EPA- 905378003
United
Environmental Protection Agency
Region V
Central Regional Laboratory
536 South Clark Street
Chicago, Illinois 60605
October 1977
AN ILLUSTRATED KEY
TO THE PLANKTON 1C ROTIFERS
OF THE LAURENTIAN GREAT LAKES
Do not WEED. This document
should be retained in the EPA
Region 5 Library Collection.
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AN ILLUSTRATED KEY
TO THE PLANKTONIC ROTIFERS
OF THE LAURENT1AN GREAT LAKES
By
Douglas W. Grothe
and
Donald R. Grothe*
OCTOBER 1977
U.S. Environmental Protection Agency, Region V
Central Regional Laboratory,
536 South, Clark Street, Chicago, Illinois 60605
*12560 Marine Drive, St. Louis, Missouri 63141
U.S. Environment?! Protection Agswty
fl e?.for. 5, Library (PL-12J)
77 \Vjst Jackson Sputevard, 12th Floor
CiHcaso, tL 60604-3590
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DISCLAIMER
This report has been reviewed by the Central Regional Laboratory,
U.S. Environmental Protection Agency, Chicago, Illinois, and
approved for publication. This report does not signify that the
contents necessarily reflect the views and policies of the U.S.
Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation
for use.
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CONTENTS
Page
Introduction 1-2
Morphology 5-6
Reproduction 7
Collection and Preservation 7-8
Taxonomic List of Planktonic Rotifers 9-14
Key to Genera 15-19
Key to Species 20 -47
Acknowledgements 48
Bibliography 49-53
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INTRODUCTION
Many articles have been published on the zooplankton of the
Laurentian Great Lakes. Most of these studies however, have
concentrated primarily on the larger zooplankters i.e. cladocerans
and copepods. Relatively few comprehensive studies have been made
of the rotifer fauna (Eddy, 1927; Ahlstrom, 1936; Nauwerck, 1972;
Stemberger, 1974; Watson, 1974 and Bricker et al., 1977). The most
recent of these studies {Nauwerck, 1972; Stemberger, 1974; Watson,
1974 and Bricker et al., 1977) have helped to fill many of the gaps
that existed in some of the earlier investigations.
The information contained in this text represents a compilation
of data obtained from earlier taxonomic studies as well as data
collected by the authors in 1975 and 1977. It is the first compre-
hensive report describing the planktonic or "open water" rotifers
present in all the Great Lakes and is limited only to species
identified within the past thirty-five years. Littoral species
found in plankton samples as occasional migrants are also included
in the text. These species are labeled to avoid confusion with
planktonic forms. Lists of the common and uncommon or rare species
and the respective lakes where they have been found appear in Tables
1 and 2, respectively. Organisms were placed in these categories
based on observations by the authors and other taxonomists. It must
be realized however, that spatial, seasonal, and yearly variations
in species abundance and composition do occur in most natural aquatic
systems. Consequently, some species that are common during one year
or season may be uncommon or rare the next. Individuals interested
in some of the earlier taxonomic studies should refer to the biblio-
graphy at the end of the text.
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The taxonomic descriptions concentrate primarily on external
characteristics that are readily observable to aid the general
biologist in keying to the genus and species level. These descrip-
tions are supplemented with drawings or photographs of the appropri-
ate species. The reader is encouraged to also use the taxonomic
keys, many of which have excellent illustrations, cited at the end
of the text.
Although this key is written for the general taxonomist, we
believe the photographs and drawings will also be of value to the
specialist. Rotifer species previously unreported in the Great Lakes
will undoubtedly continue to be discovered as the U.S. and Canadian
governments, state agencies, and universities continue their investi-
gations of the Laurentian Great Lakes.
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Table 1
Common planktonic rotifer species of the Laurentian Great Lakes1
Lake
Species Superior
*Anuraeopsis fissa (Gosse)
Asplanahna herrioki de Guerne
Asplanahna priodonta Gosse
Braahionus angularis Gosse
^Braahionus bidentata Anderson
Braahionus budapestinensis Daday
*Braahionus aalyaifloms Pallas
*Braahionus aaudatus Barrois & Daday
*Braahionus havanaensis Rousselet
*Braahionus uraeolaris Muller
Chromogaster ovalis (Bergendal)
Collotheaa mutabilis (Hudson)
Collotheaa pelagiaa (Rousselet)
Conoahiloides dossuarius (Hudson)
Conoahilus uniaornis Rousselet
Euahlanis dilatata Ehrenberg
Pilinia longiseta (Ehrenberg)
Gastropus sty lifer Imhof
Hexarthra rrrira (Hudson)
Kelliaottia bostoniensis (Rousselet)
Kelliaottia longispina (Kellicott)
Keratella aoahlearis (Gosse)
Keratella aoahlearis f. hispida (Lauterborn)
Keratella aoahlearis f. robusta (Lauterborn)
Keratella aoahlearis f. teata (Gosse)
Keratella arassa Ahl Strom
Keratella earlinae Ahl Strom
Keratella hiemalis Carl in
Keratella irregularis (Lauterborn)
Keratella quadrata (Muller)
Keratella taurooephala Myers
Keratella valga (Ehrenberg)
Notholaa aauminata (Ehrenberq)
Xotholaa foliaaea (Ehrenberg)
Notholaa laurentiae Stemberger
Notholaa squamila (Muller)
Ploesoma hudsoni (Imhof)
Ploesoma Lentiaulare Herri ck
Ploesoma truncation (Levander)
Polyarthra doliahoptera Idelson
Polyar-chra euryptera Wierzejski
Polyarthra mayor Burckhardt
Polyarthra remata Skorikov
Polyarthra vulgaris Carl in
Pompholyx sulaata Hudson
Synahaeta asyrmetriaa Koch-Al thaus
Synahaeta lakowitziana Lucks
Synahaeta oblonga Ehrenberg
Synahaeta peatinata Ehrenberg
Synahaeta stylata Wierzejski
Synahaeta sp.
Triahoaeraa aylindriaa (Imhof)
Triohcaeraa multiarinis CKellicott)
Triahoaeraa pcraellus (Gosse)
Triahoaeraa rous8ele~i (Voigt)
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
LaKe
Michigan
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
V
X
Lake
Huron
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
x
X
X
X
x
x
X
x
X
Lake
St. Clair
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
x
x
X
Lake
Erie
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
V
x
x
X
Lake
Ontario
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
X
x
x
x
X
x
* Generally found in littoral or benthic areas; only occasional migrant in plankton.
1 Species reported from harbor areas are not included.
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Table 2
Uncommon or rare planktonic rotifer species of the Laurentian Great Lakes1
Lake
Species Superior
Aaplmchna 'nerricki de Guerne
AeplanaTma. pyiodonta Gosse
*Braahionua bidentata Anderson
*Braahionus ealyciflorus Pallas
*Braahionus caudatus Barrois & Daday
Brachionus diversiaornis (Daday)
*Brachionus havanaensis Rousselet
*Brachionus quadridentatuB Hermann
*Braahionus rubens Ehrenberg
*$Tachicmu.8 urceolaris Muller
*Cephalodella gibbet (Ehrenberg)
Chromogaster ovalis (Bergendal )
Collofkeca pelagioa (Rousselet)
Conoahiloides dossuarius (Hudson)
Conochilus hippoarepis (Schrank)
*Euahlanis deflexa Gosse
Suchlanis dilatata Ehrenberg
*£-uahlani3 oropha Gosse
*Euahlanis pcava Rousselet
*Enahlani.8 triquetra Ehrenberg
Fi.li.nia terminal-is (Plate)
Gaetropus stylifer Imhof
Hexarthra mira (Hudson)
Kelliaottia bostoniensis (Rousselet)
Keravella aochlecris f. fa.lv.ta Ahlstrom
Keratella aoahlearia f. hisvida (Lauterborn)
Kevatella aoohlearis f. robusta (Lauterfaorn)
Kevatella ooahlearis /. tevta (Gosse)
Keratella hienalis Carl in
Keratella taurooephala Myers
ALecane lima (Muller)
*Lepadella patella (Muller)
*Monostyta bulla Gosse
*Monoetyla lunarie (Ehrenberg)
*Monosfyla quadridsntata Ehrenberg
Hotholca acuminata (Ehrenberg)
Notholaa foliacea (Ehrenberg)
Notholaa squamula CMuller)
*Platyias patulus CMuller)
Ploeeoma hudsoni tlnihof )
Ploesoma tmmaatum (Levander)
PolyartHra euryptera Wierzejski
Pompholyx suloata Hudson
Synahaeta oblonga Ehrenberg
*Teetudinella patina (Hermann)
*Triahocerca lota (Jennings)
Trichoaerca longiseta (Schrank)
*Triahoaerca muaoea (Stokes)
*Triohoaex>aa poroellus (Gosse)
Triatioceraa pueilla Qennings)
Tricnocerca rousseleti (Voigt)
Triahoaepaa aimilis (Wierzejskl)
*Tri<2hooevaa stylata (Gosse)
*Trianotri.a tetractis (Ehrenfaerg)
Tylotroeha monopus CJennings)
Lake Lake
Michigan Huron
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Lake
St. Clair
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Lake
Erie
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Lake
Ontario
X
X
X
X
X
X
X
X
X
X
X
X
X
* Generally found in littoral or benthlc areas; only occasional migrant In plankton,
-* Species reported from harbor areas are not Included.
