United States
             Environmental Protection
             Agency
           Environmental Monitoring and
           Support Laboratory
           Cincinnati OH 45268
EPA-600/3-82-033
April 1982
             Research and Development
x>EPA
A Guide to the
Fresh water Tubificidae
(Annelida:  Clitellata:
Oligochaeta) of
North America

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                                                            EPA-600/3-82-033
                                                            April 1982
A GUIDE TO THE FRESHWATER TUBIFICIDAE  (ANNELIDA:  CLITELLATA:  OLIGOCHAETA)

                             OF NORTH AMERICA
                                    by
                             Kurt S. Stimpson
                        Ecological  Analysts,  Inc.
                      Suite 306, 1535 Lake Cook Road
                       Northbrook,  Illinois   60062
                             Donald J. Klemrn
                         Aquatic Biology Section
             Environmental Monitoring and Support Laboratory
                   U.S.  Environmental  Protection Agency
                         Cincinnati, Ohio   45268
                                   and
                             Jarl  K. Hiltunen
                           3160 Pitts view Drive
                        Ann Arbor, Michigan  48104
             ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
                    OFFICE OF RESEARCH AND DEVELOPMENT
                   U.S.  ENVIRONMENTAL PROTECTION AGENCY
                         CINCINNATI, OHIO  45268
                    U.S. Environmental Protection Agency
                    Region 5, Library (PL-12J)
                    77 West Jackson Boulevark 12th Floor
                    Chicago,  IL  60604-3590

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                                 DISCLAIMER
     This report has been reviewed by the Environmental Monitoring and
Support Laboratory, U.S.  Environmental Protection Agency, and approved
for publication.  Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
                                     11

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                                  FOREWORD

    Environmental measurements are required to determine the quality of
ambient water, the character of effluents, and the effects of pollutants
on aquatic life.  The Environmental Monitoring and Support Laboratory -
Cincinnati conducts an Agency -wide quality assurance program to assure
standardization and quality control of systems for monitoring water and
wastewater and conducts research to develop, evaluate, and promulgate
methods to:

    *   Measure the presence and concentration of physical, chemical, and
        radiological pollutants in water, wastewater, bottom sediments,
        and solid waste.
    *   Concentrate, recover, and identify enteric viruses, bacteria, and
        other microorganisms in water.
    *   Measure the effects of pollution on freshwater, estuarine, and
        marine organisms, including the phytoplankton, zooplankton,
        peri phy ton, macrophyton, macroinvertebrates, and fish.
    *   Automate the measurement of physical, chemical, and biological
        quality of water.

    The effectiveness of measures taken to maintain and restore the
biological integrity of the Nation's surface waters is dependent upon our
knowledge of the changes in the taxonomic composition of aquatic life
caused by discharges of toxic substances and other pollutants, and upon
the level of our understanding of the complex relationships that prevail
in aquatic ecosystems.  Tubificid worms are important components of the
benthic fauna and are frequently abundant in a variety of freshwater
habitats.  The varied response of tubificid species to different kinds of
pollution and toxic substances makes them very useful as water quality
indicator organisms.  While several regional keys to North American
Tubificidae have been published, this manual is the first to contain an
illustrated key and the distribution for all taxa.  The publication was
developed to assist aquatic biologists in evaluating data collected in
studies of the effects of toxic substances and other pollutants on the
communities of benthic macroinvertebrates.
                           Robert L. Booth
                           Acting Director
                           Environmental Monitoring and Support
                           Laboratory - Cincinnati


                                    iii

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                                 ABSTRACT
     In North America, the freshwater annelid worms (Clitellata:
Oligochaeta), belonging in the family Tubificidae, are composed of 18
genera, 54 species, one subspecies, and several  variant forms.  All taxa
can be identified by external  and internal morphological features.  This
guide presents an introduction to the general biology of the Tubificidae,
collecting and processing methods, a species list, an artificial
illustrated key, a glossary, an annotated systematic list, and a selected
bibliography which includes the references cited in the text and other
publications which provide additional information on tubificid taxonomy
and ecology.
                                     iv

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                                  CONTENTS

Foreword	Ill
Abstract	iv
Figures	v1
Acknowledgments 	   x
    1.  Introduction	   1
    2.  Methods	   3
            Collection, Preservation, and Preparation
               of Tub1f1c1dae Whole Mounts	   3
            Depository for Tublflcld Worms	   4
    3.  Species List	   5
    4.  Key to the Freshwater Tub1f1c1dae of North America
               (North of Mexico)	   9
            Introduction	   9
            Key to the Tub1f1c1dae	12
    5.  Glossary	41
    6.  Annotations	44
Selected Bibliography 	  53
Index to Scientific Names	60

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                                  FIGURES
Number                                                                Pages
    1     Generalized tubificid,  illustrating external  and  internal
         anatomical  terminology, lateral  view	10
    ?.    Generalized tubificid,  illustrating types  of  somatic  and
         genital  chaetae and anatomical  terminology	11
    3    Branchiura  sowerbyi, dorsal  and ventral  gill  filaments  on
         posterior segments	13
    4    Granular-opaque, densely papillate dermis  of  Spirosperma
         nikolskyi	13
    5    Quistadrilus multisetosus:   (a,b)  slightly opaque dermis with
         scattered papillae	13
    6    Clear dermis, without papillae	14
    7    Ouistadrilus multisetosus,  dorsal  pectinate chaeta	14
    8    . multisetosus, posterior  ventral chaeta  	  14
    9    j). multisetosus:  (a) anterior  ventral  chaeta;  (b) posterior
         ventral  chaeta	14
   10    Spirosperma ferox, dorsal  pectinate chaeta	15
   11     S^ beetoni:  (a) anterior ventral  chaeta;  (b) posterior
         ventral  chaeta	15
   12    _S. nikolskyi, posterior ventral  chaeta	16
   13    _S. carolinensis, posterior  ventral chaeta	16
   14    Ilyodrilus  mastix, anterior end illustrating  enlarged
         mouth	16
   15    Aulodrilus  pigueti, posterior dorsal crotchet chaeta:
         (a) facial  aspect; (b)  lateral  aspect 	  17
   16    Potamothrix vejdovskyi: (a) anterior dorsal crotchet and
         capilliform chaetae; (b) spermathecal chaeta	18

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Number                                                                Pages
   17    Rhyacodn'lus brevidentatus, dorsal  crotchet chaeta	18
   18    Aulodrilus plurlseta:  (a) ventral  crotchet chaeta;
         (b) dorsal pectinate chaeta 	 19
   19    Rhyacodrilus coccineus:  (a) dorsal crotchet chaeta;
         (b) penlal chaetae	19
   20    Psammoryetides barbatus,  pectinate  anterior dorsal crotchet
         chaeta	20
   21    Rhyacodrilus montana:  (a) anterior dorsal  pectinate chaeta;
         (b) anterior ventral crotchet chaeta	20
   22    Tubifex harmani, posterior dorsal crotchet chaeta 	 21
   23    Rhyacodrilus punctatus, anterior ventral  chaeta 	 21
   24    Tubifex nerthus, anterior ventral chaeta	22
   25    T_. tubifex, penis bulb, atrium, and vas deferens	23
   26    Haber cf. speciosus:  (a) penis sheath; (b) penial chaeta;
         (c) spermathecal chaeta	24
   27    Potamothrix bedoti,  specialized chaeta	24
   28    Psammoryctides minutus, penial chaeta 	 25
   29    Rhyacodrilus soda!is, dorsal pectinate chaeta 	 25
   30    Psammoryctides convolutus, spermathecal chaeta	26
   31    . californianus, spermathecal chaeta 	 26
   32    Potamothrix hammoniensis, spermathecal chaeta 	 26
   33    . bavaricus, spermathecal chaeta 	 26
   34    Varichaeta pacifica:  (a) penis sheath inverted;
         (b) penis sheath everted	27
   35    Tubifex superiorensis, penis sheath 	 28
   36    Ilyodrilus templetoni;  (a) penis sheath  with distal  end
         absent; (b) penis sheath  with distal  end  present	28
   37    Tubifex kessleri americanus, penis  sheath 	 28
   38    Ilyodrilus frantzi form capillatus, penis sheath	28
                                    vii

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Number                                                                Pages
   39.   Telmatodrilus vejdovskyi;   (a) anterior ventral chaeta;
         (b) posterior ventral  chaeta	29
   40    Aulodrilus amerlcanus, posterior dorsal crotchet chaeta .... 29
   41    Aulodrilus limnobius,  posterior dorsal  crotchet chaeta:
         (a) facial aspect;  (b) lateral aspect 	 30
   42    Monopylephorus he! obi us, crotchet chaeta	30
   43    Bothrioneurum vejdovskyanum, SEM of prostomium showing
         sensory cavity	31
   44    B. vejdovskyanum;   (a) ventral crochet chaeta of segment II;
         Tb) ventral  crochet chaeta of segment XXX; (c) penial chaeta. . 31
   45    Isochaetides curvisetosus, posterior dorsal  chaeta	32
   46    Limnodrilus  udekemianus:  (a,b,c) ventral  chaetae in segment
         II, illustrating variation in shape 	 32
   47    Isochaetides freyi;  (a) penis sheath;  (b) spermathecal
         chaeta	33
   48    Rhizodrilus  lacteus;  (a)  specialized chaeta in segment IX;
         {b) specialized chaetae in segment XI	33
   49    Potamothrix  moldaviensis:   (a) spermathecal  chaeta;
         partially everted  penis; (c) fully everted penis	34
   50    Phallodrilus hallae, penial  chaeta	35
   51    Rhyacodrilus falciformis,  penial chaeta:  (a) lateral
         aspect; (b)  facial  aspect 	 35
   52    Limnodrilus  rubripenis, penis sheath	37
   53    L_. angustipenis, penis sheath	37
   54    L_. hoffmeisteri (spiralis form), penis sheath	37
   55    _L. psammophilus, penis sheath	37
   56    U udekemianus, penis sheath	37
   57    ^. profundicola, penis sheath 	 37
   58    L. silvani,  penis  sheath.	39
                                   viii

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Number                                                                 Pages
   59    . hoffmeisteri (variant form), illustrating two pern's
         sheath types:(a) scalloped margin; (b) scalloped margin
         with irregular distal projection	39
   60    L_. hof fmei steri, penis sheath	39
   61    L_. claparedianus, penis sheath	39
   62    L_. maumeensis, penis sheath 	  39
   63    L- cervix (variant form), penis sheath	39
   6*    i.' cervix, penis sheath	39
                                    ix

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                              ACKNOWLEDGMENTS
     The authors thank Ralph 0. Brfnkhurst, Thomas V. Clevenger, and
Michael S. Loden for their reviews of the technical contents of the
manuscript.  We also thank Cornelius I. Weber for reading the manuscript
and making valuable suggestions.  We are grateful to Kristian Fauchald of
the Smithsonian Institution, U.S. National Museum of Natural History,
Department of Invertebrate Zoology, Division of Worms, Washington, D.C.
for permitting us to examine the collections of Tubificidae.  We are also
indebted to the following individuals for supplying specimens and
distribution records:  Ralph 0. Brinkhurst, Dale F. Kriewall, Michael S.
Loden, Anthony F. Maciorowski, Bruce E. Markert, Bruno Vincent, and Mark
J. Wetzel.  We extend special thanks to Douglas R. Spencer for his
contributions in early stages of preparation of the guide.  We would also
like to thank Peter M. Chapman for the use of Figure 43.

