University of Illinois Library at Urbana-Champaign ACES ACES LIBRARY UNIVERSITY LIBRARY UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN The person charging this material is responsible for its renewal or return to the library on or before the due date. The minimum fee for a lost item is $1 25.00, $300.00 for bound journals. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. Please note: self-stick notes may result in torn pages and lift some inks. Renew via the Telephone Center at 217-333-8400, 866-262-1510 (toll-free) or circlib@illinois.edu. Renew online by choosing the My Library Account option at: http://www.library.illinois.edu/catalog/ APR 1 8 Field Guide to Freshwater Mussels of the Midwest Field Guide to Freshwater Mussels of the Midwest Kevin S. Cummings Christine A. Mayer Illinois Natural History Survey • Champaign December 1992 Manual 5 Illinois Natural History Survey, Lorin I. Nevling, Chief A Division of the Illinois Department of Energy and Natural Resources Illinois Natural History Survey Natural Resources Building 607 East Peabody Drive Champaign, Illinois 61820 Printed by authority of the state of Illinois 81981— 3M— 12-92 second printing 556807 — 3M — 7-94 Editors: John Ballenot, Alison Fong Weingartner About the authors: Kevin S. Cummings is an Associate Research Biologist, and Christine A. Mayer is an Assistant Research Biologist with the Illinois Natural History Survey, Center for Biodiversity, in Champaign. Partial funding for the preparation of this field guide was provided by the U.S. Fish & Wildlife Service, Region 3 Office, Twin Cities, Minnesota; the Illinois Department of Conservation, Division of Natural Heritage, Springfield, Illinois; and the Mussel Mitigation Trust, Cincinnati, Ohio. The Indiana Academy of Science provided partial funding for the second printing of this manual. Library of Congress Catalog Card Number: 92-83870 ISBN: 1-882932-00-5 Printed in the United States of America Citation: Cummings, K.S., and C.A. Mayer. 1992. Field guide to freshwater mussels of the Midwest. Illinois Natural History Survey Manual 5. 194 pp. ACES LIBRARY r O § €^77 |j. 570 (; iL/s iyi i no. *3 I To the memory of Dr. Max R. Matteson ( 1909-1990 ) and field biologists everywhere Contents Foreword xi Acknowledgments xiii Introduction 1 Mussel Biology and Life History 1 Economic Importance 3 Conservation and Status 4 How to Collect Mussels 4 How to Use This Book 6 Explanation of Species Accounts 9 Text 9 Photographs 1 1 Maps 12 Glossary 1 6 Key to Freshwater Bivalves 18 Species Accounts 21 Subfamily Cumberlandinae Spectaclecase Cumberlandia monodonta 22 Subfamily Ambleminae Washboard Megalonaias nervosa 24 Pistolgrip Tritogonia verrucosa 26 Winged mapleleaf Quadrula fragosa 28 Mapleleaf Quadrula quadrula 30 Rabbitsfoot Quadrula cylindrica 32 Monkeyface Quadrula metanevra 34 Warty back Quadrula nodulata 36 Pimpleback Quadrula pustulosa 38 Threeridge Amblema plicata 40 Ebonyshell Fusconaia ebena 42 Long-solid Fusconaia subrotunda 44 Vlll Mussels of the Midwest Wabash pigtoe Fusconaia flava 46 Purple wartyback Cyclonaias tuherculata 48 Sheepnose Plethohasus cyphyus 50 White wartyback Plethohasus cicatricosus 52 Orange-foot pimpleback Plethohasus cooperianus 54 Clubshell Plewohema clava 56 Round pigtoe Pleurohema coccineum 58 Rough pigtoe Plewohema plenum 60 Ohio pigtoe Plewohema cordatum 62 Pyramid pigtoe Plewohema ruhrum 64 Elephant-ear Elliptio crassidens 66 Spike Elliptio dilatata 68 Cracking pearlymussel Hemistena lata 70 Pondhorn Uniomerus tetralasmus 72 Subfamily Anodontinae Paper pondshell Utterhackia (-Anodonta) imhecillis 74 Flat floater Anodonta suhorhiculata 76 Giant floater Pyganodon (-Anodonta) grandis 78 Cylindrical papershell Anodontoides ferussacianus 80 Squawfoot Strophitus undulatus 82 Elktoe Alasmidonta marginata 84 Slippershell mussel Alasmidonta viridis 86 Rock-pocketbook Arcidens confragosus 88 Salamander mussel Simpsonaias amhigua 90 White heelsplitter Lasmigona complanata 92 Fluted-shell Lasmigona costata 94 Creek heelsplitter Lasmigona compressa 96 Subfamily Lampsilinae Kidney shell Ptychohranchus