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MORPHOLOGY
Rotifers exhibit considerable variability in morphology
and are represented by both loricate and illoricate forms. The
rotifer body can generally be differentiated into a head, trunk,
and foot. Figure 1 illustrates some of the general morphological
features characteristic of many species. The anterior end (head)
contains a ciliated corona which functions primarily as a means of
locomotion as well as for directing food into the mouth. A foot may
be present in some species and absent in others. When a foot is
present, it will often bear one or two toes.
Several methods of feeding are displayed among rotifers. One
of the most common methods involves the movement of the coronal cilia
which create small water currents. These currents direct plankton
and detritus into the mouth, whereupon particles of suitable size
are ingested (Pennak, 1953). The food is then mechanically broken
down by the mastax which contains jaw-like structures known as
trophi. Some rotifers obtain their food by thrusting out their
trophi which grasp the prey and directs the food into the stomach.
A third method utilizes the trophi to pierce the prey and then a
"sucking" mechanism to ingest the body contents.
The type of trophi is an important taxonomic feature used to
distinguish rotifer genera. Figure 2 illustrates the eight major
types of trophi: malleate, virgate, forcipate, incudate, ramate,
malleoramate, and uncinate. These structures can be observed by
placing the specimen on a depression microscope slide containing a
10 percent solution of sodium hypochlorite (Chlorox bleach). The
sodium hypochlorite dissolves the soft parts leaving only the trophi
for easy observation CMyers, 1937).
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apical field
Fig. 1: Major morphological structures of Synchaeta grandis (Redrawn from Voigt, 1957).
F«g. 2: 8 major types of rotifer trophi:
A - malleate anterior view; B - malleoramate anterior view; C - ramate anterior view;
D - cadate ventral view; E - incudate anterior view; F - forcipate anterior view;
G - uncinate anterior view; H - virgate ventral view ff - fulcrum; m - manubrium;
r - ramus; u - uncus . (A-H redrawn from Pennak, 1953).
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REPRODUCTION
Most rotifers reproduce by a process known as heterogony which
involves both parthenogenetic development and sexual phases. The
parthenogenetic cycle involves the laying of diploid eggs which do
not require fertilization. The laying of such eggs by the female
aids in the rapid colonization of an area. The sexual phase consists
of the formation of haploid eggs in the female which may or may not
be fertilized by the male. When eggs are not fertilized, they are
released and eventually develop into males (Pennak, 1953). If
fertilization occurs, the dormant eggs that are produced are resistant
to unfavorable environmental conditions. Although most planktonic
forms carry their eggs, other species may lay the eggs in the open
water or on aquatic plants and other surfaces. Some rotifers such
as Asplccnahna give birth to living young.
COLLECTION AND PRESERVATION
The presence of rotifers in a wide variety of habitats makes
it necessary to employ different methods of collection depending upon
whether planktonic, littoral, or sessile forms are desired. Planktonic
species may be obtained by making horizontal, oblique, or vertical
tows with a Mo. 25 (64.0 y) mesh plankton net. A Van Dorn, Niskin, or
other suitable sampling device can be used to collect water samples
in areas that are too shallow or weedy for towing devices. The organ-
isms are then concentrated by filtering the water sample through a
special plankton funnel fitted with a 53 y mesh net (Likens and Gilbert,
1970). This method is also useful for the collection of species too
small to be retained by a No. 25 mesh net and when net clogging is a
problem. Sweeping through the aquatic vegetation with a long handled-
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shallow plankton net is a good method for collection of rotifers
commonly found in littoral areas. Sessile or attached rotifers can
be obtained from material on the bottom such as logs, rocks, etc.,
and from the surface of aquatic plants.
Rotifers are generally preserved in 5 per cent formalin.
Formalin however, will often cause the organism to retract. The
addition of carbonated water in a ratio of 1:20 (carbonated water
to lake water) before the addition of formalin will narcotize the
specimens and thus help prevent retraction of body parts (Gannon and
Gannon, 1975).
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TAXONOMIC LIST OF THE PLANKTON1C ROTIFERS
OF THE LAURENTIAN GREAT LAKES
Class Monogononta
Order Ploima
Family Brachionidae
Subfamily Brachioninae
Genus Anuraeopsis Lauterborn, 1900
* Anuraeopsis fissa (Gosse, 1951)
Genus Brachionus Pallas, 1766
Braahionus angularis Gosse, 1851
* Brachionus bidentata Anderson, 1889
Brachionus budapestinensis Daday, 1885
* Brachionus calyciflorus Pallas, 1766
* Brach-ionus caudatus Barrois and Dady, 1894
Braah-i.or.us diversicornis (Daday, 1883)
* Brachionus havanaensis Rousselet, 1911
* Bra.chi.onu3 quadr-identatus Hermann, 1783
* Braah-ionus rubens Ehrenberg, 1838
* Bvadhionus ia>oeola'?is Muller, 1773
Genus Euohlanis Ehrenberg, 1832
* Suehlanis deflexa Gosse, 1851
* Generally found in littoral, OT ben~hic areas; only occasional
migrant in plankton.
9
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Euchlanis dilatata Ehrenberg, 1832
* Euchlanis oropha Gosse, 1887
* Euahlan-is parva Rousselet, 1892
* Euahlards triquetva Ehrenberg, 1838
Genus KelHoottia AhlStrom, 1938
KelHoottia bcstoniensis (Rousselet, 1908)
KelHoottia longispina (Kellicott, 1879)
Genus Kevatella Bory de St. Vincent, 1822
Ke^atella ooehlearis (Gosse, 1851)
Kevatella aoohleaTis f. faluta Ahlstrom, 1943
Keratella eochlearis f. hispida (Lauterborn, 1898)
Kevatella aodhlearis f. robusta (Lauterborn, 1900)
Keratslla coGhlearis f. teata (Gosse, 1851)
Kevatella erassa Ahlstrom, 1943
Kepatella eaplinae Ahlstrom, 1943
Ke^atella hiemalis Carl in, 1943
Keratella irvegularis (Lauterborn, 1898)
Keratella quadrata (Muller, 1786)
Kevat&lla taurooep'hala Myers, 1938
Kevatella valga (Ehrenberg, 1834)
Genus Notholaa Gosse, 1886
Notholoa aowni,nc.ta (Ehrenberg, 1832)
Notholaa foUacea (Ehrenberg, 1838)
Notholaa laurenflae Stemberger, 1976
Notlwlaa squamula (Muller, 1786)
10
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* Genus Platyias Barring, 1913
* Platyias patulus (Muller, 1786)
* Genus Triahotria Bory de St. Vincent, 1827
* Trichotvia tetvaetis (Ehrenberg, 1830)
Subfamily Colurinae
* Genus Lepadella Bory de St. Vincent, 1826
* Lepadella patella (Muller, 1786)
Family Lecanidae
* Genus Leeane Nitzsch, 1827
* Leoane Ivna (Muller, 1776)
* Genus Monostyla Ehrenberg, 1830
* Monostyla bulla Gosse, 1851
* Monostyla lunaris (Ehrenberg, 1832)
* Monostyla quadridentata Ehrenberg, 1832
Family Notommatidae
* Genus Cephalodella Bory de St. Vincent, 1826
* Cephaladella gibbet. CEhrenberg, 1832)
Family Trichocercidae
Genus TTiekocevea. Lamarck, 1801
TTichoceTca. aylindrioa (Inihof, 1891)
* Triohoceraa lata (Jennings, 1894)
Ti'iohocer-aa longiser-a (Schrank, 1793)
* TpishooeTca mzioosa (Stokes, 1896)
Triahoeerea multiarinis (KelllCOtt, 1897)
* Trichccerca. poi>oellus (Gosse, 1851)
11
-------
Trichocerca pus-ilia (Jennings, 1902)
T-riohoceTca rousselet-i (Voigt, 1902)
Tvichocerca similis (Wierzejski, 1893)
* Trichoceroa stylata (Gosse, 1851)
Family Gastropodidae
Genus Chromogaster Lauterborn, 1893
