanoid zoospore discharae- mav- occur under abnormal. environm2ntal condition3 . Johnson (1956) has clearly demonstrated that the most common species , Ap�a n� �_Feleaseanus , is a species of Achly� It is quite possible that the remaining species of ' after thorough study, may belong to either Achlya or Saproleqnia . Ti1e validity of the genus Apl ane� at present rests upon b·JO doubtful criteria ; the absence or rarity of zoosporangia , and the germinatj on of zoospores l:-n situ_. The only species knmvn from Illinois is A. androgv nus . 57 '£rans . ;,mer . Phil . Soc . , J.2 : 134. 1892. (Figs . 153-156) Isolates of A. �ndroavnus may be readily recognized by their abundant , spherical (often barrel-shaped ), greatly thickened , heavily oitted oogonia formed singly or in cl1ains (Fig. 155), and by the monoclinous antheridial branches (Fig. 154 ). The oogonia generally contain numerous suhcentric or centric oospores (Fig. 156). This is the first report of the occurrence of androovnus from Illinois . A. _____ , ___ In an effort to induce the zoosporangial st age , the method employed by ,Johnson ( 1956) with Achl va trele�-::>�a n� ( Humphrey) Kauffman was utilized in this study with {:p_�..§l_l!e s s androq_y_n._'fS . Three different i olates of A. _a_�dr.££.L..r:..�s_ were grown in distilled water adjusted with a pH meter to the desired pH, from a range of pH 2 to pH 10 at increments of O. 5, by using O. 1 i'i sulfuric acid and 0. 1 N sodium hydroxide. The cultures were incucated at ro om temperature (22-26 C) and examined over a period of three weeks . After three successive tests over this pH range, nothing more than an occasional aplanoid zoosporangium was induced. A larger num.'Jer o:f isolates and, quite possibly, the use of an isolate of Achlva treleaseana as ?. control �ay have yielded more informative results . 58 Tran:'3. Am. Phil. Soc. , }7 : 131. '1 893. The ge:nus :?-.:l'..:....r2_usto:':: !-:�_s:a \·1as e3tablished to include those species in which the primary zoospores encyst within the zoosporangium and are liberated by the dissolution of the zoosporangial wall (Fig . 157). The encysted primary zoospores may separate and passively drift away or may remain clumped together , in part retaining the same general shape as the original zoosporangium. The zoosporangia are clavate to cylindrical but usually exhibit a strong tendency toward the stout club-shaped form (Figs . 157, 162). The zoosporangia are renewed from belov1 , as in !'·c��a and ·::he mycel ium resenl: les All of the isolates o-: 'Ehraustotheca for;n abundant oogonia and antheridia in culture ; the oogonia have several to many eccentric oospores (Figs . 160 , 164 ). Key to the Illinois Soecies� of ------Thraustotheca·--- 1. All zoosporangia of the thraustothecoid type ; oogonial wall smooth (Figs . 157, 159) • . . . . . 1. Primary zoosporangia achlyoi-0 , s e condary zoosporangia thraustothecoid ; oogonial wall ornamented (Figs . 161, 162 , 163 ) •••••• • • • • • • • • • • • ------·Thraustotheca clav -----ata (de Sary) Humohrey • Trans Amer. . Ph il. Soc., _17 : 131. 1893 . (Figs . 157-160) Isolates of T. clav�ta may be recognized by their abundant , smooth-walled oogonia containing from 1-10 eccentric oospores 59 and borne singly on short lateral s ta l ks , and by their diclinouG antheridicl branch0s (Fig�;. ·1 :>9, 160). Denel::e ( 19'18a) has reported the occurrence of T. clavnta from Illinois . J. ::::1 is ha !·�itch . Sci. Soc . , 40: 198 . 19?.4 . (Figs . 161.- 164 ) Isolate�..; of 'i' . priE! 164) , and by their inonoclinou::> antheridial branches O, ig. 163) . Beneke ( 1948a ) and Overman ( 19 70) have reported T. pr imoaci1l_ya from Illinois . J. Elisha �itch. Sci. Soc. , 42: 2 19 . 1927. (Figs . 165-168 ) The genus CuJ:.Y.J?..t:El��a includes a group of water molds that are of rare occurrence. In· isolates of CalyE,tralean�-� the primary zoospore discharge is accomplished by the rupture of the zoosporangial wall; the terminal portion of the zoosporangium completel;r breaks off (Fig. 165) . The primary zoospores encyst within the cylindrical zoosporangium, are liberated in clumps , and float passively away following the dehiscence of the zoosporangial tip . Later , the zoospores of the secondary type emerge from the primary zoospore cysts. Oogonia are formed quite readily in culture. These are usuully 60 smooth-walled , t11ough occasionnl papillated oogonia do appear with one or two papillations ; they contain one to many centric , 167, 168 ). subcentric, or eccentric oospores (Figs . Antheridia are generaily androgynous , though rnonoclinous anther:i..dial branches do occur (Fig. 166 ). Only the single species c. achlyoides (Coker and Couch ) Coker is known to occur in Illinois . (1948a ) Beneke has reported the occurrence of this species froni Illinois . Genus : Dictvuchus Leitgeb • e • 0 • 18 6 8 : • • • , • • Bot 2 it , 2 6 : 5 3 Ju hrb w is s Bot 7 : 3 5 7 18 6 9 The genus Dict1us \·1as established to include a small <;_iroup of water molds in which the primary zoospore stage is completeJ y suppressed. In all species of .Pi_�tyuchus, the primary zoosporcs encyst within the zoosporangium (Figs . 