fasciolaris 98 Threehom wartyback Ohliquaria reflexa 100 Fanshell Cyprogenia stegaria 102 Mucket Actinonaias ligamentina 104 Butterfly Ellipsaria lineolata 106 Hickorynut Ohovaria olivaria 108 Round hickorynut Ohovaria subrotunda 110 Ring pink Ohovaria retusa 112 Deertoe Truncilla truncata 1 14 Fawnsfoot Truncilla donaciformis 116 Contents * Scaleshell Leptodea leptodon 1 1 8 Fragile papershell Leptodea fragilis 120 Pink papershell Potamilus ohiensis 122 Pink heelsplitter Potamilus alatus 124 Bleufer Potamilus purpuratus 126 Fat pocketbook Potamilus capax 128 Lilliput Toxolasma parvus 130 Purple lilliput Toxolasma lividus 132 Texas lilliput Toxolasma texasensis 134 Black sandshell Li gumia recta 136 Pondmussel Li gumia subro strata 138 Ellipse V enustaconcha ellipsiformis 140 Rayed bean Villosa fabalis 142 Rainbow Villosa iris 144 t Little spectaclecase Villosa lienosa 146 Yellow sandshell Lamp silis teres 148 Fatmucket Lampsilis siliquoidea 150 Higgins eye Lampsilis higginsi 152 Pink mucket Lampsilis abrupta 154 Plain pocketbook Lampsilis cardium 156 Pocketbook Lampsilis ovata 158 Wavy-rayed lampmussel Lampsilis fasciola 160 Snuffbox Epioblasma triquetra 162 Catspaw Epioblasma obliquata 1 64 Tubercled blossom Epioblasma torulosa 166 Northern riffleshell Epioblasma rangiana 168 Leafshell Epioblasma flexuosa 170 Round combshell Epioblasma personata 170 Tennessee riffleshell Epioblasma propinqua 170 Wabash riffleshell Epioblasma sampsonii 170 Fingernailclams and Peaclams (Family Sphaeriidae) Asian Clam Corbicula fluminea 174 Zebra Mussel Dreissena polymorpha 176 Literature Cited 179 L Additional Reading 181 Index 191 172 Foreword This field guide to freshwater mussels is the fifth contribution to a series that has been published at very irregular intervals. The first in the series of Illinois Natural History Survey manuals was published in 1936, and the fourth was issued nearly three and a half decades ago. Previous volumes covered wildflowers, snails, shrubs, and mammals. Freshwater mussels are an interesting group of animals that are not particularly well known by the public even though most people exhibit an innate curiosity about them. Interest seems to have waxed and waned in concert with the worth of their shells in the commercial marketplace. Today the commercial exploitation of mussels, particularly in the Mississippi and Ohio river drain¬ ages, is focused on shells to be used in the Japanese cultured pearl industry. A nascent cultured pearl industry is only begin¬ ning in this country. Much of the current public interest in mussels has been stimulated by the recently introduced zebra mussel and the economic havoc it has created in some parts of its new and rapidly expanding range in North America. Professional biologists and informed amateurs alike have recognized that freshwater mussels are particularly sensitive to anthropogenic changes in our waterways. Thus, these mussels can be used to judge stream quality or the degree of degradation. It is especially meaningful to follow changes in mussel popula¬ tions over time. Because our predecessors assembled systematic collections that have been carefully maintained and because of the extensive efforts of the authors and others to reexamine watersheds and relocate previously known localities for some species, we have a better understanding of trends regarding species distribution and populations. This knowledge offers little encouragement or cause for contentment, however, because more than half of the mussel species of the Midwest are threatened or Xll Mussels of the Midwest endangered. No other major group of midwestem animals is so imperiled. Identification is usually the essential first step to unlocking information about a species. For this reason, this field guide includes color photographs and maps to assist the user in identi¬ fying mussels with a minimum of effort and specialized knowl¬ edge. I believe the user will find this approach a utilitarian one that will lead to new knowledge of, and appreciation for, this important group of organisms. Champaign, Illinois December 7, 1992 Lorin