Chvomogastep ovalis (Bergendal, 1892)
Genus Gastropus Imhof, 1898
Gastropus stylifev Imhof, 1891
Family Tylotrochidae
Genus Tylotrocha Harring and Myers, 1922
Tylotrooha monopus (Jennings, 1894)
Family Asplanchnidae
Genus Asplanchna Gosse, 1850
Asplanchna herriaki de Guerne, 1888
Asplanahna priodonta Gosse, 1850
Family Synchaetidae
Genus Ploesoma Herrick, 1885
Ploesoma hudsoni, (Imhof, 1891)
Ploesoma lentioulare Herrick, 1885
Ploesoma tmrnaatwri (Levander, 1894)
Genus Polyarthra Ehrenberg, 1834
Polyarthra dolichoptei'a Idelson, 1925
Polyarthra eupyptera Wierzejski, 1891
12
-------
Polyarthra major Burckhardt, 1900
Polyarthra remata Skorikov, 1896
Polyarthra vulgaris Carl in, 1943
Genus Synonaeta Ehrenberg, 1832
Synahaeta asymmetriaa Koch-Althaus, 1963
Synonaeta Idkowitziana Lucks, 1930
Synohaeta oblonga. Ehrenberg, 1832
Synonaeta peotinata Ehrenberg, 1832
Synchaeta stylata Wierzejski, 1893
Order Flosculariaceae
Family Testudinellidae
Genus Filinia Bory de St. Vincent, 1824
Filinia longiseta (Ehrenberg, 1834)
Fi.1s-in.-la tewinal-is (Plate, 1886)
Genus Pompholyx Gosse, 1851
Pompholysc sulcata Hudson, 1885
Genus Testudinella Bory de St. Vincent, 1826
* Testudinella patina tHermann, 1783)
Family Hexarthridae
Genus Hexarfhra Schmarda, 1854
Hexarthra mira (Hudson, 1871)
Family Conochilidae
Genus Conoohiloides Hlava, 1904
Conoohiloides dossuarius (Hudson, 1885)
13
-------
Genus Conodhilus Ehrenberg, 1834
Conoohilus hippoovep-is (Schrank, 1803)
Conoehilus unicornis Rousselet, 1892
Order Collothecaceae
Family Collothecidae
Genus Collotheaa Harring, 1913
Collotheoa mutabiHs (Hudson, 1885)
Collotheoa pelagiaa (Rousselet, 1893)
14
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KEY TO THE GENERA OF-PLANKTONIC ROTIFERS
OF THE LAURENTIAM GREAT LAKES
1. Single ovary Class Monogononta 2
Paired ovaries Class Digononta *
2. Foot or foot opening present (foot may be retracted) 3
Foot absent ..... 19
3. Foot segmented 4
Foot unsegmented or annulated 9
4. Foot composed of two segments (first segment in some species
may not be readily observable) 5
Foot composed of three segments (first segment in some
species may not be readily observable) 7
5. Foot terminates in single toe. Anterior margin of lorica
with shallow or deep V-shaped sinus (Plate X).
Monostyla (p. 34)-
Foot terminates in two toes 6
6. Posterior margin of dorsal plate divided medially by
deep inverted U or V-shaped notch (Plates III & IV).
Euohlan-is (p. 23 )•
Posterior margin of dorsal plate not divided medially by
inverted U or V-shaped notch (Plate X).
Leaane (p. 33).
7. Two posterior spines present. Anterior margin with two
or ten spines. Foot opening may be bordered by two short
spines (Plate IX).
Platyias (p. 32).
Posterior spines absent 8
* Representatives cf the class Digononta do not comprise the
connnon rotifer species found in the Great Lakes.
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8. Head and neck region clearly defined from rest of body.
Second foot segment often bears two spines of varying
length (Plate IX).
Triohotria (p. 32).
Head and neck region not clearly defined from rest of
body. Second foot segment lacks spines. Anterior
margin with wide U-shaped sinus (Plate IX).
Lepadella (p. 33).
9. Foot annulated 10
Foot unsegmented, smooth or not annulated 14
10. Foot with one or two short or minute toes 11
Foot without toes, terminates in ciliary band. Two eye
spots present (Plate XVIII).
Testudinella (p. 45).
11. Anterior dorsal margin with two, four, or generally six
spines. Posterior spines often present (Plates I - III).
Braohionus (p. 20)•
Anterior dorsal margin without spines 12
12. Lorica with numerous ridges forming various textures
(Plate XV).
Ploesoma (p. 40).
Lorica not as above 13
13. Body irregularly ovate and compressed laterally. Foot
opening located medially or posteriorly on ventral
plate (Plate XIV).
Gastropus (p. 38).
Body slender and spindle-shaped. Foot located terminally
(Plate XIV).
Tylotroeha (p. 39)-
14. Two toes present 15
Toes absent 17
16
-------
15. Toes of unequal length. Right toe (.dorsal view) obscure
or reduced. Left toe very long (Plates XI - XIII).
Triohoeerca (p. 35).
Toes of equal or nearly equal length 16
16. Body cylindrical. Lateral fissure present along length
of body. Toes long, slender, and tapered to point
(Plate XI).
Cep'halodella (p. 35).
Body conical or vase-shaped. Round prominent ciliated
auricles present on each side of head. Lateral fissure
absent (Plate XVII).
Synohaeta. (p. 42).
17. Lateral antennae prominent 18
Lateral antennae absent or not prominent. Coronal funnel
may or may not have lobes. When present, lobes have
bristles (Plate XX).
Collotheoa. (p. 47).
18. Two lateral antennae located on ventral surface below
corona. Lateral antennae may be fused. Dorsal antennae
small. Body tapers to long unsegmented, retractile
foot (Plate XIX).
Conoahiloides (j)- 46).
Two lateral antennae located on apical field. Lateral
antennae may be fused. Dorsal antennae absent. Body
tapers to long, unsegmented, retractile foot (Plate XIX).
Conoah-ilus CP • 46) .
19. Anterior margin with spines 20
Anterior margin without spines 22
20. Areolate pattern present on dorsal surface. Anterior margin
with six spines. One or two posterior spines often present
(Plates V - VII).
Keratella (p. 25 ).
Dorsal surface smooth or striated, areolate pattern
absent 21
-------
21. Spines on anterior margin bilaterally symmetrical.
Posterior margin rounded or terminates in generally
broad spine of varying length which does not taper
to point in most species (Plate VIII).
Notholaa (p. 30).
Spines on anterior margin located asymmetrically.
Body terminates in long tapered caudal spine (Plate V).
Kellioottia (p.25 ).
22. Body with foliate or paddle-like appendages 23
Body without foliate or paddle-like appendages 24
23. Body with six hollow appendages bearing long bristles at
tips (Plate XIX).
Hexarthra (p. 45).
Body with two bundles of foliate appendages on both the
dorsal and ventral surfaces (Plate XVI).
Polyarthra (p. 41).
24. Anterior margin with two long filaments. Posterior margin
with terminal or subterminal filament-like structure
(Plate XVIII).
Filirtia (p. 44).
Anterior and posterior margins without filament-like
structures 25
25. Distinct keel present. Body oblong or boat-shaped.
Posterior margin truncate or tapered (Plate I).
Anuraeops-is (p. 20).
Keel absent 26
26. Lorica generally with four longitudinal grooves; four-
lobed in cross section (Plate XVIII).
Pompholyx Cp> 44).
Lorica without longitudinal grooves 27
18
-------
27. Body highly transparent with internal organs clearly
visible. Head sparsely ciliated with single row of
cilia (Plate XIV).
Asplanahna (p. 39).
Body not highly transparent. Corona bears finger-
shaped process (Plate XIV).
Chromogaster (p. 38).
-------
-------
KEY TO THE SPECIES OF PLANKTQNIC ROTIFERS
OF THE LAURENTIAN GREAT LAKES
ANURAEOPSIS Lauterborn, 1900
i
Body oblong or boat-shaped. Posterior margin truncate or
tapered. Keel present. Lorica lacks spines. Foot absent. Trophi
malleate.
1. Body oblong and truncated posteriorly.
A large diverging mass-like structure (Webers organ)
may protrude from posterior margin. Total length 92-
105 y (Plate 1,1)-
Generally found in littoral areas; only occasional
migrant in plankton.
Anuraeopsis f-issa
Ref.: Donner, 1943; Gosse, 1851; Pennak, 1953; Sudzuki, 1964.
BRACHIONUS Pallas, 1766
Body shape highly variable; ovate to subrectangular. Lorica
usually divided into a dorsal and ventral plate. Anterior dorsal
margin with two to six spines. Location of foot opening variable
but generally present at posterior end. Foot often retracted.