     The secretarial assistance of Cordelia Nowell and Diane Schirmann is
gratefully acknowledged.

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                                 SECTION 1

                                INTRODUCTION
    The relationship between benthic macroinvertebrate community
structure and the physical and chemical characteristics of aquatic
habitats has been examined in great detail in the past several decades.
The body of knowledge relating the qualitative and quantitative responses
of benthic communities to changes in habitat has grown to the point where
an examination of benthic community structure has become a valuable tool
for regulatory agencies, water resource managers, and aquatic ecologists
in assessing and monitoring water quality and detecting pollution
sources.  The Oligochaeta, or segmented worms, are an important component
of the benthic community in nearly every freshwater biotope.  The group
comprises 24 families, among which the Tubificidae are the most widely
distributed and abundant oligochaetes in freshwater systems.  The utility
of the Tubificidae for monitoring and detecting changes in water quality
and physical habitats has been illustrated by several authors (Brinkhurst,
1966, 1970, 1974a,b; Lang and Lang-Dobler, 1980; Stimpson, et al.,
1975).  Compared to other macroinvertebrate groups, the Tubificidae are
particularly well-suited for use in biological assessments of water
quality, water pollution, or other changes in aquatic ecosystems
resulting from natural causes or man's activities.  Members of the family
live longer than many other invertebrate forms; are generally sedentary
infaunal forms and, as opposed to, for example, most aquatic insects, are
restricted to the aquatic environment throughout their life cycle.  Most
importantly, the habitat and water quality requirements as well  as the
pollution tolerance of many species have been documented in the
literature (Chapman, Parrel 1, and Brinkhurst, 1982a,b; Hiltunen, 1967,
1969a, 1969b; Howmiller and Beeton, 1970).

    Unfortunately, the Tubificidae have often been overlooked or ignored
in sample processing or misidentified by investigators not familiar with
their taxonomy.  In many instances, investigators have recorded the group
only as subclass (Oligochaeta), family, or merely as "worms."  The
inadequate treatment of the family represents a loss of valuable
ecological information that may be attributed, at least in part, to the
misconception that the group is taxonomically very difficult, and to the
lack of a practical key to the species.

    Thus, the guide was composed to assist the USEPA and other biologists
in Federal, state, and private water monitoring organizations in
identifying specimens of tubificid worms to species.  The guide will  aid
in the monitoring and detection of changes in water quality and the
effects of toxic substances and other pollutants on macroinvertebrate

                                     1

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community structure.  It will  also facilitate an expansion of our
knowledge of the ecological  requirements of some of the lesser known
tubificid species.  The guide includes a discussion of methods for the
collection, preparation, and examination of specimens, a species list, an
artificial  illustrated key,  a glossary, an annotation for each species,
and a selected bibliography.  Morphological features utilized in the
differentiation of species are defined in the glossary.  The reader is
referred to Brinkhurst and Jamieson (1971) and Reynolds (1977) for
additional  morphological terms.  The selected bibliography was assembled
from literature pertaining directly to the systematics and ecology of the
Tubificidae of North America.

    Inasmuch as new zoogeographical records are published frequently,
this guide may not include the latest North American discoveries.  In
instances where a species is not keyed in the present work, the reader is
directed to consult Brinkhurst and Jamieson (1971), Aquatic Oligochaeta
of the World.  Complete descriptions that may be helpful in confirming
the identity of most species in this guide, may also be found therein.

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                                 SECTION 2

                                  METHODS


COLLECTION, PRESERVATION, AND PREPARATION OF TUBIFICIDAE WHOLE MOUNTS

    Tuhificidae may be collected using any of a variety of methods,
ranging from qualitative hand-picking and dip-netting to quantitative
dredge, grab or core sampling.  Using most conventional collection
methods, it is necessary to reduce the volume of sediment in order to
discern and sort the organisms.  Although Agency procedures for
macroinvertebrate studies (Weber, 1973) recommend screening the sample on
a U.S. Standard No. 30 mesh sieve (28 meshes per inch, 0.595 mm
openings), it should be noted that many small individuals may be lost
during the sieving process and that use of a finer sieve (for example,
No. 60 mesh) or no sieving at all may be required to insure collection of
all individuals.  Great care should be taken in sieving samples
containing worms; too vigorous agitation may break specimens or damage
body parts required for species identification.  Tubificidae collected by
selective hand-picking in the field may be fixed and preserved by placing
them directly in 5% formalin.  Sieved samples may, depending on the
volume of sediment retained, require a slightly greater concentration of
formalin (10%) to assure adequate preservation.  Use of alcohol as a
fixative should be avoided because worms initially preserved in alcohol
without first being fixed in formalin tend to deteriorate.

    The initial sorting of specimens from sediment residue should be done
at 5-10X using a dissection microscope or magnification lens.  Even when
sieving has been accomplished carefully, some individuals will fragment.
To avoid possible overcount in quantitative studies, only head-end
sections and whole worms should be enumerated.  Forceps are commonly
employed to remove specimens from the sieve residue.  The sorted
oligochaetes may be stored indefinitely in sealed vials containing 5-10%
formalin.  Additional instructions for sorting macroinvertebrate samples
can be found in the USEPA Biological Methods Manual (Weber, 1973).

    To identify oligochaetes to species, they must be cleared and mounted
on glass slides for examination under a compound microscope capable of
magnification up to 1000X.  An 18 mm diameter, No. 0 or 1 round cover
glass is appropriate because it will adequately accommodate nearly the
size range of tubificids and the shape allows for maneuvering the
specimen into the most desired position by gentle rotation of the cover
glass.  When preparing a temporary or permanent slide mount, an attempt
should be made to place the specimen on its side, thereby, revealing both
dorsal and ventral fascicles of chaetae.  It may be necessary to apply

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gentle pressure on the cover glass to flatten the specimen to render the
important anatomical  features more readily visible.  Depending on the
need of the investigator, a variety of clearing agents, media, and
mounting procedures may be employed.  The simplest method is to mount
specimens directly in a permanent nonresinous medium (for example,
Hydramountl, or CMC^) that contains a clearing agent.  This method
allows rapid processing of specimens, but further handling of specimens
is rendered difficult because of the permanence of the mount.
Alternatively, specimens can be cleared in a solution of Amman's
lactophenol (Brinkhurst, 1968), prepared by combining lOOg phenol, lOOmL
lactic acid, 200mL glycerine, and lOOmL water.  Clearing of specimens in
Amman's lactophenol may be accomplished either in a stoppered vial or by
mounting them temporarily on glass slides and covering with a round
coverglass.  The clearing process usually takes a few hours to a few days
depending on the size and preservation of the specimens.  Gentle
application of heat will speed the clearing process.

    If the specimens are preserved in 70% alcohol, they should be placed
in 30% alcohol and then in water for a short time to leach out the
alcohol.  The alcohol retards the clearing process of Amman's
lactophenol.  However, do not leave specimens in the water too long (not
more than 2 hours) because the worms will begin to deteriorate.
Tubificids can be held indefinitely in Amman's lactophenol or 10%
formalin for later processing and mounting.  After clearing, the
specimens can be examined directly or removed and mounted in a permanent
medium.  Optimal resolution and longevity of mounted material are
achieved only in resinous media (for example, Canada balsam, Harleco's
Coverbond^ for xylene, and so forth).  These mounting media require
dehydration of the specimens through the alcohol series before using the
mountant, but they produce the best permanent mounts.  This method can be
found in standard biological techniques sourcebooks.  Nonresinous media
are recommended for rapid processing of large numbers of specimens, but
for a few or for important reference materials, resinous mounting media
are best.  Longevity in the quality of a mounted specimen can be
increased by sealing the margin of the cover glass with clear fingernail
lacquer.


DEPOSITORY FOR TUBIFICID WORMS

    Tubificid material no longer needed in a study should be deposited in
an appropriate museum.  In North America, the specimens with proper
collection data can be sent to the Division of Worms, Department of
Invertebrate Zoology, U.S. National Museum of Natural History,
Smithsonian Institution, Washington, D.C.  20560.
iBio/Medical Specialities (P.O. Box 1687, Santa Monica, CA 90406)
2Master's Chemical Co. (P.O. Box 2382, Des Plaines, IL 60018)
Scientific Products (1430 Waukegan Road, McGaw Park, IL 60085)

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                                 SECTION  3
                               SPECIES LIST
Phylum Annelida
 Class CHtellata
  Subclass Oligochaeta
   Order Haplotaxida
    Suborder Tubificina
      Family Tubificidae
      Genus Aulodrilus Bretscher,  1899
        Aulodrilus americanus  Brinkhurst  and  Cook,  1966
        Aulodrilus' limnobius Bretscher, 1899
        Aulodrilus pigueti  Kowalewski. 1914
        Aulodrilus' pluriseta  (Piguet,  1907)
      Genus Bothrioneurum Stole,  1886
        Bothrioneurum vejdovskyanum Stole, 1886
      Genus Branchiura Beddard, 1892
        Branchiura sowerbyi Beddard, 1892
      Genus Haber Holmquist, 1978
        Haber cf.  speciosus (Hrabe,  1931)
      Genus Ilyodrilus Eisen,  1879
        Ilyodrilus frantzi  Brinkhurst, 1965
        Ilyodrilus' frantzi  form capillatus Brinkhurst and Cook, 1966
        Ilyodrilus rnastix Brinkhurst,  1978
        Ilyodrilus tempietoni  (Southern,  1909)
      Genus Isochaetides Hrabe, 1966
        Isochaetides curvisetosus  (Brinkhurst and Cook, 1966)
        Isochaetides freyi  (BrTnkhurst, 1965)
      Genus  Limnodrilus  Claparede, 1862
        Litnnodrilus  angustipenis Brinkhi
        Limnodrilu?  cervix Brinkhurst, 1963
Limnodrilus angustipenis Brinkhurst and Cook,  1966
                   Brii

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  Limnodrilus cervix (variant form)
  LimnodriTu? claparedianus Ratzel, 1868
  Limnodrilus hoffmeisteri Claparede, 1862
  Limnodrlfu? hoffmeisteri (spirails form)
  LimnodriTu? hoffmeisteri (variant form)
  Limnodrifus" maumeensis Brinkhurst and Cook, 1966
  Limnodrilu? profundicpla (Verrill, 1871)
  Limnodritui? psammophllus Loden,  1977
  Limnodrilus rubripenis Loden,  1977
  Limnodrilus silvani  Eisen, 1879
  Limnodrilii? udekemianus Claparede, 1862