169 , 170). In some species the zoosporangial wall is persistent and the secondary zoospores emer0e ·through the wa ll of the zoosporangium leaving behind a network of empty cysts. Such isolates are said to form 11true net11 zoosporangia. In such isolates the zoosporangia tend to be deciduous and frequently break away from the subtending hyphae to float free in the water . In other species the zoosporangial wall disappears, although the encysted primary zoospores cling together and retain the shape of the zoosporangia. In such isolates the secondary zoospores emerge , leaving behind a network of empty cysts in the form of a "false-net" zoosporangium, one without a zoosporangial wa ll. In a few species of Dictvuct1us , the primary zoosporangia are ah.Jays 2chlyoid and thereafter 61 . e typ ical dictyoid zoosporangia are formed All sp cies of Qt_ct�us form 009onia with a s ingle eccentric oospore ; antheridia may or may not be present ( F igs . 172 , 176) . The principl e means for identifying the species of Dictvuchus l1ave been on the basis of (1) the type of cyst-wall net left behind after the emergence of the secondary zoospores and (2) whether ach1yoid zoospore discharge occurred norma lly or could be induced (see Couch , 19 31) . The validity of making species determinations on these bases has become suspect since the discovery by Johnson ( 1951) of nn intermediate species , later identified as Dictvud� dodictvon (Johnson, Ziegler , and Linthicum, 1951), connecting false-net and true-net soccies. Subsequently, Padgett and Seymour ( 1974 ) have demonstrated that the type of zoosporanqial discharge in a particular species of DictyuchuG is quite variable and , therefore , species de lj mitation based on this characteristic is no t reliable. By using the zoosporangial stage for generic determinat ion , the following key, based on the oogonial and antheridial structures, may be utilized for species identification. Key to the Illinois Species of Dictxu�b_us 1. Thallus dioecious , antheridial branches formed diclinously from the ma le tha llus (Fig. 171) ••••D. monosE,oru_:_;_ , p. 62 1. Thallus monoecious , antheridial branches diclinous , androgynous or entirely absent • • • • • • • • . . . . 2 2. Antheridial branches entirely absent • ...... 3 2. Antheridial branches diclinous or androgynous •••••4 6?. 3. Oogonia with a neck-like protuberance at the base , oogonial stalks attached to the oogonium by a bcak-J.ike procc :; s ( i;" ig . 179 ) • ...... D. missour�:�ns i�, p. 63 the 3. Oogonia lacking a neck-like protuberance at the base, oogonial stalks not attached to the oogonium by a beak-like oroccss (Fiq. 174 ) ••. . - . . 4. Oogonia distinctly papillate ••••D. ES.l!lyojc.���' p. 61 4. Oogonia smooth-wa l led • ...... • 5 5. Anther id ia l branches mo stly androgynous, rarely branched and not engulfing the oogonium (Fig. 183 ) .•...... • • • • • • • • • • • • • • • D. ps eudo?chlvoides , p .. 64 5. Antheridial branches va riable , profusely branched , tending to engulf the oogonium (Figs . 185, 186 ) • • • • • • • • . . . ...... E4 Dictyuchus _!!1_ Jahrb. wiss. Bot ., l= 357. 1869. (Figs. 169-172 ) Dictyu chus !llO DC? E_Porus is, at present , the only dioecious member of the genus Dictvuchus_ and may be recognized by the terminal, spherical , unpitted oogonia containing a single eccentric oospore borne on short or long stalks , and by the one to three (occasionally more) antheridial branches formed diclinously from the male thallus (Figs . 171, 172). Isolates of D. monosporus have been reported from Illinois by Beneke (1948a) and Overman (1970). 63 J. Elisha f'15.tch. Sci. Soc. , t16: 227. 1931 .. (Figs. 177-180) Among those species of Dictvuchus that lack antheridial branches , D. m.�.ssour.iensj_.:?._ may be distinguished by its abundant , usually spherical, unpitted oogonia borne on thin, lateral stalks, the oogonia ornamented with a neck-like protuberance at the base, with the oogonial stalk attached to the oogonium by a beak-like process (Figs. 179, 180). I3olates of D. missouriensis have been reported from Illinois by Beneke (1948a). Isolates used in this photomicrographic study did exhibit the crooked oogonial stalk at the base of the oogonium and the beak-like process by which the stalk is attached to the oogonium; however , these characteristic oogonia occurred only rarely, with most of the other oogonia resembling those produced by isolates of D. anomalus Nagai. Dictyuchus anomalus Nagai J. Fae. Agr. Hokkaido Univ. , 32: 28. 1931. (Figs. 173-176 ) Isolates of D. anomalu� may be recognized by the spherical, smooth-walled, unpitted oogonia containing a single eccentric oospore and borne on thin, generally curved oogonial stalks , and by the absence of antheridial branches (Figs . 173, 174). Isolates of D. anomalus have not been previously reported from Illinois. Beneke (1948a ) recoanized_, -D. anomalus as a synonym of D. Tn onosporus . 64 Dictvuci1u� _a chb� 3. Eli!.>ha ..; iitc:1. Sci • .Soc. , 42: 218. 1927. Isolates of Q_. ��-l]l_ :!o id_�s may be recognized by thej_r achlyoid zoospore discharge from the pri�ary zoosporangia , fol lowed by dictyoid zoospore discharge from secondary zoosporansia , by the abundant , spherical, unpitted , papillate oogonia containing a single eccentric oospore , and borne singly on long , curved stalks , and by the mostly androgynous antheridial branches . Isolates of D. ac;_0lyoides have been reported from Illino is by Beneke (1948a). Isolates of D. achlvoides were not found dul.