Foot opening may be bordered by two short spines. Posterior spines
common. Trophi malleate.
1. Lateral and intermediate anterior spines obscure or reduced.
Lateral and intermediate anterior spines not obscare or
reduced 3
20
-------
2. Posterior spines present.
Body ovate. Anterior dorsal margin with two small
median spines separated by U-shaped aperture. Foot open-
ing a U-shaped aperture in ventral plate. Posterior
spines broad and of variable length. Total length
122-354 y (Plate 11,2).
Generally found in littoral areas; only occasional
migrant in plankton.
Braehionus cauda.'bus
Posterior spines absent.
Body ovate. Anterior dorsal margin with two small
median spines separated by a U-shaped opening. Foot
opening large, often variable in shape and bordered
by two short spines. Total length 91-202 u (Plate 1,2).
Brachionus angularis
3. Lateral anterior spines much longer than median anterior
spines 4
Lateral anterior spines equal to or shorter than median
anterior spines 6
4. Anterior dorsal margin with six spines 5
Anterior dorsal margin with four spines.
Body ovate. Two unequal, diverging posterior spines
present. Right posterior spine (dorsal view) usually
longer than left but may be of nearly equal length.
Total length 304-565 y (Plate 11,3).
Bracnionus diversieormis
5. Right posterior spine (dorsal view) generally much longer than
left posterior spine.
Body oblong or subrectangxilar. Intermediate anterior
spines minute. Distance between bases of posterior spines
is small. Total length 135-350 y (Plate 11,4).
Generally found in littoral areas; only occasional
migrant in plankton.
Braehionus havanaensis
21
-------
PLATE I
Figs. 1-4: 1. Anuraeopsis fissa dorsal view; 2. Brachionus angularis ventral view; 3. B. bidentata
ventral view; 4. B. budapestinensis dorsal view. (1 redrawn from Donner, 1943).
-------
PLATE II
I
* a*
•% ,
1 *»
Figs. 1-4: 1. Brachionus calyciflorus dorsal view; 2. B. caudatus ventral view; 3. B. diversicornis
ventral view; 4. B. havanaensis dorsal view.
-------
-------
Posterior spines of nearly equal length.
Body subrectangular. Intermediate anterior spines ,
shorter than lateral and median anterior spines. Well-
developed sheath projects from foot opening. Total
length 175-578 y (Plate 1,3).
Generally found in littoral areas; only occasional
migrant in plankton,
Braohicnus bidentata
6. Anterior dorsal margin with six spines ...7
Anterior dorsal margin with four spines 9
7. Body oblong or ovate 8
Body subrectangular.
Median spines often much longer than lateral and
intermediate spines. Medians divergent and separated
by V-shaped opening. Two posterior spines of variable
length usually present. Total length 188-418 y (Plate
111,1).
Generally found in littoral areas; only occasional
migrant in plankton.
Braeh-icnus quadr-identatus
8. Lorica smooth, without pattern.
Median and intermediate spines exhibit distinctive
asymmetric shape: anterior portion is narrow but then
diverges markedly outward to form broad base. Median
spines separated by deep U-shaped opening. Intermediate
spines shorter than medians. Foot opening in ventral
plate truncate-oval or V-shaped. Posterior spines absent.
Total length 154-274 y (Plate 111,2).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Braohionus zttbens
Lorica with wavy longitudinal lines.
Resembles Braohicnus Pubens however, anterior dorsal
spines are nearly symmetrical in shape and do not exhibit
peculiar form discinctive of 3'^aahionus i^be^s. Foot
22
-------
opening on ventral plate generally large and oval-
shaped; shape however, variable. Total length 185-
280 u (Plate 111,3).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
BTadhionus
9. Postero-lateral spines present.
Body oblong or subrectangular. Foot opening often
bordered by two spines. Total length 180-570 y (Plate
11,1).
Generally found in littoral areas; only occasional
migrant in plankton.
Bvaohionus oalye-iflorus
Postero-lateral spines absent.
Body oblong. Foot opening with V-shaped aperture
in dorsal plate. Total length 115-170 y (Plate 1,4).
........ Braahionus budapestinens-is
Ref.: Ahlstrom, 1940; Gosse, 1851; Pejler, 1957; Pennak, 1953
Sudzuki, 1964.
SUCHLANIS Ehrenberg, 1832
Body ovate in ventral view. Anterior margin of lorica trun-
cate; posterior margin rounded. Dorsal plate shield-like. Post-
erior margin of dorsal plate divided medially by deep inverted U
or V-shaped notch. Foot composed of two segments. Second seg-
ment bears two toes which are tapered. Trophi malleate.
1. Dorsal anterior margin with distinct notch.
Posterior margin rounded or with only shallow
indentation. Foot broad. Two pairs of long setae
present on dorsal end of first foot joint. Toes short
and stout. Body length 280 y (Plate 111,4).
Generally found in littoral areas; only occasional
migrant in plankton.
Eiieklan-is deflexa
23
-------
PLATE III
Figs. 1-4: 1. Brachionus quadridentatus dorsal view; 2. B. rubens ventral view; 3. B. urceolaris
ventral view; 4. Euchlanis deflexa ventral view. (2,3 redrawn from Ahlstrom, 1940; 4 redrawn
from Myers, 1930).
-------
-------
Dorsal anterior margin with only shallow indentation 2
2. Toe length over one-third body length.
Resembles Euahlanis dilatata however, body smaller.
Foot slender. Toes long and slender. Toes sharply point-
ed. Body length 125-140 p (Plate IV,4).
Generally found in littoral areas; only occasional
migrant in plankton.
Euchlan-is parva
Toe length one-third or less body length 3
3. Dorsal plate highly arched.
Posterior margin with distinct inverted V-shaped
notch. Foot slender. One pair of long setae present
on distal end of first foot joint. Toes slender. Toe
length approximately one-third length of dorsal plate.
Body length 180-240 y (Plate IV.5&6).
Generally found in littoral areas; only occasional
migrant in plankton.
Euohlanis triquetra
Dorsal pi ate not hi ghly arched 4
4. Foot slender.
Posterior margin with deep inverted U-shaped notch.
One pair of long setae present on distal end of first
foot joint. Toes slender. Toe length approximately one-
third length of dorsal plate. Body length 170-270 y
(Plate IV, 1&2).
Eudhlanis dilatata
Foot broad.
Resembles Euahlanis dilatata. Toe length approxi-
mately one-fourth length of dorsal plate. Toes sharp-
ly pointed. Body length 180-200 y (Plate IV,3).
Generally found in littoral areas; only occasional
migrant in plankton.
Euehlanis cpopha
Ref.: Amren, 1964; Bulow, 1954; Gosse, 1851; Herrick, 1885;
Myers, 1930; Pajler, 1962a; Wulfert, 1956.
24
-------
KELLICOTTIA Ahlstrom. 1938
i
Body conical, terminating in very long caudal spine. Anter
ior dorsal margin with four to six spines of varying length.
Spines located asymmetrically. Foot absent. Trophi malleate.
1. Anterior dorsal margin with four spines.
Total length 364 y (Plate V,l).
bo stamens-is
Anterior dorsal margin with six spines.
Total length 460-795 y (Plate V,2).
Kelliaottia long-isp-ina
Ref.: Ahlstrom, 1938; Amren, 1964; Arnemo et. al., 1968; Nauwerck,
1972; Pennak, 1953.
KERATELLA Bory de St. Vincent, 1822
Anterior dorsal margin with six spines. One or two post-
erior spines generally present. Spine1 located medially on
posterior margin when only one posterior spine present. Dorsal
and ventral plates covered with fine areolate pattern of com-
plete and incomplete polygons (irregular pentagons and hexa-
gons, Fig. 3). Pustulation often present. Trophi malleate.
1. Lorica terminates in two posterior spines 2
Lorica not as above 4
2. Posterior spines approximately equal length 3
Posterior spines of unequal length.
Left spine (dorsal view) may be absent. If present,
25
-------
PLATE IV
Figs. 1-6: 1. Euchlanis dilatata ventral view; 2. £ dilatata lateral view; 3. £ oropha ventral view;
4. £ parva ventral view; 5. £ triquetra lateral view; 6. £ triquetra ventral view. (1-6 redrawn
from Myers, 1930).
-------
PLATE V
'"»
4- •* \».
>'' '*" *'<•''''
Figs. 1-4: 1. Kellicottia bostoniensis dorsal view; 2. /C. longispina dorsal view; 3. Keratella
cochlearis dorsal view; 4. A", cochlearis /! /a/ufa dorsal view. (3, 4 redrawn from Ahlstrom, 1943).