Genus Monopylephorus Levinsen, 1884

  Monopylephorus he!obi us Loden, 1980

Genus Phallodrilus Pierantoni, 1902

  Phallodrilus hallae  Cook and Hiltunen, 1975

Genus Potamothrix Vejdovsky and  Mrazek, 1902

  Potamothrix bavaricus  (Oschmann, 1913)
  Potamothri'x bedoti fPiguet. 1913)
  Potamothrix hamrnoniensis (Michaelsen, 1901)
  Potamothrix' moldaviensis Vejdovsky and Mrazek,  1902
  Potamothrix vejdovskyi (Hrabe, 1941)

Genus Psammoryctides Hrabe, 1964

  Psammoryctides barbatus (Grube,  1861)
  Psammoryctides califprnianus Brinkhurst, 1965
  Psammoryctides convolutus Loden, 1978
  Psammoryctides minutus Brinkhurst, 1965

Genus Quistadrilus Brinkhurst, 1981

  Quistadrilus multisetosus (Smith 1900)

Genus Rhizodrilus Smith, 1900

  Rhizodrilus lacteus  (Smith, 1900)

Genus Rhyacodrilus Bretscher, 1901

  Rhyacodrilus brevidentatus Brinkhurst, 1965
  Rhyacodrilus coccineus (Ve'jdovsky, 1875)
  RhyacodrilTi? falciformis Bretscher, 1901
  RhyacodriTuT montana (Brinkhurst, 1965)
  Rhyacodrilus punctatus Hrabe',  1931
  RhyacodriTirs" soda!is (Eisen, 1879)

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Genus Splrosperma Brinkhurst, 1981

  Splrosperma beetoni (Brinkhurst, 1965)
  Splrosperina" carol1nens1s (Brinkhurst, 1965)
  Splrosperma ferox (Elsen, 1879)
  Spirosperma~ nlkolskyl (Lastockln and Sokolskaya, 1953)

Genus Telmatodrllus E1sen, 1879

  Telmatodrilus vejdovskyl Elsen, 1879

Genus Tublfex Lamarck, 1816

  Tublfex harmanl Loden, 1979
  Tublfex Ignotus (Stole, 1886)
  Tublfex kessleri amerlcanus Brinkhurst and Cook, 1966
  Tublfex nerthus (Michael sen, 1908)
  Tublfex superlorensls (Brinkhurst and Cook, 1966)
  Tubifex tubifex (Muller. 1774)

Genus Varlchaeta Brinkhurst,  1981

  Varichaeta nevadana (Brinkhurst, 1965)
  Varlchaeta paclflca Brinkhurst.  1981

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                                  SECTION  4

      KEY TO FRESHWATER  TUBIFICIDAE  (ANNELIDA:  CLITELLATA:  OLIGOCHAETA)
                      OF NORTH  AMERICA (NORTH OF  MEXICO)
INTRODUCTION

      Phylogenetic relationships within the Tubificidae are poorly known.
Generic limits within the family are based primarily on the configuration
of internal reproductive organs observable only in dissected or
differentially stained and sectioned material.  A natural, phylogenetic
key to the Tubificidae, therefore, would require extensive preparation of
individual specimens and would be wholly unworkable for the aquatic
biologist interested only in determining the identity of specimens within
a given collection.  The key provided herein was constructed, therefore,
on artificial bases using only external and internal features readily
observable in simple whole-mounted material using a conventional light
microscope.  The key allows the user to proceed directly to the species
level of classification without keying out the genera.  For discussions of
phylogenetic relationships and taxonomic limits of genera, the reader is
instructed to consult recent taxonomic literature; for example, Baker and
Brinkhurst, 1981; Brinkhurst, 1979b, 1979c, 1981; Brinkhurst and Jamieson,
1971; Holmquist, 1978, 1979; and Loden, 1977, 1978, 1979) cited in the
Selected Bibilography.

      The principal features used to identify tubificids in this guide are
the somatic chaetae, specialized genital chaetae, and structures of the
male reproductive system.  Chaetae occur in paired fascicles or bundles
located ventro-laterally, "ventral chaetae," and dorso-laterally, "dorsal
chaetae" (Figure 1).  A variety of chaetal types occur.  Generalized
chaetae and their designated terminology are illustrated in Figure 2.
Segments are identified by Roman numerals.  An important point to note is
that segment I, which includes the peristomium, and mouth, and to which
the prostomium is connected, is devoid of chaetae.  Therefore, to
determine the numerical position of each segment, one must count chaetal
fascicles, either dorsal  or ventral, posteriad beginning in segment II.
This is particularly important in locating the genital segments X and XI
that bear the spermathecae and male pores, respectively.

      A number of tubificid species must be sexually mature to be
identified to species.  At two points within the key, the necessity for
mature specimens is noted.  In each case, if specimens in question are
immature, unidentifiable immature reporting categories are provided.   Two
points need to be emphasized in this regard:  first, the majority of
individuals within any assemblage may be immature and, therefore, reported

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                                                                  11

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 only  as unidentifiable;  second,  the composition of the immature components
 can  generally  be  assumed to reflect the species composition of the mature,
 identifiable individuals, present in the same collection.


 KEY  TO THE TUBIFICIDAE

 1      Capilliform chaetae (Fig.  2)  present in anterior (segments II-V)
           dorsal  fascicles	2

       Capilliform chaetae not  present in anterior dorsal  fascicles. .  .   37

 2(1)   Each segment,  posterior  to approximately segment XXX, bears a
           dorsal  and ventral gill  filament (Fig.  3)	
           	  Branchiura sowerbyi

       Posterior segments bear  no gill  filaments 	 3
Fig. 3.  Branchiura sowerbyi, dorsal and ventral gill filaments on
         posterior segments.
                                    12

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3(2)  Dennis opaque or nearly opaque,  appearing  to be  densely  papillate
          and encrusted with sediment  materials  (Fig.  4)  r dermis  coarse
          perhaps slightly opaque and  beset with some  scattered  papillae
          (Fig.  5a,b).  Prostomium often retractile and capilliform
          chaetae frequently stout and sabre-like	4

      Dermis clear (Fig. 6), or at most, slightly opaque  but without
          encrusted sediment materials or papillae.  Prostomium  rarely
          retractile, capilliform chaetae rarely sabre-like	9
                                                       5a
               5b
Fig. 4.  Granular-opaque, densely papillate dermis of Spirosperma
         nikolskyi.
Fig. 5.  Quistadrilus multisetosus:  (a,b) slightly opaque dermis with
         scattered papillae.
Fig. 6.  Clear dermis, without papillae.

                                    13

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4(3)
Dermis coarse but not opaque and without appearance of encrusted
    sediment materials; variously beset with scattered short,
    finger-like papillae.   Papillae often most readily visible
    posteriad to approximately segment XI.  Anterior dorsal
    fascicles composed of  stout sabre-like capilliform and
    distinctly pectinate chaetae (Fig. 7)	
      Dermis opaque or nearly opaque, appearing encrusted with sediment
          materials, densely papillate.  Dorsal crotchet chaetae often
          difficult to differentiate	
5(4)
Anterior and posterior ventral  chaetae similar in shape,  distal
    tooth longer than proximal  tooth (Fig.  8).  [See Annotations.] .
    	  Qulstadrilus multisetosus (in  part)

Anterior and posterior ventral  chaetae differ in shape (Fig.  9a,b).
    Posterior chaetae thick,  with  distal  tooth shorter and much
    thinner than proximal  tooth.   [See Annotations.] 	
    	  Quistadrilus multisetosus (in  part)
                           8
                                         9a
9b
Fig. 7.  Quistadrilus multisetosus, dorsal  pectinate chaeta.
Fig. 8.  Q. multisetosus, posterior ventral  chaeta.
Fig. 9.  Ij. multisetosus:  (a) anterior ventral  chaeta;  (b)  posterior
         ventral chaeta.
                                    14

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6(4)  Dorsal fascicles composed of capilliform and distinctly pectinate
          chaetae (Fig. 10)	  Spirosperma ferox

      Dorsal fascicles composed of capilliform chaetae and other shorter,
          much thinner capilliform-like chaetae, which may have pectinate
          tips, but are difficult to differentiate	7

7(6)  All anterior ventral chaetae bifurcate, 2 per fascicle, teeth
          small (Fig. lla).  Posterior ventral  chaetae 1 per fascicle,
          distal tooth reduced or rudimentary (Fig. lib).  Lake Tahoe.  .  .
          	  Spirosperma beetoni

      Anterior ventral fascicles contain at least some simple-pointed
          chaetae	8
                                    lla
lib
Fig. 10.  Spirosperma ferox,  dorsal  pectinate  chaeta.
Fig. 11.  J5. beetoni:  (a)  anterior  ventral  chaeta;  (b)  posterior  ventral
          chaeta.
                                    15

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B(7)  Ventral fascicles of segments II, III and often segment IV include
          1 to 3 simple-pointed crotchet chaetae and 1 to 3 bifurcate
          chaetae.  Posterior ventral  chaetae with teeth subequal or
          distal tooth longer than proximal tooth (Fig. 12)	
          	 . 	 Spirosperma nikolskyi

      Ventral fascicles of segments II-VIII or IX composed of 1
          simple and 1 bifurcate crotchet chaeta.  Posterior ventral
          chaetae 1 per fascicle, strongly recurved with thin distal tooth
          (Fig. 13)	Spirosperma carolinensis

9(3)  Segment I with large mouth and enlarged eversible pharynx
          (Fig. 14). Dorsal and ventral chaetae of segment II usually
          single with short, thin distal tooth; chaetae of segment  II and
          often segment IV lacking.  Posteriad, dorsal fascicles composed
          of capilliform and bifurcate crotchet chaetae with distal tooth
          thinner but about as long as proximal tooth	
          	 Ilyodrilus mastix
      Segment I with normal mouth, without an enlarged eversible
          pharynx, anterior dorsal and ventral chaetae other than above.
                                                                         10
        12
13
Fig. 12.  Spirosperma nikolskyi,  posterior ventral  chaetae.
Fig. 13.  S. carolinensis, posterior ventral  chaeta.
Fig. 14.  Tlyodrilus mastix, anterior end illustrating enlarged mouth.
                                     16

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10(9)   Anterior dorsal  fascicles composed of capilliform and bifurcate
            crotchet chaetae (Figs.  15, 16a, 17, 18, 19a) without
            intermediate teeth	11

        Anterior dorsal  fascicles composed of capi111 form and pectinate
            chaetae (Figs.  20, 21a,  29).  [Intermediate teeth of pectinate
            chaetae may  require approximately 1000X magnification to be
            observed.]   	16

11(10)  Dorsal crotchet  chaetae from approximately segment VII posteriad
            modified to  a spatulate  shape when viewed In facial  aspect
            (Fig. 15a) and  appearing compressed when viewed from lateral
            aspect (Fig. 15b)	Aulodrilus pigueti

        Dorsal crotchet  chaetae not  modified into a spatulate form as
            above	12

12(11)  Anterior ventral crotchet chaetae with greatly reduced distal
            teeth, essentially simple-pointed.  Each posterior segment
            bearing dorsal  and ventral  gill  filaments (Fig. 3)	
            	 Branchiura sowerbyi

        Anterior ventral crotchet chaetae distinctly bifurcate (although
            distal tooth nay be reduced), ^r if ventral fascicles contain
            simple crotchet chaetae, then no gill  filaments on posterior
            segments	13
                      a                               b