�ing the course of this investigation. D�c ;:tyu c1�u0. pseudoachlvo:Lde � Beneke J. El isha Mitch. Sci. Soc., 6'1 : 263. 1948. (Figs . 181-184 ) Isolates of D. P..:<:>eudoachlvoides may be distinguished by the occurrence of achlyoid and dictyoid zoospore discharge , by their abundant , spherical , unpitted oogonia containing a single eccentric oospore and borne on long straight or curved stalks , and by their androgynous antheridial branches . Previous reports of the occurrence of D. ps eudoachlyo ides from Illinois were by Beneke (1948a). pi ctyuchus oseudodictvon Coker and Braxton J. Elisha !-':itch . Sci. Soc. , 4� : 228. 19 31. (Figs . ".l.85-188 ) Isolates of D. ps eudodictyo n may be distinguished by thcj_r abundant , spherical, lateral oogonia pitted under the attached 65 anlheridial cells and born0 on curved or bent stall�8 , and by tl�eir pro-tuse ly bra!'lchcd, contorted androgynous or dic1inou.;:; anthcridiaJ branches . I::;olates of D. nseu9g_�i ct:.Y_C?J�. have produced all three types of zoosporangial discharge--true-net , false-net , and achlyoid--which renders species separation occurrence based on this attribute �uestionoble . The of D. PS�1:Jc1odj.�t v9:1 from Illinois has been reported by Deneke ( 1948a ) . _ Genus : _Drevi______leonia_.... _ _ _ Coker and Couch • , c• "h 11 . • • __LI._ .:212 . 1927. J • E 1 lS. 1_a r'•J. ·'-1... c n .::>C l. S OC. , 2 : 'r he genus !3_!'." evj J.ecmia. wa!"i er3tablishcd to include those _ water mold� with thraustothecoid zoospore discharge and oogonia containing a single oospore (Figs . 193, 201). In isolates of Drevilegn ia the primary zoospores encyst in one to several rov1s within the clavate to cylindrical zoosporangia and are liberated by the dissolution of the zoosporangial wall ; the primary zoospore cysts separate and drift away singly or in small clumps . The mycelium of Brevilegn ia is said to be depauperate, since it is of limited growth and of dense and opaque appearance. That the oogonia contain a single oospore readily distinguishes isolates of Brevileania from those of Thraustotheca . It is apparent from the studies by Salvin (1942 ), Rossy- Valderrama (1956), and Ziegler (1958) that in many isolates of Brevi leania the asexual characteristics are extremely variable. In some isolates zoospore discharge may be 66 thraustothecoid, dictyoid, and achlyoid on the same thallus . It has been pro�osed that a ll species �nd varieties of Brevilconia be relegated to two species , and that the genus be reduced to a sub-genus of Thraustotheca with the species .?.E��v5].e described a new species of _g_�ia , one with typical and very stable asexual features , and , hence , opposes any revision of the genus. The taz:onomy of Dr: ev ilec:nia remains in a state of chaos pending further study on species variability. Key to the Illi�o is Species of Brevileani� 1. Zoospor6ngia of two types , the primary zoosporangia achlyoid (Figs . 189 , 190) • • • • B. bispo r� , p. 67 1. Zoosporangia never achlyoid • ...... • • • 0 2. Oogonial wall irregular or distinctly papillate • 3 2. Oogonial wall smooth • • • ...... • • . • • • . • 4 3. Antheridial branches generally absent , or , when present , diclinous (Fig. 193 ) . . . . . B. diclina , p. 67 3. Antheridial branches mo stly androgynous (Fig. 19 7) •• . . . ...... - ...... B. unisperma , p. 67 4. Oogonia relatively large ; antheridial branches absent or, when present, androgynous • • • B. megas�1a , p. 68 4. Oogonia relatively small ; antheridial branches mo stly androgynous (Fig. 202 ) •••B. subclavata , p. 68 67 · o c ------Brevile0··· .. -nia-- -·---hisporR C u h J. Elisha Vii tch . Sci. Soc. , �2: ?.28. 1927. (F'igs . 189-192 ) Isolates of B. bisoora may be readily distinguished by their a chlyo id zoospore dischnrge from the prim�ry zoosporangia by thraustothecoid follo�ed discharge from secondary zoosporangia ( c Figs . 189, 190), by their abundant , small , spheri a l , smooth- walled oogonia borne singly on long slender stalks , and by the androgynous antheridial branches (Figs . 19 1, 192 ). This is the first report of 2� bisp_ora from Il lir!ois . Brevilecnia diclina Harvey J. Elisha Mitch. Sci. Soc. , 42: 243. 1927. ( Figs. 193-196 ) Isolates o� 9. §i clina may be read ily distinguished by their abundant , spherical , papillate oogonia borne singl y on lateral stalks , and by the usual absence of antheridia l branches , 196). or , when present , diclinous (Figs . 19 3, Isol a tes of B. diclina have been reported from Illinois by Beneke (19480 ) Brevileqnia uni�rma. Coker and Braxton J. Elisha �itch . Sci. Soc. , �2 : 213. 1927. ( Figs . 197-200) Among those isolates of �r evileqn ia with ornament ed oogonia , B. unisperma may be recognized by their abundant spherical to oval oogonia borne on long slender stalks , and by the androgynous antheridial branches (Figs . 19 7, 199 , 200). 68 e Isolates o= B. �_!'.!-�SJ2.er.ma hav been reported :from Illinois by Beneke (1948a). Beneke also identified three varieties of D. uni_�J2:�rm� (var . m�J_:� ' var . _c:ie�Jc� , ri nd var •.�J_t:.� .��li?.) that dif f erect from �-· .'