-------
Keratella cochlearis
Kerateffa crassa
Keratella earlinae
m
Keratella inegularis
Keratella quadrata
Fig. 3: Dorsal pattern of several Keratella species:
a - antero-carinal polygon; b - postero-carinal polygon; c - lateral polygon; d - median line;
e - medio-carina! polygon; f - median anterior spine; g - intermediate anterior spine;
h - lateral anterior spine; i - accessory antero-median polygon; j - medial polygon;
k - accessory postero-carinal polygon; ! - pustules; m - antero-median polygon;
n - meso-median polygon; o - postero-median polygon; p - lateral ridge.
{Redrawn from Ahlstrom, 1943).
-------
left spine shorter than right spine. Total length
130-295 u (Plate VII,4).
Keratetla valga
3, Lateral ridges of postero-median polygon branched.
Body subrectangular. Lorica terminates in two
nearly equal divergent or slightly bowed posterior
spines. Dorsal pattern: row of three polygons located
medially the length of dorsal plate. The first two
median polygons are hexagons, while the third is
generally incomplete (Fig. 3,E). Total length 224-
385 y (Plate VII,2).
Kera-tella quadrata
Lateral ridges of postero-median polygon not branched.
Body subrectangular. Dorsal pattern: similar to
Keratella cruadfata. Total length 100-200 u (Plate
VI,6).
Kevatella hiemal-is
4. Lorica terminates in single median posterior spine 5
Posterior spine absent.
Body oblong. Posterior margin rounded. Median
spines on anterior dorsal margin longer than lateral
spines.-Dorsal areolate pattern similar to Keyatetta
oooh^earis (Fig. 3,A). Total length 89-125 p (Plate
VI,3).
teata
5. Lorica densely hispid.
Dorsal pattern similar to Xeratella acohiearis
(Fig. 3, A) but is obscured by numerous spinelets.
Median posterior spine thin. Median line on dorsal
surface approximately straight its entire length.
Total length 130-225 y (Plate VI, 1).
cochleae-is f. hispida
Lorica not as above ............................................ 6
27
-------
PLATE VI
Figs. 1-6: 1. Keratella cochlearis f. hispida dorsal view; 2. K. cochlearis f. robusta dorsal view;
3. K. cochlearis f. tecta dorsal view; 4. /C. crassa dorsal view; 5. /C. earlinae dorsal view;
6. /C. hiemalis dorsal view. (2, 4 redrawn from Ahlstrom, 1943; 6 redrawn from Pejler, 1962).
-------
-------
PLATE VII
3 4
Figs. 1-4: 1. Keratella irregularis dorsal view; 2. K. quadrats dorsal view; 3. K. taurocephala
dorsal view; 4. K. valga dorsal view lateral anterior spines distorted . (1 redrawn from Ahlstrom,
1943).
-------
6. Median line on dorsal surface straight or has slight indent-
ation towards right behind antero-carinal polygons
Median line on dorsal surface indents to left near second
pair of antero-carinal polygons; beyond these polygons the
line indents to the right.
Dorsal pattern: antero-carinal polygons typical of
KeTate'lla. aoohlear-Ls are mesially divided forming two
pairs of polygons (.antero-carinal and ntedio-carinal
polygons; Fig. 3,B). Hexagons located posterior to
antero-carinal polygons are often completely enclosed.
Total length. 140-244 u (Plate VI, 4).
Kevatetta crassa
7. Lateral anterior spines widely divergent with tips that curve
i nward.
Lorica terminates in broad, moderately long poster- .
ior spine which may diverge to right. Lateral spines
on anterior dorsal margin generally longer than median
spines. Median spines curve outward. Dorsal pattern
similar to Keyatella QOoh1eca"ls (Fig. 3,A). Total length
182-270 u (Plate VII,3).
Keratella taurooephala
Lateral anterior spines not as above 8
8. Dorsal pattern: pentagon located medially (slightly off to
right) between antero-carinal polygons and the two pair of
posterior polygons (postero-carinal and accessory postero-
carinal polygons, Fig. 3,D).
Large pustules present on dorsal and ventral sur-
faces. Pustules on dorsal plate randomly distributed
while those on ventral plate primarily concentrated
on upper third of body. Total length 152-212 u (Plate
VII,!.).
Kevatel'ia irz>3gul
-------
9. Dorsal pattern: Hexagon located above medial polygon and
between antero-carinal polygons (Fig. 3,C).
Medial polygon is a hexagon situated medially
(slightly off to right) between antero-carinal polygons
and the two pair of posterior polygons (postero-carinal
and accessory postero-carinal polygons). Left antero-
carinal polygon is an irregular pentagon. Pustulation
prominent. Total length 120-240 y (Plate VI, 5).
................................ Keratello.
Dorsal pattern not as above ................................... 10
10. Lateral and intermediate spines converge at tips.
Median spines on anterior dorsal margin longer than
lateral spines. Median line present on lower two-thirds
of dorsal surface, terminating at base of posterior spine.
This line may diverge abruptly to right for short distance
near middle of body. Dorsal pattern: One pair of complete
hexagons located medially (antero-carinal polygons , Fig. 3, A) .
Hexagons (postero-carinal polygons )situated posterior to
antero-carinal polygons generally incomplete but may be
fully formed. Two or three pairs of lateral polygons locat-
ed to side of antero-carinal and postero-carinal polygons.
Pustules present on dorsal surface. Total length 92-214 y
(Plate V,3).
.Heratella ooohlearis?-
2There is considerable doubt among many taxonomists regard-
ing the validity of separating Keratetla cochleares into var-
ieties as some investigators have done in the past. This is
primarily due to the phenomenon of cyclomorphosis which has been
observed for this species. Briefly, cyclomorphosis involves a
change in morphology with changing environmental conditions. For
example, winter forms of KeTatella aochleapis often have long
spines which diminish in length as summer approaches. The dorsal
pattern may also exhibit considerable variability. The use of
these characteristics as important taxonomical features for dist-
inguishing varieties is thus questionable for this species. Con-
sequently, morphological variations of Kevatella aoahlecaris are
designated in this text as forms of the species. The reader is
encouraged to consult the works of Ahlstrom (1943), Gallagher
(1957), Nauwerck (1972), and Pejler (1957 and 1962b) which dis-
cuss in detail cyclomorphosis, theories presented for its oc-
currence, and taxonomical problems resulting from this process.
29
-------
Lateral and intermediate anterior spines do not converge
at ti ps 11
11. Postero-carinal polygons complete-
Lorica terminates in long median posterior spine
and usually larger than typical Keratella oochlear-ls.
Anterior spines are also larger. Median line on dorsal
surface may be straight or have slight indentation
towards right behind antero-carinal polygons. Three
pairs of lateral polygons located to side of antero-
carinal polygons. Total length 185-260 u (Plate VI,2).
Keratel'La cochleaz>'i,s f. robusta
Postero-carinal polygons incomplete.
Lorica terminates in moderately long median post-
erior spine.Dorsal pattern very distinct; similar
to Keratella aoo'h'learis (Fig. 3,A). Total length 185-
320 v (Plate V,4).
Qoohleapis f. faluta
Ref.: Ahlstrom, 1943; Amren, 1964; Chengalath et. al., 1971;
Nauwerck, 1972; Pejler, 1957, 1962c; Sudzuki, 1964; Wulfert,
1956.
NOTHOLCA3 Gosse, 1886
Body oblong-ovate, elongate or conical. Anterior dorsal mar-
gin with six spines. Posterior end of lorica rounded or terminates
in generally broad spine of varying length which in most species does
not taper to point. Dorsal plate either smooth, pustulated, or striat-
ed. Foot absent. Trophi malleate.
3Species differentiation is often confusing in the genus
Notholea due to the wide variety of morphological forms that
generally appear in the literature for a particular species.
A revision in the species classification is needed. The reader
is encouraged to consult Pejler (1957) for a discussion on
some of the taxonomic problems encountered with this genus.
3d
-------
1. Body elongate 2
Body obi ong or ovate 3
2. Lorica terminates in broad posterior spine of varying length
which does not taper to point.
Total length 137-260 y (Plate VIII, 1).
Notholca acuminata
Lorica terminates in generally short narrow spine which tapers
to point.
Total length 160-180 y (Plate VIII,2).
Notholca foliacea
3. Intermediate and median anterior dorsal spines longer than
lateral anterior spines.
Dorsal plate striated. Posterior end of lorica
rounded or truncate. Total length 192-285 y (Plate
VIII,3).
Notholca laurentiae1*
Intermediate anterior dorsal spines shorter than lateral and
median anterior spines.