Fig. 15.  Aulodrilus  pigueti, posterior dorsal crotchet chaeta:  (a)
          facial aspect;  (b) lateral aspect.
                                     17

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13(12)  Teeth of anterior dorsal  crotchet chaetae equal  in length,
            somewhat ovate and not strongly divergent (Fig.  16a).
            Anterior capilliform  and crotchet chaetae appear bent  to
            nearly sigmoid in shape or form (Fig. 16a).   Mature specimens
            with spermathecal chaetae in ventral  fascicles of segment X
            (Fig. 16b)	Potamothrix vejdovskyi

        Teeth of anterior dorsal  crotchet chaetae unequal  in length  (Figs.
            17, 18a), or if teeth are similar in  length, then strongly
            divergent (Fig. 19a)	  14

14(13)  Dorsal  fascicles with 1-2 capilliform chaetae, 2-3 bifurcate
            crotchet chaetae with distal tooth shorter and thinner than
            proximal tooth (Fig.  17). Ventral fascicles  with up to 4
            chaetae, either simple-pointed or with distal  tooth shorter
            and thinner than proximal tooth.   With coelomocytes.  Lake
            Tahoe	Rhyacodrilus brevidentatus

        Dorsal  fascicles not as above, ventral  crotchet  chaetae never
            simple-pointed	15
                   16 a
16 b
17
Fig. 16.   Potamothrix  vejdovskyi:   (a) anterior dorsal crotchet, and
           capilliform  chaetae;  (b)  spermathecal chaeta.
Fig. 17.   Rhyacodrilus brevidentatus, dorsal crotchet chaeta.
                                    18

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15(14)  Distal  tooth of ventral  crotchet chaetae in segment VIII
            distinctly shorter and/or thinner than proximal tooth (Fig.
            18a).   Dorsal  crotchet chaetae also with distal tooth shorter
            and thinner than proximal  tooth,  occasionally dorsal crotchet
            chaetae may be minutely pectinate (Fig. 18b).  Capilliform and
            crotchet chaetae somewhat arcuate or sigmoid	
            	Aulodrilus pluriseta

        Distal  tooth of ventral  crotchet chaetae in segment VIII neither
            shorter nor obviously thinner than proximal  tooth.   Distal
            tooth  of dorsals equal to or slightly longer than proximal
            tooth  (Fig. 19a).  Mature specimens with several  simple-
            pointed penial chaetae (Fig. 19b).  With coelomocytes	
            	  Rhyacodrilus coccineus
      18 a
18 b
19 a
19 b
Fig. 18.  Aulodrilus pluriseta:  (a) ventral crotchet chaeta; (b)
          dorsal pectinate chaeta.
Fig. 19.  Rhyacpdrilus coccineus:  (a) dorsal  crotchet chaeta; (b)
          penial chaetae.
                                    19

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16(10)  Anterior dorsal  fascicles with broadly expanded pectinate crotchet
            chaetae (Fig.  20)	   Psammoryctides barbatus

        Anterior dorsal  fascicles with unexpended pectinate crotchet
            chaetae (Figs.  21 a, 29)	17
                                                    
17(16)  Teeth of anterior  dorsal  pectinate chaetae  long, distal  tooth
            often much longer than proximal  tooth (Fig. 21a).   Capilliform
            chaetae in segment II frequently much longer than  poster!ad.
            Anterior ventral  crotchet chaetae with  distal  tooth  1 1/2
            times longer than proximal tooth (Fig.  21b).  With
            coelomocytes	Rhyacodrilus montana

        Distal  tooth of anterior  dorsal  pectinate chaetae not  distinctly
            longer than proximal  tooth.   Capilliform chaetae,in  segment II
            not distinctly  longer than poster!ad and ventral chaetae may
            or may not be  pectinate	18
              20
21 a
21 b
Fig. 20.  Psammoryctldes barbatus, pectinate anterior dorsal crotchet
           chaeta.
F1g. 21.  Rhyacodrilus montana;  (a) anterior dorsal pectinate chaeta;
          (b) anterior ventral crotchet chaeta.
                                     20

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18(17)  Posterior dorsal and ventral fascicles containing strongly
            sigmoid, arcuate crotchet chaetae (Fig. 22)	
            	Tubifex hartnani

        Posterior dorsal and ventral fascicles containing no strongly
            sigmoid or arcuate crotchet chaetae	19

19(18)  Anterior and posterior ventral chaetae pectinate (Fig. 23).  With
            coelomocytes.  Lake Superior	
             	 Rhyacodrilus punctatus
        Anterior and posterior ventral chaetae not pectinate.
                   20
                      22
23
Fig. 22.  Tubifex harmani, posterior dorsal crotchet chaeta.
Fig- 23.  Rhyacodrilus punctatus. anterior ventral chaeta.
                                     21

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20(1P)  Capilliform chaetae very long and thin, poster!ad from segment X
            capilliform chaetae 2-3 times longer than diameter of
            respective segment.  Long thin worms	Tubifex ignotus

        Capilliform chaetae not especially long and thin and progressively
            diminish in length posteriad to segment X	 21

21(20)  Anterior ventral  chaetae with distal  tooth approximately twice as
            long as reduced proximal  tooth (Fig. 24)	
            	 Tubifex nerthus

        Teeth of anterior ventral  chaetae not as above.  [Henceforth
            specimens must have attained sexual maturity in order to be
            identifiable to species,  otherwise specimens can be
            categorized only as "Unidentifiable immature Tubificidae with
            capilliform chaetae"]	22
Fig. 24.  Tubifex nerthus, anterior ventral chaeta.
                                    22

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22(21)   Mature individuals bear a muscular penial  bulb attached to a
            crescent-shaped atrium which constricts into very long
            annulated vas deferens (Fig. 25).   Penis sheath a granular
            membrane, very thin-walled and often indistinct.   No modified
            genital  chaetae present	Tubifex tubifex

        Penial apparatus, atrium and vas deferens  not as above.
            Individuals bear a translucent penis sheath and/or modified
            genital  chaetae in at least one segment between segments VII
            and XI	23
 Penis Bulb
Vas Deferens
                                            Penis Sheath
   Fig. 25.  Tubifex tubifex, penis bulb, atrium, and vas deferens.
23(22)  Mature individuals bear a short, broad penis sheath in segment
            XI (Fig.  26a).  Penial  and spermathecal  chaetae long,  thin,
            parallel-sided (Fig. 26b,c), originating in glandular  sacs.  .
            	 Haber cf.  speciosus

        Mature individuals bear either a penis sheath or spermathecal  or
            penial  chaetae but no combination of a penTs sheath and both
            spermathecal  and penial  chaetae 	   24
                                     23

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26 a
26 b
26 c
   Fig. 26.  Haber cf. speclosus;  (a) penis sheath; (b) penial chaeta; (c)
             spermathecal chaeta.
   Fig. 71.  Potamothrix bedoti, specialized chaeta.
   24(23)   With or without a cuticular penis sheath.   Specialized genital
               chaetae present in one or more segments ranging between
               segments VII and XI	25

           With a translucent cuticular penis sheath  in segment XI.   No
               genital  chaetae in segment X.  Ventral  chaetae in segment XI
               similar in size and shape to somatic chaetae, or at most, only
               slightly thickened	32

   25(24)   Seal pel-shaped specialized chaetae (Fig. 27) present in any or- all
               segments ranging between segments VII  and XI	
               	   Potamothrix bedoti

           Genital  chaetae present only in segment X  or XI  and not seal pel -
               shaped	26

   26(25)   With penial  chaetae in segment XI, without spermathecal
               chaetae in segment X	27

           Without penial chaetae in segment XI, with spermathecal chaetae
               in segment X	29
                                       24

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27(26)  Penial chaetae enlarged with  bifurcate  tip  (Fig.  28).   Penis  sheath
            tub-shaped,  indistinct.   Pectinate  chaetae  range  from  bearing
            parallel lateral teeth to slightly  palmate  and  sigmoid with
            distal tooth  thinner  and  slightly longer  than proximal  tooth.
            Posterior dorsal fascicles consist  only of  bifurcate crotchet
            chaetae, no  capilliform chaetae.  Without coelomocytes.   .  .  .
            	   Psammoryctides minutus
        Penial chaetae  blunt-tipped  and  simple-pointed  (Fig.  19b);  no
            penis sheath, chaetae  not  as above.  With coelomocytes.  .
                                                                 28
 28(27)
Teeth of dorsal crotchet chaetae long, thin, and parallel,
    intermediate teeth fine (Fig 29).  Frequently, distal tooth of
    dorsal chaetae in segments VIII and IX twice the length of
    proximal tooth	Rhyacodrilus soda!i s

Teeth of dorsal crotchet chaetae not long and parallel and distal
    tooth of dorsal chaetae in segments VIII and IX not twice the
    length of proximal tooth	Rhyacodrilus coccineus
29(26)
Spermathecal chaetae in segment X parallel sided with teeth
    fused forming a groove (Figs. 30, 31)	
        Spermathecal chaetae not parallel  sided,  but  are  elongate
            spade-shaped, broadest  near the middle  and  tapering  to  a
            pointed tip  (Figs.  32,  33)	
                                                                          30
                                                                 31
                 28
                                       29
Fig. 28.  Psamnioryctides minutus, penial chaeta.
Fig. 29.  Rhyacodrilus soda!is, dorsal pectinate chaeta.
                                     25

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30(29)  Anterior ventral chaetae with teeth subequal or distal tooth
            slightly longer than proximal tooth.  Posteriad, ventral
            chaetae thicker, often with distal tooth more than two times
            longer than proximal tooth.  Penis sheath indistinct, if
            visible, tub-shaped with reflexed head	
            	 Psammoryctides convolutus

        Anterior ventral chaetae with distal tooth longer and thinner than
            proximal tooth, posteriad, ventral chaetae slightly shorter,
            but also with distal tooth longer and thinner than proximal
            tooth.  Penis sheath indistinct, tub-shaped but without
            reflexed head	Psammoryctides caliform'anus

31(29)  Spermathecal chaetae in segment X often two per fascicle, much
            longer than wide (Fig. 32).  [See annotations.]	
            	  Potamothrix hammoniensis

        Spermathecal chaetae in segment X usually single, short and
            broad (Fig. 33) 	 Potamothrix bavaricus
           30
31
32
33
Fig. 30.  Psammoryctides convolutus, spermathecal chaeta.
Fig. 31.  P. californlanus, spermathecal chaeta.
Fig. 32.  Tbtaniothrlx hammoniensls, spermathecal chaeta.
Fig. 33.  P. bavarfcus, spermathecal chaeta.
                                     26

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32(24)  Penis sheath well  developed, cylindrical, conical or conical
            with an elongate tip.  (Figs. 34-37)	33

        Penis sheath indistinct or short and tub-shaped (Fig. 38). . . . 36

33(32)  Penis sheath only slightly longer than wide (Fig. 34a,b).  Ventral
            chaetae of segment XI similar in shape to those in adjacent
            segments but slightly thicker	Varichaeta pacifica

        Penis sheath other than above.  Ventral chaetae of segment XI
            similar in shape, size and thickness to those in adjacent
            segments	34

34(33)  Penis sheath a cylindrical tube with a reflexed basal portion
            (Fig. 35)	  Tubifex superiorensis

        Penis sheath other than above	35
                                     35

Fig. 34.  Varichaeta pacifica:  (a) penis sheath inverted;  (b) penis
          sheath everted.
Fig. 35.  Tubifex superiorensis. penis sheath.
                                    27

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35(34)  Penis sheath conical, uniformly tapered from base to apex
             (Fig. 36a,b)	Ilyodrilus templetoni

        Penis sheath with a conical base abruptly tapered to an elongate
            apex (Fig. 37)	 Tubifex kessleri americanus

36(32)  Penis sheath tub-shaped (Fig. 38), spermatozeugmata "frying pan"
            shaped	Ilyodrilus frantzi form capillatus
        Penis sheath indistinct, delicate.  Lake Tahoe.
                                                        Varichaeta nevadana
            36 a
36 b
37
                                     38

Fig. 36.  Ilyodrilus templetoni:   (a)  penis  sheath  with  distal  end absent;
          (b) penis sheath with distal end present.
Fig. 37.  Tubifex kessleri americanus, penis sheath.
Fig. 38.  Ilyodril'us frantzi  form  ca"p"illatus,  penis  sheath.