!Ei spe��_?. var . unisperma by the absence of antheridiR l branches Dnd by the oogonial shape and branching of the oogon ia l stalks . Isol ates of the three v ariet ies of Brcvileania yn isnermD were not found during the course of this investigation. Brevilennia meaasperma Harvey 5 : J • E 1 is ha l'!i itch • $ c i . Soc • , 4 3 2 2 • '193 0 • Isolates of D. !'.!_£_gasperm� may be distinguished by their abundant , spherical to elongate oogonia borne on long l ateral stalks , and by tl1c g enera l absence of the antheridial branches , which when present , are hypogynous. The occurrence of B. megaspe rma from Illinois was reported by �enekc (1948a). Isolates of B. meaaspe rma were not found during the course of this investigation. Brevileania subclavata Couch J. Elisha Mitch. Sci. Soc. , 42 : 229. 192 7. (Figs . 201-204 ) a r Isolates of s. subclav t a may be ecognized by their abundant oogonia containing a single eccentric oospore , and borne on long slender stalks , and by the androgynous antheridial branches (Figs . 202, 204 ). I sola te s of B. subc lavata have been reported from Illinois by Beneke (1948a). 69 Genus : ---·�Geoleonia_.,..:___ _ Coker J. E l isha Mitch. Sci . Soc. , 41: 1530 1925. (Figs . 205-208) ':i.'he genus Geo} _eol':!_�� was estoblish2d to include a small group of water molds in which the primary zoospores encyst in a single row within the zoosporangium, and germinate without a secondary mo tile stac,c. The zoospores are thick- 2 e e walled and very 1 rg when compar d to the diameter of the zoosporangium; this often results in a regular and conspicuous bulging of the zoosporangial wall (Fig. 205). After the decay of the zoosporangi.al wa ll , the zoospores are liberated and germinate by the direct formation of germ tubes (Fig. 206). Isolates of G� oleania form a mycelium of very limited growth, result ing in a depauperate , dense, opaque colony. The oogonia e of G o le� are smooth-walled, unpitted, borne s ingly , and contain a single eccentric oospore. Each oogonium has from one to four androgynous antheridial branches arising from just below the oogonium (Figs . 207, 208). The only species of Geoleonia known to occur in Illinois is G. inf lata Coker and Harvey. Beneke (1948a ) has previously reported the occurrence of G. infl2ta from Illinois . 70 Figures 1-8 Fig. 1. 1 ions is sa de Bary. Zoosporangiun: !).'U_ s:YE'O . before zoospore cleavase. 550X . 1.:ote that the terminal has di-fferentinted a-· 0 rnma into an oogoniurn containing a sinale oosp�ere . 650X . Fig . 3. Pyth:i_._p....E_si�� ..YE1o sa de Eary. Gemma containing zoospores. 550X. Fig. 4. Pyl: hi.�ps is_ �..Y.l]_'!.?_�.9- de Bary . Immature oogonium with a few blunt outgrowths and with a single androgynous ant�eridium. 1000X. Fig . 5. -�t_h_�.2..P� is _ -�ymosa de Sary. Oogonium with blunt e papill a t ions and a s ingl attached androgynous antheridium. 900X . Fig . 6. Pyt h i���i s SY_m� de Bary. Oogoni um containing a s ingl e oospherc . 900X. Fig . 7. _?vt hiops is s;..,Y!!1o sa de Bc.ry. Oogonium \·Ii th a single subeccentric oospore. 1000X. Fig . 8. P::{��:. droplets on one side of tr.e oospore. 12COX . 72 Fi9ures 9-16 papillate oogonium. ?COX. Fig. 10. S22so l�nia _a ste�C?.J?hgra_ de Bary. Papillate oogonium with androgynous antheridial branch. 35CX. oogonium with an oosphere. 750X. Fig . 12 . Saoroleonia �stei.:_o phor� de B2ry. Oogonium with subcentr ic oospore. 1150X. Fig. 13. Sapro l�_n=h_� su_btc:��_f-�ne� ( Dissmann ) Seymour . Habit showing terminal and lateral oogonia with androgynous and mon�clinous antheridial branches. 225X. Fig. 14 . ��prolecmi_a S\lbterranea ( Dissmann ) Seymour . Oogonium with two oospheres and attenda�t n androgy ous antheridium. 8COX. Fio. (Dissmann ) Seymour . ,J 15 . Sanroleonia..:..___ ·-�------subterranea Apicu late oogonium with a s ing le oosphere. 900X. Oogonium with subcentric oospore. 1050X. 74 Figur0s 17-24 i (Coker ) Sey- mour. F g . 17. �--Saoroleonia---4�--- __Gccentr�ca,,. ____ . _ _.___ Portion of a hypha showing oogonial arrangement . 550X. Fig. 18 . �or.oleqniD. eccentric a (Coker ) Seymour . t:m Catenulate ooqonia; terminc.� 1 oogoni \·Ji ti1 a single conspicuou::; pit . 1000X. Oogonium with an eccentric oospore. 1000X. Fig . 20. .S ap�o leg[1ia �s:.£.c=:ntr ica (CokGr ) Seymour. Oo gonium with an irregular oogonial wall. 1000X. Habit showing oogonial variations. 188X. 600X . Oogonium \vith hypogynous antheridial cel l . Fig. 23. �-c:Er ole__9!1}- a hypoqyn� (Pringsheir. 1) de Bary. Interca lary oogonium . 600X. Fig. 24. Saoroleania l"!.Y.QO OV� ( Pringsheim) de Bary. Terminal oogonium with centric oospores . 750X. @ 76 Figures 25-32 s howing oogonial arrangement . 'LSOX. Fia·' . Saoroleania turfosa (t;inden ) Gaumann. Immature 26. __...... -··�--L.·-·- -· ··-·.. --·- oogonium with thick , conspicuously pitted oogonial wall and short androgynous antheridial branches . 500X. • ;-, _ p � .1- ir·'= ,.. 27. _ e m � Fig. Sapro 1--� ·.:..:3-:_.<:: ...!:::..."?·- ,_ o.:.a ( Mind n) Gau ann. Oogo ium with centric oosporcs . 700X. Fig. 28. S aprol<::m:ii� �u rfosa (Minden) G;:,umann. Oogon ium containing numerous centric oospores . 600X. Fig. 29. Saprolegn2: a !:o_rl !lq ::�� de Bary. Gemma that has differentiated into a zoosporangium. Note zoospores. 125X. Fig . 