Dorsal plate not striated. Posterior end of
lorica rounded. Total length 100-180 y (Plate VIII,4).
Notholca squamula
Ref.: Amren, 1964; Carlin, 1943; Chengalath et. al., 1971; Nauwerck,
1972; Stemberger, 1976.
^Notholca laurentiae has recently been described as a new
species by Stemberger, 1976. Many Great Lakes taxonomists
have previously identified this species as N. striata.
31
-------
PLATE VIII
Figs.1-4: 1. Notholca acuminata dorsal view; 2. N. foliacea dorsal view; 3. N. laurentiae dorsal
view; 4. /V. squamula dorsal view.
-------
PLATIIAS Harring, 1913
Body subrectangular or ovate. Anterior margin with two or
ten spines. Two broad posterior spines present. Foot opening
may be bordered by two short spines. Trophi rnalleate. (Mote:
some taxonomists include members of this group in the genus
Braah-ionus) .
1. Anterior margin with ten spines.
Body subrectangular. Median spines longest and :
curve outward. Foot opening located asymmetrically
on posterior margin and bordered by two short spines .
Total length 165-265 y (Plate IX,!)-
Generally found in littoral areas; only occasional
migrant in plankton.
................................ Platyias patulus
Ref.: Ahlstrom, 19AO; Pennak, 1953.
TEICEOTRIA Bory de St. Vincent, 1827
Body conical or spindle-shaped. Dorsal plate enlarged to
form shield-like structure around body. Neck region clearly de-
fined from rest of lorica. Foot composed of three segments. Two
spines often present on second segment. Third foot segment bears
two long toes which taper to point. Small spine may be present
between toes. Trophi malleate.
1. Small spine not present between toes.
Second foot segment bears two spines of varying
length. Body length 200-350 u (Plate IX, 2).
Generally found in littoral areas; only occasional
migrant in plankton.
tetractis
Ref.: Herrick, 1385; Ruttner-Kolisko, 1974; Wulfert, 1956.
32 .
-------
LEPADSLLA Bory de St. Vincent, 1826
Body ovate or oblong. Anterior and posterior margins with
U or V-shaped sinus. Foot composed of three segments. Third
foot segment bears two moderately long toes which taper to
point. Trophi malleate.
1. Anterior ventral margin with deep V-shaped sinus, the sides
of which curve slightly outward.
Anterior dorsal margin with wide U-shaped sinus.
Posterior dorsal margin with shallow V-shaped aperture.
First and second foot segments approximately equal
length but shorter than third segment. Toe length about
one-third length of lorica. Body length 100-108 y
(Plate IX,3).
Generally found in littoral areas; only occasional
migrant in plankton.
Lepadella patella
Ref.: Harring, 1917; Pejler, 1962a; Wulfert, 1956.
LECANE Nitzsch, 1827
Body ovate or oblong. Anterior dorsal margin with shallow
or deep V-shaped sinus. Foot composed of two segments. First
segment may not be readily observable. Second segment bears two
toes which taper to point. Trophi malleate.
1. Toes approximately one-third total length.
Body ovate. Anterior dorsal margin with deep V-
shaped sinus. Body length 125-135 u (Plate X,l).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
...., ..,....., Leaane tuna
Ref.: Harring and Myers, 1926.
33
-------
PLATE IX
Figs. 1-3: 1. Platyias patulus dorsal view; 2. Trichotria tetractis lateral view; 3. Lepadella patella
ventral view. (3 redrawn from Edmondson, 1959).
-------
PLATE X
Figs. 1-4: 1. Lecane luna ventral view; 2. Monostyla bulla ventral view; 3. M. lunaris ventral
view; 4. M, quadridentata ventral view. (1 redrawn from Harring and Myers, 1926).
-------
MONOSTYLA Ehrenberg, 1830
Body ovate or oblong. Anterior dorsal margin with shallow
or deep V-shaped sinus. Foot composed of two segments. First
segment may not be readily observable. Second segment
bears single long toe which is much longer than foot segments.
Toe tapers to point. Trophi malleate. (Note: some taxoncmists
include members of this group in the genus Lecane).
1. Lorica width approximately three-fifths length 2
Lorica width approximately three-fourths length.
Body broadly ovate. Anterior dorsal and ventral
margin with deep V-shaped sinus. Dorsal sinus border-
ed by two broad outcurved spines on each side of
opening. First and second foot segments narrow and
oblong. Toe length approximately one-third total length.
Body length 130-142 y (Plate X,4).
Generally found in littoral or benthic areas; only
occasional migrant in plankcon.
Monostyla quacfr'identata
2. Anterior dorsal margin with V-shaped sinus bearing a median
notch.
Body oblong. Anterior ventral margin with deep
V-shaped sinus rounded at posterior margin. First
foot segment small. Second segment larger than first,
triangular in shape. Toe length approximately one-
third total length. Body length 112-113 y (Plate X,2).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Monostyla bulla
Anterior dorsal margin with V-shaped sinus rounded posteriorly,
Body broadly ovata. First foot segment small and
obscure. Second segment large and rectangular. Toe
length approximately one-third total length. Body
length 100-118 u (Plate X,3).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Mono sty la lunaris
34
-------
Ref.: Gosse, 1851; Harring and Myers, 1926; Herrick, 1885.
CEPHALODELLA Bory de St. Vincent, 1826
Body cylindrical. Head and tail regions clearly defined
from rest of body. Lateral fissure present along length of
body. Foot small and bears two toes. Trophi virgate.
1. Toe length approximately one-third total length.
Foot conical. Toes long, slender and taper to
point. Total length 250-300 y (Plate XI,1).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Cephalodella gibbet
Ref.: Harring and Myers, 1924; Wulfert, 1956.
TEICEOCERCA Lamarck, 1801
Body generally cylindrical but asymmetric. Anterior dorsal
margin often with one or two spines of varying length. Foot short
and conical. Two unequal toes present. Right toe (dorsal view)
often obscure or reduced. Left toe generally very long; may be
approximately as long as body. Small substyles usually present
adjacent to toes. Trophi virgate.
1. Anterior dorsal margin with spines or "tooth-like structures"...2
Anterior dorsal margin without spines or "tooth-like
structures" 7
2. Anterior dorsal margin with only one spine or "tooth-like
structure" .- 3
35
-------
PLATE XI
Figs. 1-4: 1. Cephalodella gibba lateral view; 2. Trichocerca cylindrica lateral view; 3. T. fata
dorsal view; 4. 7. long/seta lateral view. (1 redrawn from Marring and Myers, 1924; 3 redrawn
from Jennings, 1902).
-------
Anterior dorsal margin with two or more spines or "tooth-
like structures" ............................................... 4
3. Tip of anterior spine bends downward over anterior opening
of lorica to form hook.
Body long and cylindrical. Head region set off
from lorica by shallow groove. Right toe minute or
absent. Left toe approximately as long as body. Small
substyle present on left side of main toe. Body length
260-355 y (Plate XI, 2).
eyl-indr-iea
Tip of anterior spine not as above.
Body broadly ovate. Anterior dorsal margin ex-
tended to form triangular "tooth-like structure".
Anterior region with numerous longitudinal folds.
Posterior margin of lorica symmetrical. Right toe
reduced and extends obliquely across base of left
toe. Left toe approximately one-half to two-thirds
length of body. Minute substyle present on each side
of left toe. Body length 180-200 y (Plate XII, 2).
multi-ar-in-is
4. Two anterior spines present
Nine anterior spines present.
Body short and cylindrical. Head region set-off
from body by shallow groove. Toes close together, ap-
pearing at times that only one toe is present. Right
toe shorter than left toe. Left toe approximately one-
third length of body. Body length 95 y (Plate XIII,1).
5. Body short, broad, cylindrical and strongly curved.
Head region set-off from body by shallow groove.
Single dorsal ridge present. Toes nearly equal in length.
Length of left toe approximately equal to diameter of
body. Two substyles present at base of each toe. Bod3r
length 140-175 y (Plate XII,3).
Generally found in littoral areas; only occasional
migrant in plankton.
Tnanooevoa
36
-------
Body not as above 6
6. Two dorsal ridges present.
Body long and cylindrical. Right spine considerably
longer than left spine. Right toe absent. Left toe ap-
proximately two-thirds length of body or longer. Small
scale-like substyles present on each side of toe. Body
length 300 y (Plate XI,4).
Triahoeeraa longiseta
Dorsal ridges absent.
Body elongate and cylindrical. Length of toes ap-
proximately equal. Toe length less than one-half body
length. Body length 150-200 y (Plate XIII,2).