                                     28

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37(1)   All chaetae anterior to approximately segment VII simple to
            minutely bifurcate with much reduced distal tooth (Fig.
            39a,b)	38

        Anterior chaetae never simple, teeth distinct	39

38(37)  Anterior chaetae simple.  Posteriad from approximately segment
            VII, dorsal chaetae laterally expanded with several  minute
            teeth (Fig. 40)	  Aulodrilus americanus

        Anterior chaetae appear simple (Fig. 39a) to minutely bifurcate
            with minute distal tooth.  Posteriad, dorsal chaetae bifurcate
            with reduced distal tooth (Fig. 39b)	
            	  Telmatodrilus vejdovskyi
         39 3
                                  39  b
Fi9- 39.

Fig. 40.
          Telmatodrilus  vejdovskyi;   (a)  anterior ventral  chaeta;
          (b)  posterior  ventral  chaeta.
          Aulodrilus  americanus,  posterior dorsal  crotchet chaeta.
                                    29

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39(37)  Posteriad from approximately segment VII dorsal crotchet chaetae
            spatulate when viewed from facial aspect (Fig. 41a); viewed
            laterally, each chaeta appears compressed with tiny teeth
            (Fig. 41 b)	Aulodrilus limnobius

        Posteriad from approximately segment VII dorsal chaeta not
            laterally expanded, teeth not reduced	40

40(39)  All chaetae similar; bifurcate crotchet chaetae with distal tooth
            thinner and shorter than proximal tooth (Fig. 42), anteriorly
            3-4 per fascicle, 2 per fascicle posteriad.  With
            coelomocytes	Monopylephorus he! obi us

        All crotchet chaetae not similar, or of different form and number
            than above	41
                                     b
Fig. 41.  Aulodrllus  limnobius, posterior dorsal crotchet chaeta:
          facial aspect;  (b) lateral aspect.
Fig. 42.  Monopylephorus  he!obi us, crotchet chaeta.
(a)
                                     30

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41(40)  Prostomium with a ciliated sensory cavity with an irregular opening
            on the dorsal surface of the prostomium  (Fig. 43).  Viewed
            laterally, the cavity appears as a depression and specialized
            cells lining the pit are apparent.  Chaetae of anterior
            segments II to approximately IX generally 3-4 per fascicle
            (Fig. 44a) and often thinner than those  posteriad.  Posterior
            chaetae usually number tv/o per fascicle, thicker than anterior
            chaetae (Fig. 44b).  Mature individuals  bear hook-shaped
            penial chaetae in segment XI (Fig. 44c).  With coelomocytes. .
            	 Bothrioneurum vejdovskyanum
        Prostomium without a sensory cavity, chaetae other than above.
                                                                         42
Fig. 43.  Bothrioneurum vejdovskyanum, SEM of prostomium showing sensory
          cavity (from Chapman, 1979).
Fig. 44.  B. vejdovskyanum;  (a) ventral crotchet chaeta of segment II;
          Tb) ventral crotchet chaeta of segment XXX; (c) penial chaeta.
                                    31

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42(^1)  Dorsal  crotchet chaetae posteriad from approximately segment XX
            sharply arcuate and larger than opposing ventral chaetae (Fig.
            45).   Mature individuals bear short,  thin,  parallel-sided
            spermathecal chaetae in segment X	
            	  Isochaetides curvisetosus

        Dorsal  crotchet chaetae posteriad from approximately segment XX
            neither sharply arcuate nor larger than opposing ventral
            chaetae	43

43(42)  Distal  tooth of ventral chaetae in segments II  through IV longer
            than  proximal  tooth and deflected at  an angle of approximately
            90 to axis of chaetae (Fig.  46a,b,c)	
            	 Limnodrilus udekemianus

        Distal  tooth of ventral chaetae in segments II  through IV not
            deflected 90 to axis of the chaetae.   [Henceforth specimens
            must be sexually mature to be identifiable  to species,
            otherwise specimens must be classified as "Unidentifiable
            immature Tubificidae without capilliform chaetae"]	  44
                               46a
46 b
415 c
 Fig.  45.   Isochaetides  curvisetosus, posterior dorsal chaeta.
 Fig.  46.   LimnpdriluT'udekemianus;   (a,b,c)  ventral chaetae  in  segment
          II,  illustrating  variation  in  shape.
                                     32

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44(43)  With pern's sheath in segment XI (Fig.  47a), and spermathecal
            chaetae long thin, parallel-sided  (Fig. 47b) in segment X.  .  .
            	  Isochaetides freyi

        With spermathecal chaetae in segment X and/or penial chaetae in
            segment XI or penis sheath but no  combination of genital
            chaetae and a penis sheath	45

45(44)  Genital  chaetae in segments IX and XI; spatulate and single
            in segment IX (rarely segment X) (Fig.  48a), 4-5 knobbed
            chaetae in segment XI (Fig. 48b).   With coelomocytes.    . . .
            	 Rhizodrilus lacteus

        Spermathecal  chaetae in segment X r penial chaetae
            in segment XI but both spermathecal  and pem'al  chaetae not
            present.   Penis sheaths present or absent	46
          47 a
47 b
48 a
48 b
Fig. 47.  Isochaetides freyi;  (a) penis sheath; (b) spermathecal chaeta.
Fig. 48.  Rhizodrllus lacteus;  (a) specialized chaeta in segment IX; (b)
          specialized chaetae in segment XI.
                                    33

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46(45)  With penis sheaths	49

        Without penis sheaths	47

47(46)  With penial  chaetae in segment XI, no spermathecal chaetae in
            segment X	48

        Spermathecal  chaetae present in segment X (Fig. 49a), and eversible
            penes present in segment XI (Figs 49b,c)	
            	  Potamothrix moldaviensis
                               b
Fig. 49.  Potamothrix moldaviensis:  (a) spermathecal chaeta; (b)
          partially everted penis; (c) fully everted penis.
                                    34

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48(47)  Pem'al chaetae in segment XI simple-pointed, distally hooked
            (Fig. 50).  Lake Superior	Phallodrilus hallae

        Penial chaetae in segment XI sickle-shaped, twice as long and much
            thicker than somatic chaetae (Fig. 51a,b).  With coelomocytes.
            	Rhyacodri1 us falci f omri s

49(46)  Penis sheath tub-shaped (Fig. 38).   Spermatozeugmata "frying pan"
            shaped, distal  tooth of anterior chaetae longer than proximal
            tooth	Ilyodrilus frantzi

        Penis sheath elongate and cylindrical	50
                50
51 a
51 b
Fig. 50.  Phallodrilus hallae, penial chaeta.
Fig. 51.  RhyacodriTu? falciformis, penial chaeta:
          (b) facial aspect.
          (a)  lateral  aspect;
                                    35

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50(49)  Margin of head of penis sheath set at essentially right angles to
        axis of shaft (Figs.  52-57)	51

        Margin of head of penis sheath slanted, hooded or otherwise, not
        at right angles to axis of shaft (Figs. 58-64)	56

51(50)  Penis sheath reddish-brown; with two tapered lateral
            projections (Fig.  52)	Limnodrilus rubripenis

        Penis sheath clear; distal  end without two tapered lateral
            projections	 52

52(51)  Distal 3/4 of penis sheath cylindrical, tube-like, basal 1/4
            conical, shaft long in fully developed sheaths (Fig. 53). . .
            	  Limnodrilus angustipenis

        Penis sheath not distinctly differentiated into cylindrical
            distal and conical  basal portions, shaft short or long in
            fully developed sheaths	53

53(52)  Fully developed sheaths long (generally greater than 300 urn), shaft
            uniformly cylindrical with head a round plate set at right
            angles to shaft.   Margin of head may be slightly up-turned on
            one side (Fig. 54)	
            	Limnodrilus hoffmeisteri (spiralis form)

        Fully developed sheaths short, head of sheath other than above. .
               	54

54(53)  Shaft broadly expanded basally, head a round plate (Fig. 55)
            	  Limnodrilus psamnophilus

        Shaft not broadly expanded nasally, head of sheath other than
            above	55

55(54)  Anterior ventral chaetae of segment II to approximately segment
            IV with distal tooth longer than proximal tooth and bent at a
            90 angle to axis of chaetae (Figs. 46a,b,c).  Penis sheath
            with a round reflexed head (Fig. 56)	
            	 Limnodrilus udekemianus

        Anterior ventral chaetae with distal tooth subequal or only
            slightly longer than proximal tooth and teeth set at 45 or
            less to axis of shaft.  Shaft of sheath thin, head small  (Fig.
            57)	Limnodrilus profundicola

56(50)  Mature shaft short, head of sheath spade-shaped (Fig. 58).
            	 Limnodrilus silvani

        Mature shaft long, (generally greater than 300 urn) and
            head of sheath not spade-shaped	57
                                     36

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     52
                             53
 55
                             56
                                                 57
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
52.
53.
54.
55.
56.
57.
Limnodrilus rubripenis,  penis  sheath.
L. angustTpenis, penis  sheath.
r. hotfmeisteri  (spiralis  form).
U. psammophilus, penis  sheath.
L. udekemianus,  penis sheath.
L_. profundicoTa, penis  sheath.
penis sheath.
                                     37

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57(56)  Head of penis sheath with margin scalloped (Fig. 59a), or
            scalloped with an irregular distal  projection (Fig., 59b) .  .  .
            	 Limnodrilus hoffmeisteri (variant form)

        Head of penis sheath not scalloped	  58

58(57)  Shaft wall  not excessively thickened (Figs. 60, 61) 	  59

        Shaft noticeably thick-walled (Figs. 62-64) perhaps appearing
            as two layers	60

59(58)  Head of penis sheath with an overhanging hood and a broad, flat
            proximal  lip, distally the diameter of the shaft flares into
            the head; mature tube length 300-600 urn (Fig. 60)	
            	   Limnodrilus hoffmeisteri

        Head of penis sheath without an overhanging hood.  Shaft
            slender,  long (600-700 urn) sigmoid with head equilaterally
            triangular and hence bilaterally symmetrical (Fig. 61). ...
            	  Limnodrilus claparedianus

60(58)  Head of penis sheath broad, asymmetrically triangular and distal
            end of shaft canted (Fig. 62)	  Limnodrilus maumeensis

        Head of penis sheath longer than wide,  shaft not canted
            distally	61

61(60)  Head of penis sheath small, pear-shaped, bilaterally
            symmetrical, apical portion of head often reflexed over
            orifice,  lower proximal portion small  (Fig. 63)	
            	Limnodri1us cervix (variant form)

        Head of penis sheath asymmetrical, with an offset proximal
            digitate  lobe (Fig. 64)	Limnodrilus cervix
                                    38

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58
                                         59 b
61
63
Fig. 58.  Limnodrilus silvani, penis sheath.
Fig. 59.  L. hoffmeTsteri (variant form), illustrating two penis sheath
          types!(a) scalloped margin; (b) scalloped margin with
          irregular distal projection.
Fig. 60.  L. hoffmeisteri, penis sheath.
Fig. 61.  r. claparedianus, penis sheath.
Fig. 62.  r. maumeensis, penis sheath.
Fig. 63.  r. cervix (variant form), penis sheath.
Fig. 64.  U. cervix, penis sheath.
                                     39

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                                 SECTION 5

                                 GLOSSARY*


Anteriad:  Direction toward the anterior of an organism.