30. Sapr�J eonia toruJ.osa de Gary. Catcnul ate oogonia with oospheres. AntheridiD absent . soox. Fig. 31. �rol�n ia toru_l o�-� de Bary. Habit shm·ling oogonia. Note the formation of an oogonium inside a discharged zoosporangiurn. 125X. Fig. 32. Saprolegn ia �o rulosa de 3ary. Oogonium with a s ingle centric oospore. 1000X. '1 8 Figi.l�CS 33-40 Fig. 33. Saproleqn�-� f��ax (G:::-uit:1. ) Thi.lret. 'I'errninal, pitteti oogonium with oo�p�cres . 750X. Fig. 34 • .S�l'.:'olc;:c;nia i'er2x ( Gruith . ) 'i'hur 0t . Oogoniurn with oospheres . 650X. Fig . Sanroleania Gru.i·ci1 .) Thuret. 35. -·--··-....------·---fer oogonium with monoclinous anti-::eridial branch . 550X. oogonium with centric oospores . 750X. renewal :)y internal Droliferation. 183X. diclinous anthcridial branches . 250.X . Ooo·' onium \vi th s clasping antheridial cel l . 750X. oogonium with subcent r ic oospores . SOOX. 80 Figures 41-48 e Fig. 111. S e oogonium with oospher s. SOOX . Saprol�qnia nm Terminal Pig. 43. -...---·------•--dicJ.ina Hu L hrey . with n 700X . oogonium ce tr ic oospores . with centric oospores and attached antheridial cells . ?COX. Fig . 45 . ��..?J.�_gn �a J.ito .?:? a l.i� Coker . Terminal , pitted oogonium with oosphere�. SOOX. oogoni al stalk with oogonial initial. 350X. Fig . 4 7. Saorolea�ia li ra i Coker. Terminal ___.._ __... ·---to ----l s a o oogonium with oo spheres ; ndrogyn us anthcridial branches . Antheridial cell l ap ical y attached. 7COX. S Fig . 48. aoro3=_�3J:?ia l:i'.:9rali_� Coker. Oogonium with centric oospore� . 700X. 82 Fiaures 49-�56 Fig. 49. S2oroleu�ia u�isnora ( Co� a Habit :fr:owir.g 0090:-i:La generally contain5..r..o single oosphere. 188X. F ig . 50. §.�.!?.E.?M.fEli a_ .'-��J..s?2�.r.:·� (Coker. and Conch ) Seymour. Oogor:ium with an irre0ul2r oogonial wall. 850X. vdt�1 600X. Pitted oogonii..:m a centric oospore. Oogonia containing su�centric oosporcs. 1100X. SaproJ.esnoid disc�arge. Note raoid e�ergencc t�rough the exit terminal pore . 4 5 0X . SanroJ conia Fig. 54. -·-..-·-�-J--.- Saprolegnoid ------rr:eaasoerma.... . Co1 discharge. Zoospores actively s11d.mming away from the zoosporangium. 450X. hypha showing two l a teral oogonia with their attendant mor:.oclinou� antl;cri.dia . Note the laterally attached anthcridial cells. 188X. Fig . 56. Saoroleania meqasperma Coker . Oogonium with a subcentric oospore . 950X. 34 Figures 57-G4 Fig . caud.LJ de Bary . An elong t 57. --:::,e:)to - leq:ria --- ·--·-ta a e undifferentiated zoospor�ngium with the prlraary zoospores formed in a s ingle row. 125X .. with coiling cU.cJ.inous anther idial 1'.)runches wrapping around the hypha and oogonial stalk. soox. contain ing a single oo�porc with small droplets enc ircli�g the �erip�cra l region . 800X. Fig. 60. Leptolcgn:l.:_� .s::_aud2ta de Bary . A thick-walled oosporc ., 800X. T.'.1:ig. . 61-· . Portion of a zoosporangium showing the elongate primary zoospores . SOOX. Fig. 62. Aphanomvs;e�_ l aevis_ de Bary. Encysted primary zoospores. Note slender por t io n o� the zoosporongium. 650X. Fig. 63. Aphanomvces laevis de Bary. Oogon� cont aining a s ingle oospore with a large central oil globul e . Antheridial branch monoclinous . 700X. Fig. 64 . Aphanom��es l��vi� de Dary. Oogonium with a single oospore . Note antheridial cell. 1250X. 8 C:v. Figure.::; 65-7?. c i des Fig . 65. ;.., Dhano11r:ces he--- i o-- von I :inden . Oogo 1 a _ __.___·--�-·- - 1 · -- r i V!ith coiling cmt�eridial br2nci·12s. 650Xo with coiling ant�!c;:i.dial brc::ncncs wraµping about the hyph ac and oogonial stalks . 650X. with a �inglc oospore with a large central oil gJ obule. Iiote the irregular OO?Onial wa ll due to 0radu2l disintearation of. the ··' - t1·1e antheridial cell s . 600X. Fig. 68. Aohanomvces helicoidcs von inde . Mu.ture _ ....____ -�------·------E n oospore . 650X. Fig . 69. !'..£.:- 1:!.a.n_q�yces steJ.} atus de Bary. Ooqoniur.1 with nur.:erous bluntly conical tul.Jercles . Androgynous antheridial branch. 800X. containing a single oosphere and showing the c c blunt oni al tubercles . 700X. Oo c_,o n ia with oogonia l wa ll ornamentation. 700X. Fig. 72 . _!.\E_ha_IJ.2_m�e � stella::us cie Dary. Oogonium with a mature oospore wit� a central oil globule. 700X. 83 Figures 73-80 • . - _ r� . o Fi�1 73. J\c!"_l.Y� � wallc�d oogonium \·Jitl1 a s ing l e oosphere. :·lote the lack. of �n th(�r idj.al branches . 1000X. l:' • - ig. 74 . Oogon:Lt�m with papil late ornamentatio�s . 450X. monoclinous and dicl inous entheridi�l branc�es . 213X. AchJ.va Fig . 76 . ____.... _ .car ..._. .. .. ______olinic:rna.. __ _ Col:er . Mcture eccentric oo::::porc. 1000X. i" Cl ..::> 1 3 i Fig. 77. Achlva raceDosa Hildebr�nd. t.: l " t · \... . ·-...-_.e'\- _ __ _...... _ - -- - :O\•Jln<; lateral oogonia containin9 oospJ·: cre.:; and attendant androgynous a::.theridia . 225X. Fig. 78 . Achlva ra c r.'os a Pildebrand. ------e Imrr.ature w oogonium i th c;:i9ynous antr:e!:'idia. 313X. Fig . 79. Achlva racemosa Hildebrand. Oogonium with -�-·- . - \·J oos9hcres . Note that the oogo;-1ie::l a l 1 is pitted under the attached antheridial cel l. ssox. Achl-� e Fig. 80. racemosa Eildebrand. La t ra l oogonium with centric oospores . 550X. 9() F' i�; ures 81-88 e C h·!o oospherc:J and a once -coil d oo !onia l stalk. 450X. Fi<] . 82. :J; chJ.:.:.1c=1•• �c; -�).:.