I. Nevling Chief Acknowledgments This field guide was conceived in discussions with Chris Iverson (formerly with the Indiana Department of Natural Resources), and his help in getting the ball rolling is much appreciated. Funding for the compilation of this book was provided by the U.S. Fish and Wildlife Service (Region 3 Office), the Illinois Department of Conservation-Division of Natural Heritage, and the Mussel Mitigation Trust. The help and patience of Ron Refsnider and Craig Johnson (USFWS), Glen Kruse and Mike Sweet (IDOC), and Wayne Davis, John Marshall, and Bernard Huff (MMT) is gratefully acknowledged. We would like to thank Jeanine Berlocher, Art Bogan, Ron Cicerello, and Larry Page for providing insightful comments, reviews, and helpful discussion on various drafts of this field guide. We are especially grateful to the curators and collection managers of the museums visited for allowing us access to collections under their care. We thank our family and friends for continued support and encouragement. Finally, we extend special thanks to John Ballenot, Alison Fong Weingartner, Bill Mayer, John Parker Sherrod, and Mike Jeffords for assistance with editing, illustrations, and printing of the final draft. Introduction Found on every continent except Antarctica, freshwater mussels are most diverse in eastern North America, where they number nearly 300 species. Their large shells make mussels the most conspicuous mollusks in the waters of the Midwest. Freshwater mussels (also referred to as clams, naiades, or unionids) spend their entire life partially or wholly buried in mud, sand, or gravel in permanent bodies of water. The vast majority of species are found in streams, but a few are present in ponds or lakes. Although they can be found in almost any type of stream bottom, mussels are usually absent from, or rare in, areas of shifting sand or deep silt. Mussel Biology and Life History In most species of freshwater mussels the sexes are separate. Males release sperm into the water, the sperm enters the female via the incurrent siphon, and the eggs are fertilized internally. The fertilized eggs develop into an intermediate larval stage, termed glochidia (singular, glochidium). The glochidia are stored in the female’s gills, which function as a brood chamber as well as a means for obtaining oxygen. In the spring or summer, the glochidia are expelled into the water to begin the parasitic phase of their life cycle (Figure 1). The glochidia attach to an appropriate host, usually a fish, and form numerous cysts. Some species, in fact, possess a “lure” for attracting potential host fishes. Depending on the species of mussel, the glochidia are either internal parasites, on the gills, or external parasites, on the fins. Although some species are host- specific, others can use a wide variety of fishes as hosts. While encysted, the larvae change form and begin to resemble adults. After metamorphosis, the small, young mussels break free from the cysts and drop to the stream or lake bottom to begin an independent life. The period of attachment varies from 2 Mussels of the Midwest Figure 1. Generalized life cycle of freshwater mussels. Parasitic larval mussels (glochidia) attach to a host and encyst; the host is usually a fish (shown here: white crappie, Pomoxis annularis). After a few weeks the glochidia transform into juveniles and drop from the host. Two different strategies are employed: (1) internal hookless glochidia on the gills (plain pocketbook, Lampsilis cardium , on the left) or (2) external hooked glochidia on the fins (giant floater, Pyganodon [= Anodonta ] grandis, on the right). (After U.S. Fish & Wildlife Service 1990). about 1 to 25 weeks depending on the host, location of attach¬ ment, and water temperature. Freshwater mussels continuously pump water through their bodies. Water enters via the incurrent or branchial siphon and exits via the excurrent or anal siphon. During this pumping process, the mussel filters food from the water. The food consists of detritus, which is organic matter found on the stream or lake bottom, and