Triahoeeroa sinril-Ls
7. Anterior margin with folds 8
Anterior margin smooth, without folds 9
8. Left toe length less than one-third body length.
Body short and cylindrical. Right toe absent. Body
length 180 y (Plate XIII,3).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Triehoceroa stylata
Left toe length more than one-third body length.
Body short, broad and cylindrical. Right toe absent.
Left toe length approximately four-fifths body length
but variable. One short substyle present adjacent to toe.
Body length 85-110 y (Plate XII,4).
Trichoceraa pusi-lla
9. Two distinct dorsal ridges extend approximately to middle of
lorica.
37
-------
PLATE XII
Figs. 1-4: 1. Trichocerca mucosa dorso-dextral view; 2. 7". multicrinis lateral view;
3. 7. porcellus lateral view; 4. T. pusilla lateral view. (1, 3, 4 redrawn from Jennings, 1902).
-------
-------
PLATE XIII
Figs. 1-3: 1. Trichocerca rousse/eti lateral view; 2. 7. similis dorsal view; 3. J. styfata lateral
view. (1-3 redrawn from Jennings, 1902).
-------
-------
Body broadly oblong. Right toe uinate. Left toe
approximately as long as body. Three or four substyles
present adjacent to left toe. Body length 180-200 y
(Plate XII,1).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Iyiehcse?aa rrrueosa
Dorsal ridges absent or not as above.
Body broadly ovate. Posterior oargin of lorica
asymmetrical. Foot set off on left side of body. Left
toe approximately four-fifths length of body. Three
short unequal substyles present adjacent to toe. Body
length 170-180 u (Plate XI,3).
Generally found in littoral or benthic areas; only
occasional migrant in plankton.
Trichoasraa Iota.
Ref.: Gosse, 1851; Jennings, 1902; Nauwerck, 1972; Pejler, 1962;
Ruttner-Kolisko, 1974; Stokes, 1896; Wulfert, 1956.
CEROMOGASTER Lauterborn, 1893
Body ovate or sacciform. Lorica divided into dorsal and
ventral plate. Corona bears finger-shaped process. Ciliated
papillae present on apical field. Foot absent. Trophi virgate.
Body length 100-200 y (Plate XIV.l).
Onlyr one species Ckpomogaster oval-Is
Ref.: Carlin, 1943; Chengalath et. al., 1971; Pennak, 1953; Ruttner-
Kolisko, 1974.
GASTSGPUS Imhof, 1898
Body irregularly ovate and compressed laterally. Foot
opening located medially or near posterior portion of ventral
38
-------
plate. Foot annulated. One or two toes present. Toe(s) short
and tapered to point. Trophi virgate.
1. Foot opening located medially on ventral plate.
Foot terminates in single toe. Body length 75-
205 \i (Plate XIV,2).
Gastropus styl-ifer
Ref,: Pejler, 1957; Ruttner-Kolisko, 1974; Sudzuki, 1964.
TILOTRGCHA Marring and Myers, 1922
Body slender and spindle-shaped, bulging markedly outward
near mid-length then tapering posteriorly. Head region separ-
ated from body by shallow groove. Two dorsal antennae present.
Foot moderately long and annulated. Only one toe present.
Trophi virgate. Total length 175-250 u (Plate XIV,3).
Only one species Ty to trochee, monopus
Ref.: Edmondson, 1959; Earring and Myers, 1924.
ASPLANCHNA Gosse, 1850
Body sacciform and highly transparent. Internal organs
clearly visible. Head sparcely ciliated with single row of cilia.
Foot absent. Trophi incudate. Body length 420-1500 y.
1. Pedal gland present near urogenital opening (Plate XIV,4).
Asp'tanchna "nervlaki
Pedal gland absent (plate XIV,5).
Asplanchna. p-riodonta
Ref.: Gosse, 1850; Herrick, 1885; Ruttner-Kolisko. 1974: Sudzuki, 1964,
39
-------
PLATE XIV
Figs. 1-5: 1. Chromogaster ova/is dorsal view; 2. Gastropus stylifer lateral view; 3. Tylotrocha
monopus dorsal view; 4. Asplanchna herricki lateral view; 5. A. priodonta lateral view. (3 redrawn
from Marring and Myers, 1924; 4, 5 redrawn from Voigt, 1957).
-------
-------
PLOESOM*. Herrick, 1885
Body oblong. Dorsal surface convex; ventral surface convex
or flattened. Lorica with ridges forming various textures. Dor-
sal plate may be extended anteriorly to form head shield. Foot
opening located medially on ventral plate. Foot large and annul -
ated. Two toes present. Toes short, approximately equal length
and taper to point. Trophi virgate.
1. Head shield present ,
Head shield absent.
"Size large, with frothy looking epidermis which
gives the thin flexible lorica an areolate appearance"
(Edmondson, 1959). Body length 250-600 y (Plate XV,1).
Ploesoma kudsoni
2. Head shield with small, broad spine located medially on anter-
ior margin.
Dorsal surface with one pair of short transverse
ridges located slightly posterior to middle of lorica.
Anterior to these markings are two ridges which diverge
to anterior margin of lorica; Posterior to transverse
lines are two ridges, one on each side of median line.
Body length 150-300 y (Plate XV,2&3).
Ploesoma lenti-oulca'e
Head shield without spines.
Dorsal surface with ridges forming large medial
triangle. Situated adjacent to the two lateral sides
of triangle are two pairs of ridges. The inner pair
converge near posterior margin of lorica. The outer
pair of ridges converge but do not meet, terminating
at posterior margin. Body length 130-300 u (Plate XV54&5).
Ploesoma. truncation
Ref.: Edmondson, 1959; Herrick, 1885; Nauwerck, 1972; Ruttner--
Kolisko, 1974; Wulfert, 1956.
-------
POLIARTHM Ehrenberg, 1834
Body subrectangular or subsquare. Illoricate. Anterior
third of body with two bundles of foliate or fin-like appendages
on both the dorsal and ventral surfaces. A generally distinct
midrib extends almost entire length of each fin. Foot absent.
Trophi virgate.
1. Fins very broad; fin width 50-70 y.
Fins entend only short distance beyond end of body.
Ratio (in percent) of fin length to body length 100-
110. Body length 160-180 u (Plate XVI, 2).
........................... Polyarthra
Fins slender or very narrow, fin width less than 50 y .......... 2
2. Fins extend well beyond posterior end of body .................. 3
Fins generally extend only slightly beyond posterior end
of body [[[ 4
3. Fin width one- tenth fin length.
Ratio (in percent) of fin length to body length 120-
170. Body length 90-130 y (Plate XVI, 1).
doliohoptez>a
Fin width less than one- tenth fin length.
Ratio (in percent) of fin length to body length 120-
150. Body length 65-100 y (Plate XVI, 4).
Polyarfkra. vemata
4. Body length 140-195 y.
Fins slender; fin width 20-40 y. Ratio (in percent) of
fin length to body length 100-110 (Plate XVI, 3).
-------
PLATE XV
Figs. 1-5: 1. Ploesoma hudsoni lateral view; 2. P. lenticulare dorsal view; 3. P lenticulare lateral
view; 4. P. truncatum dorsal view; 5. P. truncatum lateral view. (2 redrawn from Edmondson,
1959; 3 redrawn from Chengalath et. al., 1971).
-------
-------
PLATE XVI
-^
.. ^ ^^1**»;^« V; ^', 1
'* *~**k^f*&
jrf
Figs. 1-5: 1. Polyarthra dolichoptera dorsal view; 2. P. euryptera dorsal view; 3. P. ma/or dorsal
view; 4. P. remata dorsal view; 5. P. vulgaris dorsal view.
-------
-------
Body length 90-145 p.
Fins slender. Ratio (in percent) of fin length to
body length 100-110 CPlate XVI,5).
Polyartkra vulgcori-s
Ref.: Carlin, 1943; Edmondson, 1959; Nauwerek, 1972; Pejler, 1957;
Pourriot, 1965; Ruttner-Kolisko, 1974; Sudzuki, 1964.
SZNCHAETA5 Ehrenberg, 1832
Body conical or vase-shaped. Round prominent ciliated auricles
present on each side of head. Apical field generally elevated above
coronal cilia. Four styli present on apical field. One or two eyes
present. Lateral antennae located on posterior margin of body.
Foot unsegmented. Two toes present. Toes short, approximately equal
length and taper to point. Trophi virgate.
1. Foot very broad.
Body elongate and conical. Toes minute. One toe
often retracted. Total length 275-290 \i (Plate XVII,1).
, Syna'haeta asymmetriaa
Foot not as above 2
2. Teeth present on each uncus of trophi 3
Teeth absent on each uncus of trophi.