�--a de Bary . Apiculate 1 ooaonium v.r ith t: ree oosphcrcs . 450X. "' . .i.' 83. ig. Non--ao.:i.cu1 ate oogonium with monoclinous antheridia . S00X. i? ig . 84 . /\ch1=_:��- -�t?iculat_?._ de Bary. Subccntric oo;:;pore. 1000X. Fig. Achl \"u uol vc:ndra Hildebrand. yriform t� S. "'---·---- P oogonium containing oosphere s not filling the oogonium. Note the much-branched androgynous anti1eridial brc:inches . 300X. 86. Fig . Achlya po lyandra Hildebrand. Oogonium with c a its mucJ-1-brc:inched c:ttendant ant:h r idi . 450X. Fig. 8 7. Ad11y_ � po l v�.:_:lF.!� Hildebrand . Oogonium with attendant androgynous antheridia . 450X . Fig. 88. Hildebrand. i-;aturc -A--Achlva polvan -----��-dra subcentric oospores . 750X. 92 Fiqt!rc-� 89-96 _ vei n g . Aci·:J_,. _._ o o Coker 2nd Couch . ogonia Fi 89. __ ·-----ri O · :Y \vi ti1 attenda t n:onoclinous antr�eridia . 300X. Fig . 90. J\c}J_�.:X�� 9_'.fio� Col:er and Couch. Oogonium with <.: fe\·/ oosp:1erc�s borne on curved stalk:. ;·�o te a that the ooryoni l \·Jall is pitted under t;1e attached antl�cridial ceJ 1. 500X. Fig. 9'1. 8-C:lJ.l'f_�. 9_ri o� Col�cr and Couch. Oogonium with s . oo sphere Note pit under point of attached antheridial cell and fertilization tu::>c. 500X. a v. F'ig. 9?. A<;:_l]l:_ya orion C:oker and Couch . Oo oni m e e cont a ining mature cc ntric oospores. 500X. Fig. 93. J:..chlva americana Hurr:phrey . Lateral oogonium with mo noclinous antheridial branches c:irising near the stalk. �63X. Fig. 94 . J\ chl va am�ricana Hwnphrey. Conspicuous l './ pitted oogonium \•J ith oosp:-ieres and rr.onoclinous antheridia . ASOX. rn Fig. 95. !-c hl ya r.:me��-�_?na Humphrey. Oogoniu with attendnnt antheridium; antheridial cell attached by projections. 700X. numerous small , eccentric oospores. SOOX. · Figu r-es 97-104 \·Ji-th a monocli�OU3 cnther:Ld ium . SOOX. with j_ ls attendant and.i:-ogynous antheridium. ?75X. um Fig. 99. Ach�.-�.�� .S:!�;.spi�U..?_ Coker . Oogoni V!ith mature eccentric 003porcs . note t!1e aborted c oos pher : . 700X. pj g. 100. 1'�hlya f9IL-:>nic11C1_ Coker . Oogonirn:i with oospheres and antheridial cell &ttached by projections. 1:ote fertilization tube (1\) . 900X. v Fig. 10 1. �2-.�b-�E- 5-iu�_i_� Cok<:?r . Acl:l o id discharg<� fro� secondary zoosporanqium. 213X . Fig. 102 . £'.c hlv� du}) i�- Coker . 'l'h raustoti·1ecoid discharge from primary zoosporangium. 450X. Pig . 103. Ac� ?�h i?_ Co1:::'2r . Lateral pi 7-ted ooqo:-iiurn with dicl inous antheridial branches. 213X. Fig . 104 . Ac1']lYE. �ubi2 Coker. Oogonium with mature eccentric oospores. 850X. 96 Figure�; '.i. 05-'l "J.2 a lateral and terminal oogoni containing mature eccentric oospore� . 175X. coiling diclinous antheridial branches . 163Xo Fig. 107. Ach lva oroliferoides Coker . Oogonium with some mature oospores and a few aborting oospheres. Note the coiling antheridial branches . 450X. pitted walls and containing eccentric oospores . SOOX. showing a terminal oogonium and a spherical hyphal swelling. 250X. Fig. 110 . J £�ff\.l:.:_�i! (Harvey) Johnson. Portion of a hypha showing lateral immature oogonia and diclinous antheridial branches . 163X. Fig. 111. _!l.c hJ�ra di_:ffusc: (Harvey) Johnson. Oogoniurn containing eccentric oospores , a few have aborted. Note that the oospores do not fill the oogonium, and that the oogonial is pitted . 600X. Fig. 112. �.c_hJ._ya 9_�i._%_l;lS 2 (Harvey) Johnson. Gem:na that as has functioned a zoosporengium. SSOX. 98 F i�!ur0s 1.13--"'.1.20 ______.. _ _ - - 1"13 ., vu - Fie._, l\chl - Oo<::onium :f1<.-:c�';.� llt:·t.:::. Coker. witil --·--- ··-· -- oospheres and attendant dicJ inous c:mtl;cridia . soox. Note that the oosphcres do not fil l the oogordum. GOOX. _ _: ___ ;...... :...� . � . 11 5. - ._ Ach] v -::i : . . :ature eccentric Fig. --:laoel� - ::_ 1 :::.. J- � I . --· :_� _: �... oospor2s . 650X. Fi g l\ chl :f lacellata Coker. Eccentric oospore. . 116. ---�--ya ··- --�----..... --- Note the absence of ot�er oosoheres that failed to mature . BOOX. Pig . Achlva e ia Pieters . Oogonium 117. __...... ,_ kl ------bs na with oospheres and dicl inous antheridial �ranch. 450X. Fig. 118. Ac�l)'-� k�<:>P..:'."!_:!-_a__:�� Pieters. Monoclinous antheridial branch arising from a point remote from the- oogonium. - 188X. - Fig. Achlva klebs-iana Pieters . Oogonia 119. ----� - v-:ith ·· - ··· mature oospor- es . 450X. - Fig. Pieters . Oogonio. \-.1 ith 120. /�chl_Y._".!_ l�J.0bsi_?.!:.?.. mature eccentric oospores . Note that the oosoores fill the oogonia a nd th2t the oogonial wall is p itted only under the attached antheridial cells . 450X. 100 i� 'igures 1?·.J.-128 papill atc oogonium with a s ingle androgynous antheridium. 475X. Fig. 122 . Achl v� col�£_a t:a Pring�;heim. Oogonium 1:1 i th centric oospores . 650X. Fig. 123. Achl Y_� Fringshcim. Oogonium with :. _s:pl_s;rata. centric oospores and androgynous antheridium. 500X. e O ni with Fig . 124 . Ach J. ya colorat� Pringsh im. ogo um exigynous antheridia . SOOX. Fig . 125 . Achlva mphr . Terminal , --- �-p a oillo- --s a Hu ey densely papill a te oogonium with an apiculus. 450X. F' ig. 126. l\chly_� p�illosa Humphrey. Smooth-walled , terminal oogonium with its attendant monocl inous antheridia . 375X. Fig. 127. Achl va J2.9t)il lo�� I-J umphrey. A sparsely papillate, int ercalary oogonium with monoclinous antheridium. 