Arcuate;  Curved or shaped like a bow.

Bifurcate:  A condition of a chaeta where its apex is cleft, forming two
unequal teeth.

Capi11iform Chaeta:  A dorsal, uncleft, hair-like, somatic chaeta; longer
and usually more flexuous than a crotchet chaeta (sometimes called a hair
seta).

Chaeta (pi. Chaetae);  A bristle, which in various forms, aids primarily
in locomotion (somatic chaetae) or can function in connection with
reproduction (genital chaetae).  (In the literature, "seta" is frequently
used instead of "chaeta," but here the former term is reserved for its
application in arthropod morphology).

C1itel1 urn;  A differentiation of the epidermis in the genital region into
a somewhat verrucose "sleeve" which will transform into a cocoon that
serves as a repository for the eggs following their fertilization.

Coelomocyte:  Free cells within the body cavity (coelom).  Granular in
appearance, these spherical to ovoid cells may completely fill the body
cavity in certain species.  A characteristic feature in four of the North
American tubificid genera:  Bothrioneurum, Monopylephorus, Rhizodrilus,
and Rhyacodrilus.

Cosmopoliton:  World-wide in distribution.

Crotchet chaeta (pi. Chaetae);  A somatic chaeta sometimes simple, but
usually bifurcate, with two primary lateral teeth, with or without
intermediate teeth between the lateral teeth.  Generally refers to simple
or bifurcate chaetae without intermediate teeth.  See also Pectinate
Chaeta.
*Additional  morphological  terms applied in oligochaetology can be found
in Brinkhurst and Jamieson (1971) and Reynolds (1977)
                                    41

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Fascicle:  A "cluster" or "bundle" of chaetae.  Generally four fascicles
per segment, two located dorso-laterally and two located ventro-laterally.

Genital Chaeta:  A chaeta which functions in sexual  reproduction;
spermathecal and penial chaeta.

Genital Segments;  Body segments (ordinarily segments X and XI) which
bear the reproductive organs.

Gill Filaments;  Paired finger-like extensions of the body wall that
function in respiration.  Located on the posterior segments of Branchiura
sowerbyi, two per segment, one positioned dorsally and one ventrally.

Modulus:  A knob or enlarged region on a crotchet chaeta generally
located at or near the midlength of the chaeta where it leaves the body
wal 1.

Papilla (pi. Papillae):  Projections of the dermis or body wall.
Frequently heavily cuticularized and obscured by accumulated foreign
particles, thereby giving the worm a very opaque appearance.

Pectinate Chaeta:  A crotchet chaeta generally equipped with two primary
lateral teeth and few to several finer intermediate teeth.  Nearly always
dorsal  and in fascicles with capilliform chaetae.  Intermediate teeth may
require 1000X magnification to be resolved.

Penial  Chaeta;  A chaeta associated with the penes occurring in the
ventral fascicles of Segment XI, ordinarily their shape and size is
unlike  that of the somatic chaetae.

Penis Sheath;  A translucent cuticular covering of the penis in segment
XI, ranging from a thin, often obscure ring to an elaborate, thick tube.

Posteriad:  Direction toward the posterior of an organism.

Prostomium:  The anterodorsal part of the cephalic segment (Segment I).

Segments:  A series of anatomical divisions of the body (somites or
compartments), each usually separated from its neighbor by a septum
(partition).

Seta (pi. Setae);  See Chaeta.

Simple  Chaeta;  A chaeta with an uncleft apex.

Somatic Chaeta:  A chaeta which functions in connection with locomotion;
the somatic segments only, as opposed to specialized genital chaetae that
are associated with the genital segments.
                                     42

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Spermathecal Chaeta;  Chaeta associated with the spermatheca, generally
in the ventral fascicles of Segment X.  A characteristic feature of
certain genera and species, their shape is usually unlike that of a
somatic chaeta.

Spermatozeugma (pi. Spermatozeugmata);  Organized bundles of sperm found
in the atrium prior to copulation and in the spermatheca following
copulation.  Of various, often diagnostic shapes and sizes, but generally
with an inner lumen surrounded with sperm heads oriented inward and sperm
tails radiating outward.
                                    43

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                                 SECTION 6

                                ANNOTATIONS
1.    Aulodrilus americanus

     Largest species of the genus.   Reproduces primarily by budding and
     fragmentation.  Moderately tolerant to organic enrichment and common
     in productive habitats.   Dwells in tubes that often stay with the
     individual after sieving.  Nearctic.  Known from St. Lawrence Great
     Lakes, the eastern United States, Cayuga Lake, New York, British
     Columbia, Manitoba, New Brunswick, Northwest Territories, Ontario,
     Quebec, and Saskatchewan.

2.    Aulodrilus limnobius

     Exhibits a preferance for silty substrates in mesotrophic habitats.
     Moderately tolerant organism that reproduces primarily by budding
     and fragmentation.  Often collected within a tube of agglutinated
     organic materials.  The species is often represented in the drift of
     rivers.  Usually sympatric with . pigueti.  Cosmopolitan.
     Widespread in the United States.  Reported from Alabama, Louisiana,
     North Carolina, South Carolina, Tennessee, Wisconsin, and Canada.

3.    Aulodrilus pigueti

     Usually sympatric with A. limnobius and with a similar distribution,
     life history and habitat preferences.  Cosmopolitan.

4.    Aulodrilus pluriseta

     Locally abundant in enriched habitats in silty substrates.  Forms a
     mucoid tube similar to other members of the genus.  Reproduces
     sexually and asexually by budding.  Cosmopolitan.  In North America,
     reported from St. Lawrence Great Lakes, Illinois, Indiana, Cayuga
     Lake, New York, North Carolina, Pennsylvania, Tennessee, Hudson
     River, Ohio River, Wisconsin River drainage, and British Columbia,
     Quebec in Canada.

5.    Bothrioneurum vejdovskyanum

     A widespread species.  Generally most abundant in large rivers in
     coarse sand substrates.  Rarely abundant in lentic habitats.  Has
     likely been frequently overlooked in many North American collections
     due to confusion regarding the characteristic sensory prostomial pit


                                     44

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     and infrequent occurrence of sexually mature individuals within a
     population.  Cosmopolitan.  Known from St. Lawrence Great Lakes,
     Indiana, Illinois River, Cayuga Lake, New York, Ohio River,
     Wisconsin River, Lake Washington, British Columbia and Quebec.
     Note;  M.S. Loden (Personal Communication, 1981) reported^.
     americanum from Georgia and Louisiana.  In the immature state, it is
     indistinguishable from EL vejdovskyanum and mature specimens lack
     penial chaetae.

6.   Branchiura sowerbyi

     Large worms that are rarely abundant.  Known to thrive in heated
     effluents in Europe.  Great Lakes records are from Lake St. Clair to
     Lake Erie.  Frequently fragments.  Cosmopolitan.  Widespread
     throughout North America, generally in rivers.

7.   Haher cf. speciosus

     Only two recorded specimens in North America; Susquehanna River, New
     York, and Hudson River, New York.

8.   Ilyodrilus frantzi and Ilyodrilus frantzi form capillatus

     Ilyodrilus frantzi was originally described by Brinkhurst (1965)
     from Suisan Bay, California.  The species was redescribed to include
     l_. frantzi form capillatus by the same author in 1978, based upon
     specimens collected  in the Fraser River, British Columbia.  No other
     known distributional records.

9.   Ilyodrilus mastix

     Recently described by Brinkhurst (1978) from the Fraser River,
     British Columbia, the only known North America record.

10.  Ilyodrilus tempi etoni

     Common in both lake  and river habitats, attaining greatest densities
     in enriched habitats.  One of the most common tubiflclds in North
     America.  Often sympatric with Limnodrilus hoffmeisteri in highly
     enriched waters.  Easily confused with Tubifex tubifex.  Holarctic.
     Widely distributed throughout the United States and is probably
     widespread in Canada.

11.  Isochaetides curvisetosus

     Transferred from Peloscolex by Brinkhust (1981).  An occasional
     species apparently not occurring in eutrophic habitats.  Nearctic.
     Known from St.  Lawrence Great Lakes, Alabama, Indiana, North
     Carolina, and Pennsylvania.
                                     45

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12.  Isochaetides freyi

     Transferred from Peloscolex by Brinkhurst (1981).  An occasional
     species generally occurring only in mesotrophic habitats.  Rarely
     very abundant.  Nearctic.  Known from St. Lawrence Great Lakes,
     Mississippi River, Alabama, Indiana, Louisiana, Cayuga Lake, New
     York, North Carolina, Pennsylvania, Tennessee, Chippewa River and
     Red Cedar River in Wisconsin, Manitoba and Fraser River, British
     Columbia, Canada.

13.  Limnodrilus angustipenis

     An uncommon taxon usually collected in oligotrophic lakes.
     Nearctic.  Known from St. Lawrence Great Lakes, Alabama, Louisiana,
     North Carolina, Tennessee, New Brunswick, Ontario, and Manitoba.