Body large, broad and sub-conical. Two fleshy ciliated
protuberances present on top of apical field. Foot short
and stout, terminating in two minute toes. Lateral antennae
5Species differentiation in the genus Synohaeta is
often difficult. The body shape, which is one of the
primary distinquishing characteristics used by taxonomists
to distinquish species is generally distorted in preserved
samples. Examination of trophi characteristics and the spec-
imen in the unpreserved state may be required for species
identification.
42
-------
situated on ventral side of body. Total length 340-
408 y (Plate XVII,4).
Synahaeta peat-inata
3. Distinct notch divides row of smaller teeth on uncus into two
groups (i.e. Two groups of three or one group of three and
another group of four).
Body small, conical and swollen at sides. Resembles
Synahaeta lakowitziana but smaller and sides are more
pronouncely swollen. Lateral antennae situated one-third
from posterior end of body and slightly ventral in position.
Foot bears two minute toes. Total length 200-244 y (Plate
XVII,3).
Synahaeta oblonga
Row of teeth on uncus not divided into two groups by a distinct
notch 4
4. Foot long and narrow.
Body elongate and conical. Foot bears two minute toes.
Lateral antennae situated approximately one-third from
posterior end of body, and slightly ventral in position.
Total length 242-292 y (Plate XVII,5).
Synahaeta stylata
Foot not as above.
Body conical and only slightly swollen at sides. Foot
bears two minute toes which are widely separated from each
other. Lateral antennae situated one-third from posterior
end of body. Each uncus of trophi bears one anterior tooth
which is clearly separated from row of smaller teeth. The
number of teeth in this row numbers six on one uncus and
seven on the other. Total length 250-280 y (Plate XVII,2).
Synahaeta lakowLtz-Lana
Ref.: Hauer, 1952; Koch-Althaus, 1963; Lucks, 1930; Pejler, 1957,
1962c; Pourriot, 1965; Rousselet, 1902; Ruttner-Kolisko, 1974;
Sudzuki, 1964.
43
-------
PLATE XVII
Figs. 1-5: 1. Synchaeta asymmetrica dorsal view; 2. S. lakowteiana dorsal view; 3. S. oblonga
dorsal view; 4. S. pectinata dorsal view; 5. S. stylata dorsal view. (1 redrawn from Koch-
Althaus, 1963; 2. redrawn from Lucks, 1930; 3-5 redrawn from Rousselet, 1902).
-------
-------
FILINIA Bory de St. Vincent, 1824
Body ovate. Anterior region with two filament or bristle
like structures of varying length which originate below head
region. Posterior region with terminal or subterminal filament.
Foot absent. Trophi malleoramate.
1. Posterior region with subterminal filament located on ventral
surface.
Filament more than 5 y from posterior end of body.
Body length 145-208 y (Plate XVIII,!).
FiUnici. long-lseta
Posterior region with terminal filament.
Filament located no more than 5 y from posterior end
of body. Body length 145-208 y (Plate XVIII,2).
Filinia. terminal-is
Ref.: Chengalath et. al., 1971; Edmondsons 1959; Nauwerck, 1972;
Pejler, 1957; Sudzuki, 1964.
POMPHOLYX Gosse, 1851
Body ovate or oblong. Longitudinal grooves may be present or,
lorica. Two eye spots present. Eggs attached behind body after
deposition by thread-like secretion. Foot absent. Trophi malleo-
ramate.
1. Lorica with four longitudinal grooves; body four lobed in
cross section.
Total length 120 y (Plate XVIII,3).
Pontpholyx sulaata
Ref.: Edmondson, 1959; Gosse, 1851; Hudson, 1885.
44
-------
TESTUDINELLA Bory de St. Vincent, 1826
Body ovate or conical, flattened and transparent. Head region
funnel-shaped, but generally withdrawn into body in preserved spec-
imens. Stomach kidney-shaped. Long prominent band of muscle located
on each side of stomach extends from sides of head to posterior third
of body. Two eye spots present. Foot opening located medially or
posteriorly on ventral plate. Foot long, annulated and retractile;
terminating in ciliary band. Trophi malleoramate.
1. Foot opening round and located medially on ventral plate.
Body ovate. Body length 120-300 \i (Plate XVIII,4).
Generally found in littoral areas; only occasional
migrant in plankton.
Testudinella pat-ina
Ref.: Herrick, 1885; Pennak, 1953; Wulfert, 1956.
BEXMIEM Schmarda, 1854
Body with six hollow appendages originating on upper third
of body. Long bristle-like structures bearing small spines pre-
sent at end of arms. Trophi malleoramate.
1. Corona expanded ventrally to form "lip" which extends over base
of ventral arm.
Body length 300 v (Plate XIX,1).
Hexarthra m-ira
Ref.: Bartos, 1948; Pennak, 1953.
45
-------
PLATE XVIII
\y tT~'^%^***»v—«;' •
••:'?-S
Figs. 1-4: 1. Filinia long/seta lateral view; 2. £ terminate lateral view; 3. Pompholyx sulc'ata
ventral view; 4. Testudinella patina ventral view.
-------
-------
PLATE XIX
Figs. 1-4: 1. Hexarthra mira lateral view; 2. Conochiloides dossuarius lateral view;
3. Conochilus hippocrepis lateral view; 4. C. unicornis lateral view. (1 redrawn from Pennak,
1953; 2-4 redrawn from Voigt, 1957).
-------
-------
CONOCHILOILES Klava, 1904
Body conical, tapering to long, unsegmented retractile foot,
Two lateral antennae located on ventral surface below corona.
Antennae may or may not be fused. Dorsal antennae small. Gelat-
inous mass often surrounds foot and lower part of body. Toes
absent. Trophi malleoramate.
1. Lateral antennae fused.
Total length highly variable (Plate XIX,2).
Conodhi1oi.de s dossuarius
Ref.: Chengalath et. al., 1971; Edmondson, 1959; Pennak, 1953.
CONOCHILUS Ehrenberg, 1834
Body vase-shaped, tapering to long, unsegmented retractile
foot. Two lateral antennae located on apical field. Antennae
may or may not be fused. Toes absent. Individuals often found
in colonies, although may be solitary in plankton. Trophi
malleoramate.
1. Lateral antennae separate.
Total length highly variable CPlate XIX,3).
Conochtlus h-ippccrep-is
Lateral antennae fused.
Total length highly variable (Plate XIX,4).
Conoa'nilus unicornis
Ref.: Chengalath et. al., 1971; Edmondson. 1959; Pejler, 1957;
Pennak, 1953.
46
-------
COLLOTEECA Harrlng, 1913
Body spindle-shaped, tapering to long, unsegmented, retract-
ile foot. IIloricate. Coronal funnel may or may not have lobes.
When present, lobes have long bristles. Tip of foot tapered or
has thickening. Trophi uncinate.
1. Coronal funnel with dorsal and ventral lobes.
Dorsal lobe with two eye spots. Foot with thick-
ening at tip. Total length 300-455 \i (Plate XX,1).
Collotheea rmtdbilis
Coronal funnel without lobes.
Five fleshy prominences with short radiating setae
located within ciliated corona. Eyes absent. Foot tapered.
Total length 300-500 u (Plate XX.2&3).
Collotheca pelagiea
Ref.: Hudson, 1885; Pejler, 1957; Rousselet, 1893; Ruttner-Kolisko,
1974; Sladecek, 1968.
47
-------
PLATE XX
* *
Figs. 1-3: 1. Collotheca mutabilis\atera\ view; 2. C. pelagica view inside corona from above;
3. C. pelagica lateral view. (1 redrawn from Edmondson, 1959; 2 redrawn from Rousselet, 1893).
GPO 6I7-99B
-------
-------
ACKNOWLEDGEMENTS
We are greatly indebted to Drs. C.H. Fernando, Univeristy of
Waterloo; D. Gilbertson, University of Minnesota; G.G. Mulamocttil,
University of Waterloo; Mr. R. Stemberger, University of Michigan-
Pellston; and Mr. N. Thomas, U.S. Environmental Protection Agency-
Large Lakes Study for their critical reviews and helpful suggestions
Special thanks is expressed to Mr. J. Bricker, University of
Michigan-Pellston; Mr, R. Chengalath, National Museum of Natural
Science-Ontario; Dr.C.H. Fernando; Ms, D. Larson, Center for Lake
Erie Area Research; and Ms. P. Wade, McMaster University for
providing some of the specimens to photograph, and to Miss Birute
Bulota, U.S. Environmental Protection Agency - Region V.
-------
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;..; S. £r .
H'igion 5. Library (PL-12J)
53 '7 Wast Jackson Boulevard, 12tn Flo*
Chicago, IL 60604-3590
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