225X. Fig . 128. Achly_c:_ p_�illosa Humphrey. Unpitted oogonium with centric oospores . 500X. 102 Figure:') 129-· 136 . - I., ig. ...; ? 9 _ . Immature oogonium with marrmiform ornamentation3 and attendant androgynous anther idium. 650X. single oosphere and short antheridial branche::;. soox. Fig . 131. �chlya F.:lqJo;�E. Maurizio . 'l'\·Jo lateral ooqonia. 288X. Pig. 1. 32. r'\ cr�� radiosc:i_ Viaurizio . J\1a ture subcentric oospore. 700X. Terminal , papillate oogonium with a short monoclinous antheridial branch. 225X. Fig. 134 . Achlya treleuseana (Humphrey ) Kauffman. Pitted oogonium with oosphcres. SOOX. Fig. 135 . AcJ:.�ya tre_lec:iseann ( �lumphrey) Kauffman. Intercalary oogonium with oospheres . SOOX. Fig . 136 . i\ chl� j:releas0a� (Humphrey) Kauffman. Mature subcentric oospore . 600X. J.04 Figures 13 7-·144 Fig . 13 7. 1"\\j1�ya !"C��ur·:_n: Cornu. Immature oogonium with truncate ornamentations . 600X. /� cill rc�curvd Fig. 138. --�-va Cornu. Oogonium with oospheres . ssox. Fig . 139 . Achlva recurva Cornu. Oogonium with eccentric oospores and attendant a ntheridi2 . 550X. r Fig . 140 . :..t\c_:! ly _':;l_ _f_E]_C:_l!FY� Co nu . Lateral oogonium containing eccentric oospores. Note truncate ornamentations . 550X. e F'ig. 14 1. Ac;_!i l_ y_ ?_ S:E(':l.}_l!].._?t� Z i gl er . Achlyoid discharge and zoosporangial renewa l by basipetalous succession. 250X. Fig . 142. Ach1-_�. -�.i;:-ci::_i�1lat� Ziegler. Ornamented oogonium with a s ingle eccentric oospore. 850X. . • _ _en . F.ig. 143 A_ '1)' a_ crenu .:..J �-: t- a "//..,ieg' 1 er . Terminal oogonium with papillate oogonial walls. 850X. Fig. 144 . Achlva _s:_E_ei:i_u __l a_t a Ziegler . Oogonium with papillate to tuberculate ornamentations . 950X. 106 F'ig1lre� 145-1.52 ·J.!15. Fig. Protg ac:l-::_�_y_� .:_:_y_I?..S? .2...'! .}]..C)_ Shanor and Conover . Zoosporangial discharge . Note that the zoospores have emerged from the exit pore and have encysted away from the hyphal tip. 175X. Fig. 14 6. i��ot0:_�h�L� .'b..ypoqyna Shanor c.nd Conover . Achlyoid discharge , zoospores encysting in a cl uster at the exit po re. Zoosporangial renewal by cymose branching. 113X. Fig. 14 7. �F...?_t_o 2ch_ly.?._ b_.YJ.29-9.Yrl� .S hanor and Conover. Zoosporangial renewal by internal proliferation. 188X. Fig. 1.48. _?ro toachl_ya_ .b�t.2..'.:')qV0_�. Shanor and Conover. Papillate oogonium with hypogynous antheridial cel l. SSOX. Fig. 149 . Protoachl v2 hypo C':..Y_na Shanor and Conover . Terminal, oogonium with two oospores . SSOX. Fig. 150. Protoachlya �oogyna Shanor and Conover. Papillate oogonium with monoclinous antheridium. ssox. Fig. 151. Protoachlva hyp�_yn a Shanor and Conover. Intercalary, unpitted oogonium with a single oosphere and monoclinous antheridium. SSOX. Fig. 152. Protoa�h�_y_� �yp�qv�� Shanor and Conover. Oogonium with centric oospores. 550X . 108 Figures 1S3-160 F'i .g . 15 3. LP]._0._:!es ar_-:_drgc.;ynus (Ace her ) I-!umpl:rey . Apl anoid discharqe. Note th at the zoospores have e ncysted inside t�e zoosporangium and have germinated by gerr"ll tu!.Jes thr.ougl1 the zoosporangial wa ll. 200X. Intercalary oogoniurn with oospheres and attendant monoclinous antheridiurn. J.88X. Fig. 1. 55. 1\ ol anes a0droq"nUE_ ( J\ rcher ) Humphrey. Intercalary oogonium with oospheres . Note the conspicuous pits in the oogonial wall. 450X. h u Fig. 156.. Apl an_§?s androqvnus ( i\rc er ) H mph rey. Mature subcentric oospores. 450X. ig 7. Thraustotheca clavata F . 15 ------·------·· (de Barv.... ) Humph.. rey. Thraustothecoid discha rge . Note that the zoospores ar e liberated by t he dissolution of the zoosporangial wall. 188X. av Fig. 158. ThEau�>totf:eca E l ata_ (de Bary ) Humpr1rey . Pr imary zoospores germinating wit hout a swimming stage. 188X. Fig . 159. Thraustotheca clavata (de Bary ) Humphrey. Oogonium with oospheres and diclinous antheridia . 550X. Fig. 160. Thraustotr,eca cJ.avat2 (de Bary) Humphrey. Mature eccentric oospores . 550X. 110 Figure:; 161-168 Fig. 161. :l, hr�-1:2.�?��2.!J.:i ecr.l Pf i��-CJ..!}va Coker and Couch . First formed zoosporangium showing achlyo id dischur�e . 375X . F i g . 162. TJ.1ro_}l$ tO_thec<.:_ EEJ.:.!t:!DECh�-'�� Coker and Couch . ThraustotJ·: ccoj d zoospoi.-angium. 213X. Fig .. 163. �l,hrau?tg_!:he._s:a_ P.£�-�C2 .C1_�h�ya Coker and Couch . Immature ooqonium \:1ith dense popillciti.ons 2nd attendant mo noclinous antheridiurn . SOOX . Fig. 164 . 1' hrau�totheca .E.:.��rnoachlj@_ Cok0r and Couch . Oogonia with mature eccentric oospores . SSOX. Fig. 165 . fa a ( Cok:or Couch Co1cer . 1yp 'l:..£. �eqn�E_ ES_i_)__l_yo:� d�;-� & ) Zoosporangium with the zoosporcs being l iberated by the breaki n9 off o:: the terrninol port ion of the zoosporangium. Note the remnant of the apicnl ca p (C ). 600X. v u Fig. 166. Cal ptra l e�L u c!�.:.YS>ides_ (Coker & Couch ) Coker . Oogoniurn with a once-coiled oogonial stalk and attendant mo noclinous anthcridiurn. 275X . Fig. 167. _s:a�;Q?traleqn�_ ?_ �c_i2_�Y.9_��e z (Coker Z: Couch ) Coker. Oogoniurn with oosphere and a single oogonial wall pap i l l at ion. SSOX. Fig. 168. Calvotr_?l eonia _?chl..YQ-ides (Co��er & Couch ) Coker. Oogonium with a single subcentric oos9ore. 600X. 112 Fiaures·' '1 69-176 169. Fig. --Dictvuchu: ·-- ·------> .mono ...