14.  Limnodrilus cervix and Limnodrilus cervix (variant form)

     The distinction between the typical and variant forms was first
     noted by Hiltunen (1969).  The taxonomic status of the variant form
     is a subject that has, to date, not been adequately resolved, and a
     state of confusion exists as to the correct rank of the variant
     form.  In this treatment, the authors defer from making a taxonomic
     decision as to the status of variant forms, whether a subspecies,
     ecomorph, hybrid or other entity, but have maintained the variant
     form herein based upon apparent distributional discontinuities
     between the typical and variant forms in relation to habitat and
     water quality.  The typical form is common, although rarely
     abundant, through large areas of the United States.  It is often
     common in productive, enriched habitats, although it occurs
     infrequently in grossly degraded situations.  In contrast, the
     variant form has been collected primarily in areas sustaining high
     degrees of enrichment or in grossly polluted lakes, rivers and
     harbors in the United States.  It is often one of the predominant
     tubificids, attaining large population densities in such
     situations.  In such cases, the variant form has been collected both
     sympatric with, and in the absence of typical  form.  Hoi arctic.
     Widespread throughout the United States, including the St. Lawrence
     Great Lakes, Mississippi River, Illinois River, Ohio River, Hudson
     River, and known from Ontario, Canada.

15.  Limnodrilus claparedianus

     A common species in both lakes and rivers.  Generally most abundant
     in enriched habitats but also known from clean water areas.
     Cosmopolitan.  Recorded from throughout the United States and Canada.

16.  Limnodrilus hoffmeisteri
     A ubiquitous species that is probably the most abundant and
     widespread species in North America.   Known from habitats ranging
     from pristine to grossly polluted.   An extremely tolerant species

                                     46

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     that is frequently the most abundant organism in areas  sustaining
     high degrees of organic enrichment.  Several forms exist.  See U
     hoffmeisteri (variant form) and L_. hoffmeisteri (spiralis form).
     Cosmopolitan.  Widely reported in the United States and Canada.

17.  Limnodrilus hoffmeisteri (spiralis form)

     This form was first noted by Hiltunen (1967) in the Great Lakes and
     applies to individuals possessing a penis sheath with a flat,
     rounded head set perpendicular to the long axis of the  sheath.  The
     name spiral is is applied to individuals of this type due to their
     similarity to Eisen's (1885) Camptodrilus [aLimnodrilus] spiral is.
     The correct rank of this taxon has not been satisfactorily
     resolved.  The authors have maintained this form as a distinct taxon
     because of apparent differences in ecological requirements between
     the typical and spi rali s form.  The spi rali s form has been reported
     from a variety of habitats but is generally most abundant in grossly
     polluted habitats often attaining large population densities in the
     absence of typical L_. hof fmei steri.  Widespread?  Known from St.
     Lawrence Great Lakes, Mississippi River, Ohio River.

18.  Limnodrilus hoffmeisteri (variant form)

     Herein, this name is applied to any of several  forms that possess a
     scalloped margin on the head of the penis sheath.   The status of
     this taxon has not been satisfactorily resolved.  The authors defer
     from making a decision regarding taxonomic rank of these forms, but
     concede that the morphology of these types is likely ecologically
     related.   Several  authors make no distinction between the variant
     form and typical specimens.  In this treatment the variant form is
     maintained as a distinct taxon for two reasons:  First, the authors
     have noted a discontinuous distributional pattern between variant
     and typical forms, and secondly, the distinction is maintained in
     hopes that ongoing and future investigations will  elucidate the
     ecological  factor or factors affecting the occurrence of variant
     types.   Discontinuous distribution.  Cosmopolitan?  Known from
     Hudson River, Mississippi River, Missouri River and St. Lawrence
     Great Lakes.

19.  Limnodrilus maumeensis

     This species has been reported only from habitats  sustaining high
     degrees of organic enrichment.  Frequently very abundant in polluted
     harbors and river mouths.  Nearctic.   Known from St.  Lawrence Great
     Lakes,  Illinois River, Mississippi River, and Louisiana.


20.  Limnodrilus profundicola

     Generally restricted to cold oligotrophic habitats.   Rarely a
     dominant  species in any tubificid assemblage.   Cosmopolitan.   Known
     from St.  Lawrence  Great Lakes, Nebraska,  South  Dakota,  Wisconsin,

                                    47

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     Alberta,  British Columbia,  Manitoba,  New Brunswick, Northwest
     Territories, Ontario,  and Saskatchewan.
21.   Lirnnodrilus psammophilus
     Described by Loden (1977) from material  collected in Florida,
     Louisiana, and Tennessee.
22.   Limnodrilus rubripenis
     Described by Loden (1977) from Louisiana.  Subsequently reported by
     Wetzel  (1980) from a stream in southern  Illinois.
23.   Limnodrilus silvani
     Distributional and ecological  information sparse.  A western species
     known only from California (Brinkhurst,  1965) and one unpublished
     record from Lake Ontario at the mouth of the Niagara River.
     Hoi arctic.
24.   Limnodrilus udekemianus
     A long worm, rarely very abundant, usually littoral.  Found in
     organically polluted waters as well  as oligotrophic habitats.
     Cosmopolitan.  Widespread in United States and Canada.
25.   Monopylephorus helobius
     A coastal species described by Loden (1980) from marine, estuarine
     and freshwater habitats in the southern  United States.  Not likely
     to be collected inland from the coast.
26.   Phallodrilus hallae
     Oligotrophic waters of Lake Huron and Lake Superior.
27.   Potamothrix bavaricus
     An uncommon species generally collected in littoral habitats.
     Hoi arctic.  Known from several localities in North America, ranging
     from Lake Michigan (Green Bay), Illinois, Indiana to Utah,
     California, and Oklahoma.
28.   Potamothrix bedoti
     This species, until Spencer's (1978) work, was considered a variant
     form of . bavaricus.  It appears to prefer a silty, muck, substrate
     in profundal areas of lakes.  Holarctic.  In North America known
     only from St. Lawrence Great Lakes and Cayuga Lake, New York.
                                     48

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29.   Potamothrix hammonlensis

     A common European species reported only twice in North America, from
     Green Bay, Lake Michigan and one questionable record from Ontario in
     Canada.  The authors have not been able to locate specimens
     collected in North America.  Its occurrence, although possible,
     awaits confirmation.  The figure of P. hammoniensis (Fig.  32)
     included herein was drawn based upon~~European material supplied by
     R.O. Brinkhurst.

30.   Potamothrix moldaviensis

     A common and often abundant species in mesotrophic waters of the St.
     Lawrence Great Lakes and its drainage.  Often sympatric with .
     vejdovskyi.  Hoi arctic.

31.   Potamothrix vejdovskyi

     A common and often abundant species in mesotrophic waters of the St.
     Lawrence Great Lakes and its drainage.  Often sympatric with P_.
     moldaviensis.  Hoi arctic.

32.   Psammoryctides barbatus

     Known only from Europe until reported by Vincent (1979) in the
     freshwater St. Lawrence  River upper estuary.  Hoi arctic.

33.   Psammoryctides cali form'anus

     Uncommon.  Originally described in a collection from California
     (Brinkhurst, 1965).  Has subsequently been reported from the St.
     Lawrence Great Lakes (St. Marys River), Black River, Michigan, and
     Cayuga Lake, New York.  Nearctic.

34.   Psammoryctides convolutus

     Recently described by Loden (1978) in collections from swamp
     habitats with fine organic muck substrates.  Nearctic.  Gulf Coast
     swamps from Florida to eastern Mexico.

35.   Psammoryctides minutus

     A western species known  only from Lake Tahoe in the United States and
     Sturgeon Lake in Alberta, Canada.

36.   Quistadrilus multisetosus

     Common North American species that occurs in a wide range of
     habitats but is found in greatest densities in organically enriched
     habitats.  Two subspecies, Quistadrilus multisetosus multisetosus
     and . m. longidentus originally described by Brinkhurst and Cook
     (1966), have been maintained by many investigators but have not been


                                    49

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     included here because of the questionable validity of their
     subspecific rank (Loden and Dugas, 1978).  Specimens with anterior
     and posterior ventral chaetae of similar shape are referable to Q.
     m. longidentus; those with posterior ventral chaetae bearing reduced
     distal teeth are referable to (). m. multisetosus.  Nearctic.  Known
     from the St. Lawrence Great Lakes, Mississippi River, Ohio River,
     Wisconsin and throughout the eastern United States.

37.  Rhizodrilus lacteus

     This nearctic species is rare in North America, known only from
     Illinois and South Carolina.

38.  Rhyacodrilus brevidentatus

     Endemic to Lake Tahoe; not likely to be found elsewhere.

39.  Rhyacodrilus coccineus

     An occasional species, never very abundant.  Ecological requirements
     poorly known.  Cosmopolitan.  In North America known from the St.
     Lawrence Great Lakes and its drainage and the Wisconsin River.

40.  Rhyacodrilus falciformis

     Small  worms, ecology poorly known.  Until recently, reported only
     from Europe.  Only one United States record; from Hudson River, New
     York.   In Canada, four specimens reported from Airport Creek,
     Victoria, British Columbia.

41.  Rhyacodrilus montana

     An uncommon species generally found only in cold oligotrophic and
     profundal habitats.  Nearctic.  In North America, known from the St.
     Lawrence Great Lakes and its tributaries, British Columbia, Manitoba,
     Northwest Territories, and Saskatchewan.

42.  Rhyacodrilus punctatus

     Recently reported in Lake Superior by Cook (1975).  Prior to this
     record, the species was known only from Europe.

43.  Rhyacodrilus soda!is

     An uncommon species with extremely variable chaetal morphology that
     suggests taxonomic uncertainty.   This species needs considerable
     attention in a generic revision  to verify its correct taxonomic rank
     or position.  Environmental requirements poorly documented.
     Holarctic.   Known in the United  States from Alabama, Lake Ontario,
     Louisiana,  Tennessee, and in Canada from British Columbia, Manitoba,
     Northwest Territories, and Saskatchewan.
                                     50

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44.  Spirosperma beetoni

     Endemic to Lake Tahoe.

45.  Spirosperma carolInensis

     Known only from the southeastern United States in North Carolina.

46.  Spirosperma ferox

     A common, often abundant species in moderately enriched habitats,
     and uncommon in oligotrophic or grossly polluted areas.  Individuals
     with a non-granular epidermis occur occasionally.  Holarctic.  In
     North America patchily distributed in the Great Lakes. Louisiana,
     and eastern North America.

47.  Spirosperma nikolskyi

     Based upon a recent revision by Brinkhurst (1981), this taxon
     includes two formerly well known North American species, Peloscolex
     oregonensis and _P. variegatus (sensu Brinkhurst, 1979c).  An
     uncommon species, generally most abundant in cold, oligotrophic
     profundal habitats.  A dominant organism, abundant in oligotrophic
     profundal areas of the St. Lawrence Great Lakes.  Holarctic.  Known
     from Alabama, Alaska, Great Lakes and the type locality of P_.
     variegatus (sensu Brinkhurst, 1979c) Sckuylkill River, Pennsylvania,
     Georiga, Louisiana, Mississippi, North Carolina, Oregon, Tennessee,
     and Washington in North America.

48.  Telmatodrilus vejdovskyi

     A western species known only from California and British Columbia.

49.  Tubifex harmani

     Recently described by Loden (1979) from material collected in
     Louisiana.  Reproduces primarily by asexual  fragmentation; sexually
     mature individuals rare.  Ecological preferences undocumented.
     Nearctic.  Known only from Florida, Indiana, Lousiana, Wisconsin,
     and British Columbia.