-----�--· soorus ·� Leitne-� b . Dictyoid �oosporangiurn. Note th'3t the zoospores have encysted inside the zoosporanqium and the network: of empty cysts left behind by e r the mc 9ing zoos pores . 950X. of a secondary zoospor e from the terminal zoosporangium (B) . Note that the secondary zoospores from previous liberations have encysted just out side the zoosporangium. soox. Fig. 171 . Dic�vuch�s. !_00_n o�_p9r��� Leitgeb. Oogonium with eccentric oospores and attendant diclinous antheridium. 650X. Fig. 172 . Dictvuchus mono..E_�� �- Leitgob. Oogonium containing a single eccentric oospore. SOOX. oogonium with a single oosphere. 263X. Fig. 174 . �-i cty}lchus _an_o_m alu� Nagai. Unp itted oogoniuin with oosphere . 650X. curved oogonial stalk and conta ining a sing le oosphere, Antheridia absent . 600X. Fig . 176 . pi ctv\}c hu� �n9 malus Nagai. Viature eccentric oospore. 600X . Fig. 177. missouri e�sis Couch. �Iabit- s'hov1ing lateral i�nature oogonio . 138X. Couch . Oogonium \·Jith 178. ------·missouriensis· . -- '4-... ._• • oosphere . 550X. s eccentric oospore. l'fote that the talk is crooked at the base of t�e oogonium. ?SOX. oosphcre and showing characteristic attachment of oogonium to ooqoniul stalk. 750��. with a single oosphere o.nd attendant andro gynous antheridiura. Note that the anther idi a l branches profusel branched. are not y SSOX. vu Fig . 182. Dict chus �eudoachlyoides Beneke. Immature oogonium with attendant androgynous antheridium. ssox. Fig. 183 . Dictvuchus Es eudoachlvoides Beneke . Oogoni.um with a s ing l e androgynous antheridium. 450X. Fig. 184 . Dictvucb�E 12s eudoacr:lyo i de s Beneke . r-'!a ture eccentric oospor.e?> . 550X. 116 F :Lgurc�:::; 1.85- 19 2 Fig . ')�>cnidodict·'/on Col-:er ar.d 185 . _Dictv_ __. __...... _ ucriu.::______.. ______. --· ·---··- Era:;{ton. · c. en Oogonium i.:i.-Ch tt dant a.ndro-;;ynow; llnthe.L-idiu. Note the profusely branched antheridiDl branc�cs engulfing the oogonitw . 238X. OogoniG with profusely braDched antheridial a Oogonium containing single oospherc. Note that the antheridial cells are attached by pro jections. 750X o Eature eccentric oospore. 750X. Fig. 189 .. Brevileonia bisoora Couch . First formed ------·--"--·------··· - zoo sporangium exhibiting achlyoid discharge .. 225X. zoosporangiurn exhibiting thraustothecoid discharge. 700X . with attendant androgynous antheridium. 600X. Fig . 192 .. Breyil_eCT_: _��a b��-p_or.�. Couch. Hature eccentric oospores. 700X. 'l 'i8 _ Fig . 19 3 . ---·I3rev:;· lc;nnia diclir12·- r; c..r'1ey . -- -· - .. - -· - orna;nenta t 5.or:.� znd c;ttcr:dun l: d:i.ci ::.no-..is an t:wr idia . 600X. Fig . Brevi di ar . Oo o a le0nia__,,.._._ ---- -·-· . 191 . ------�--.-... cl inc:i i : vey q ni that the immature ooaonium is snooth-wa lled \·1 ith w!1ereas the ooocmium ti'l.e oosphcrE� has an irregul ar wall. 750X. Oo<;_ronium \·J ith Fig. 195. -Brevileonia·------diclina Harvev.- mature eccentr ic oospore. 1000X . O Fig. 196. Drevileonia----�- - ---�·-diclina --- ilar ey . o o i m --- v g n u \·J i th irreoular wa l l and eccentric oo spore . 1000X. Coker and Fig. 197. --Brcvil--·-·-eonia unisoerma ---�-·- Braxton. Immature oogonium with µrofu s ely branched androgynous antheridial branches . SOOX. Fig . 198. nrcvileonia Co er and Braxton. -----·---k-- ____unis... nerma_, -- ·---- k Oogonium with branched antheridia. BOOX. • J..' a� Oogoniun wi�n irregular to papillate oogonial wall and eccentric oospore . 800X. : Fig. 200. Brevilecmia unisnern a Coker G�1d Braxton. \vi·:::h r Oogonium an irregula oogonial wa l l and a s ing le eccentric oospore. aoox. 120 Figures 20".1.·· 203 ?ig . 201 . BreviJ !':u')clr.iv�1ta Coucn . Zoo::>porangiuin --·---ecr.ia·-··--- __.. _. - -·--·· of the thraustot�ecoid type . 550X. oogor1ium �·.?iti1 attendant andro�'.n.; o'.l:> t:mtl:eridia. 800X . attached 2ndrogynous ar.thcridia. 800:A.. Fig. Brevilc0ni� subcJ.avata Couch . Sr;iooth-wa lled 204. ----·-· - --..�.... ------··-·---··- - oogonium with a mature eccentric oospore. 800X. e e Fig . 2 0 5 . 0 o l o_n i� in_:fJ.p_tC:. Coker and Harvey. Zoosporangium with zoospores formed in a single row. Hote that the zoospore::; have caused the zoosporangial wall to bulge . 375X. 6 e Fig. 20 . Geo� 0nia .?--n f�J:.a. Coker and Harvey . Zoospores have encysted inside tl1e zoosporangium to be liberated by the dissolution of the zoosporangial wa ll. 475X. Fig . 20 7. .?e oleonia_ inf �-�-t_?_ Col:er and Harvey. Oogonivrn with an eccentric oospore and androgynous anther5.dium. 1. 150X. Fig. 208. Geoleqn ia i;if lata Coker and Harvey. Oogonium containing a mature eccentric oosnore. 1150X. LITE�hTURE CITED Benel:e , E . S. 19�8a. i, rr.o;io9ra9r.ic study of Illinoi3 species of the S01::n·oJ.cc;Fliales and !_cptomite:' J. �s . Doctoral dissertatio� : Univ. of Illinois , Cha��2ign . ------. 1948b. ..; 11(�i·J species of !.�c;.I�l� and of D�_s:t,;uchi.1�.· J. Elish2 Ni�ch . Sci. Soc. 64 : 261- � 65 . •.:; Bretsnyd�'r , E . 1943 . A study of tl:c occurrence and distribution o� aquatic Phyconycctes in Cry� tal �ake . �as�er '� thcn is : Univ. of IlJ.inois , Champaign . Cejp, K. 1959 . Flora CSR . Oomycetes I. Naklad. Ceskoslovcnske 2kad. ved , Pi ahe . Coker , C. 1923. 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