50.  Tubifex ignotus

     An uncommon species that in North America is found primarily in
     harbors and in lakes near river mouths.   Holarctic.   In North
     America, known from Alabama,  Lake Michigan,  Lake Ontario,  and the
     St.  Marys River.

51.  Tubi fex kessleri americanus

     An uncommon subspecies found  in cold,  oligotrophic,  profundal areas.
     Known from Lake Michigan, Lake Superior, and Wisconsin in  the United

                                     51

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     States and from Alberta, New Brunswick, Northwest Terrestories,
     Ontario, Saskatchewan, and the Yukon 1n Canada.

52.   Tubifex nerthus

     Recently combined with J. newfei by Brinkhurst (1978).  A tolerant,
     coastal species known in both brackish and freshwater.  Holarctic.
     Known from Newfoundland and New Brunswick.

53.   Tubifex superiorensis

     Transferred from Peloscolex to Tubifex by Brinkhurst (1981).  A
     small worm, occasional in cool, clean waters.  Nearctic.  Known
     primarily from the Great Lakes and recently from the Mississippi
     River, Wisconsin River and Red Cedar River in Wisconsin.

54.   Tubifex tubifex

     Indifferent to water quality, locally abundant in habitats ranging
     from grossly polluted and organically enriched, to pristine alpine
     and suhalpine lakes and streams.  Often abundant in habitats
     supporting few other species in both clean and perturbed waters.
     Frequently confused with Ilyodri1us tempietoni.  Cosmopolitan.
     Widespread throughout northern North America, apparently rare in the
     southern United States.

55.   Varichaeta nevadana

     Recently transferred from Isochaeta by Brinkhurst (1981).  Endemic
     to Lake Tahoe.

56.   Varichaeta pacifica

     Described by Brinkhurst (1981) from Washington and Alaska.
     Apparently a cold stenotherm.
                                     52

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                           SELECTED BIBLIOGRAPHY
Aston, R.J.  1973.  Tubificids and water quality:  A review.  Environ.
    Pollut.  (5):1-10.

Baker, H.R., and R.O. Brinkhurst.  1981.  A revision of the genus
    Monopylephorus and redefinition of the subfamilies Rhyacodrilinae and
    Branchiurinae (Tubificidae: OUgochaeta).   Can. J. Zool. 59: 939-965.

Barbour, M. , D.6. Cook, and R. Pomerantz.  1980.   On the question of
    hybridization and variation in the oligochaete genus Limnodrilus.
    In:  R. 0.  Brinkhurst and D. G. Cook, eds.  Aquatic oligochaete
    biology.  Plenum Press, New York.  pp. 41-53.

Bass, D. , and R.C. Harrel.  1981.  Water Quality of a southeast Texas
    stream.  Hydrobiologia 76:69-79.

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Brinkhurst, R.O.  1965.  Studies on the North  American aquatic
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                                     53

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            1976.  Aquatic Oligochaeta recorded from Canada and the St.
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                                     54

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Chapman, P.M.  1979.  The prostomial pit in Bothrioneurum
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         , M.A. Parrel!, and R.O. Brinkhurst.  1982a.  Relative tolerances
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         , M.A. Parrel! , and R.O. Brinkhurst.  1982b.  Relative tolerances
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Chatarpaul , L., J.B. Robinson, and N.K. Kaushik.  1980.  Effects of
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          , and I.  Horvath.  1979.  The effects of environmental oxygen
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   	, J. Filyp, L. Molnar, and E. Nagy.  1980.  Karyometric
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                                     55

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Fleming, T. P.  1981.  The ultrastructure and hlstochemistry of the
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Goodnight, C.J.  1960.  Oligochaetes as indicators of pollution.  Proc.
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Grigelis, A.  1980.  Ecological studies of aquatic oligochaetes in the
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              1979b.  An attempt to determine the influence of the gut
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                                     56

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            1979.  Revision of the genus Peloscolex (Oligochaeta,
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_ , and M.A. Scott.  1977.  An environmental index based on
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                                     57

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                                     58

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Spencer, D.R.  1978.  The Oligochaeta of Cayuga Lake, New York with a
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                                     59

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                         INDEX TO SCIENTIFIC NAMES
americanum (Bothrioneurum), 45
americanus (Aulodrilus), 5 29,44
amerjcanu?, (TubifexT~kessleri, 7,28,
   51
angustipenis (Limnodrilus), 5,36,37,

Aulodrilus, 5
   americanus, 5,29,44
   Iimnobius7 5,30,44
   pigueti, 5,17,44
   pluriseta, 5,19,44
barbatus (Psammorycti des). 6,20,49
bavaricus (Potamothrix), 6,25,48
bedoti (Potamothrix), 6,24,48
beetoni (Spi rosperma), 7,15,51
Bothrioneurum, 5
   americamim, 45
   vejdovskyanum, 5,31,44,45
Branchiura, 5
   spwerbyi, 5,12,17,42,45
breyidentatus (Rhyacodrilus), 6,18,
   50"
cali form anus (Psammoryctides), 6,

Camptodrilus (Limnodrilus), 47
   (form spiral is), 47
capi11atus (ITyodri1 us frantzi
   form), 5,28,45
carolinensis (Spirosperma), 7,16,51
cervix (Limnpdrilus), 5,38,39,46
   ("variant form), 6,38,39,46
c1aparedianus (Limnodrilus), 6,38,

coccineus (Rhyacodrilus), 6,19,25,50
conyulutus (Psammorycti des), 6,25,

curvisetosus (Isochaetides), 5,32,45
falciformis (Rhyacodrilus), 6,35,
   50
ferox (Spirosperma), 7,15,51
form capillatus, 5,28,45
   (Ilyodrilus frantzi), 5,35,45
frantzi (Ilyodrilus), 5,35,45
   form capi11atus , 5,28,45
freyi (Isochaetides), 5,33,46
hallae TPhallpdrilus). 6,35,48
hammpni ens i s (Potamothri x), 2,25,

Haber, 5
   cf. speciosus, 5,23,24,45
harmam'ttubi f ex), 7,21,51
he!obi us (Mpnppylephorus), 6,30,48
hoffmeisteri (LimnodriTus), 6,38,39,

   (spiralis form), 6,36,37,47
   (van' ant form), 6,38,39,47
ignotus (Tubifex), 7,21,51
Ilypdrilus, 5
   frantzi', 5,35,45
      form capi11atus, 5,28,45
   mastix, 5,16,45
   tempietoni, 5,28,45,52
Isochaeta, 52
Isochaetides (Peloscolex), 5,45
   curvisetosus, 5,32,45
   freyi. 5,32,46
kessleri americanus, 7,28,51
   TTubTfexTTT
lacteus (R"hizpdri1us), 6,33,50
limnobius (Aulodrilus), 5,30,44
LimnodriTus, 5
   angustipenis, 5,36,37,46
   ceryix, 57M, 39,46
      Tvariant form), 6,38,39,46
   claparedianus, 6,38,39,46
   hoffmeisteTTT 6,38,39,45,46
      (spirialis form), 6,36,37,47
      (variant form), 6,38,39,47
   maumeensis, 6,38,39,47
   profundicp'la. 6,36,37,47
   psammophilus, 6,36,37,48
   rubripenis, 6,36,37,48
   silvani, 6,36,39,48
   udekemianus, 6,32,36,37,48
                                    60

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longidentus, 49,50
   (Quistadrilus multisetosus), 6,13,

mastix (Ilypdrilus). 5,16,45
maumeensis (Limnodrilus). 6,38,39,47
mi nutus (Psammoryctides), 6,25,49
moldaviensis (Potamothrix), 6,34,49
Monopylephorus, 6,
   he!obi us. 6,30.48
montana (RFyacodrilus), 6,20,50
multisetosus (QuistadVilus), 6,13,14,
   49
   longidentus, 49,50
   multisetosus, 49,50
nerthus (TubTFex), 7,22,52
nevadana (Varichaeta), 7,28,52
   (Isochaeta), 52
newfei (TuSFex), 52
nikolskyi (Spirosperma), 7,13,16,51
oregonensis (Peloscolex), 51
pacifica fVarichaeta), 7.27.52
   (Isochaeta), 52
Peloscolex, 45,46,52
   curvisetosus. 45
   freyi, 46
   oregonensis, 51
   superiorensis, 52
   yariegatus, 51
Phallodmus. 6
   hallae, 6,35,48
pigueti (Aulodrilus), 5,17,44
pluriseta (Aulodrilus). 5,19,44
PotamothfixTl>
   bavaricus, 6,25,48
   bedoti 7^.24,48
   hammoniensis, 6,25,49
   moldaviensis, 6,34,49
   vejcfovskyi, 6,18.49
profundicpla (Limnodrilus), 6,36,37,47
psammophilus (Limnodrilus). 6,36,37,48
Psammprycti des, 6
   barbatus, "g, 20,49
   caliform anus, 6,25,49
   convolutus, 6,28,49
   minutus,T, 25,49
 unctatus (Rhyacodrilus), 6,21,50
 uistadrilus, 6
   multisetosus 6,13,14.49
      longidentus, 49,50
      multi setgsus,  49,50
Rhizodrilus, 6
   lacteus. 6,33,50
    Rhyacodrilus. 6,
       brevidentatus, 6,18,50
       coccineus, 6,19,25,50
       falciformls, 6,35,50
       montana, "6720,50
       punctatus, 6,21,50
       sodalisT'6,25.50
    rubripenis (Limnodrilus), 6,36,37,48
    silvani (Limnodrilus). 6.36.39,48
    soda!is (RhyacodrilTTs). 6,25,50
    sowerbyi TSranchiura)'. 5,12,17,42,45
    speciosus cf. (Haber), 5,23,24,45
    (spiralis form), 6,36,37,47
       (Limnodrilus hoffmeister), 6,46
       47
    spiral is (Camptodrilus). 47
    Spirospenria, /
       beetpnTT 7,15,51
       carolinensis. 7,16,51
       ferox, 7,15,51
       nTkoTskyi, 7,13,16,51
       (Limnodrilus), 6
    superiorensis (Tubifex), 7,27,47
       (Peloscolx), 52
    Telematodrilus, 7
       vejdovskyiT 7,29,51
    tempietoni (Ilyodrilus). 5,28,45,52
    Tubifex, 7.5T^
       liamiani, 7,21,51
       ignotus. 7,22,51
       kessleri.7.28
         americanus, 7,28,51
       nerthus, 7,22,52
       newfei, 52
       superiorensis, 7,27,52
       tubifex, 7,23,45,52
    tubifex (Tubifex). 7,23,45,52
    udekemianus (Limnodri1 us). 6,32,
       36,37,48
    (variant form), 6,38,39,47
       (Limnodrilus hoffmeister), 6,45,46
    (variant form), 6,38,46
       (Limnodri 11 us cervjx), 6,46
    Varichaeta (Isochaeta), 7,52
       nevadana. 7,28,52
       pacifica, 7,27,52
    van egatus (Pel oscol ex), 51
    vejdovskyanum (Bothrionerum), 5,31,44
       ?T"^
    vejdovskyi (Potamothrix), 6,18,49
    vejdovskyi (Telematodrilus), 7,29,
61
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