plankton, composed of microscopic plants and animals suspended in the water. Introduction 3 Mussels are long-lived, with many species living more than 10 years and some reported to live more than 100 years. Thin- shelled species (floaters and papershells, for example) grow much faster than thicker-shelled species (threeridges and mapleleafs, for example). In many species, the surface of the shell has distinct black lines or ridges, which are believed to represent winter rest periods. The rest periods, or growth rings, are often used to estimate the age of a mussel. Mussels are an important food source for many animals, including muskrats, minks, otters, fishes, and some birds. Large piles of freshly cleaned mussels, called middens, can be found along the banks of a river or lake where muskrats are actively foraging. These middens often contain many species and can be one of the best places to find shells. Economic Importance Freshwater mussels were collected and used in various ways by Native Americans, particularly the mound-building tribes of the Midwest, long before Europeans set foot in North America. Mussels were not only eaten but also used for tempering pottery and for making utensils, tools, and jewelry (Baker 1930, Matteson 1953). In the late 1800s and early 1900s, enormous numbers of freshwater mussels were harvested to make pearl buttons for clothing, and button-making was a multimillion-dollar industry. By 1912, nearly 200 factories were operating in towns such as Muscatine, Keokuk, Peoria, and Beardstown (Coker 1919). The pearl-button industry collapsed, however, with the invention and widespread use of plastics in the 1940s and 1950s, and some freshwater mussel populations subsequently recovered. By the 1950s, the Japanese had found a new use and market for freshwater mussels: cultured pearls for jewelry. Once har¬ vested, mussels are sorted and steamed or cooked out to remove the soft parts. The shells are then cut and finished into beads for insertion into an oyster to serve as nuclei for cultured pearls. Today thousands of tons of mussel shells (particularly those of 4 Mussels of the Midwest washboard and threeridge mussels) are harvested each year and exported to Japan to supply the cultured pearl industry. Conservation and Status Freshwater mussels are one of the most endangered groups of animals in North America. Surveys conducted over the past few decades have documented significant declines in mussel popula¬ tions across the continent. Among the factors thought to be responsible for the decline are overharvest; siltation of their habitat from agriculture, poor land management, channelization, and impoundments; competition from exotic species such as the zebra mussel; and pollution by herbicides, pesticides, and other chemicals. One result of the status surveys has been the designa¬ tion of many mussels as state-endangered or federally endangered species. In the United States, 42 mussels are listed as federally endangered or threatened, and another 70 have been proposed or are candidates for listing (USFWS 1991a, 1991c). How to Collect Mussels Before collecting mussels it is advisable to contact the Depart¬ ment of Conservation or the Department of Natural Resources to find out whether there are any restrictions and to obtain any permits that may be required. Because of the rarity of many of the native species, live mussels should never be collected without prior permission. One can still build a nice collection by taking only shells and returning all live mussels to the stream or lake. Perhaps the best place to begin looking for shells is along the bank of a medium-sized or large river when the water is at its lowest level (usually July to September). Although a few species can withstand some dessication, most are found in permanently flowing streams or lakes that contain water year-round. Mussels can be found in a variety of habitats but are most abundant on shoals, where they live in gravel or a mixture of sand, mud, and gravel. A wide variety of shells can often be found along the shore in piles or “middens” left by muskrats or raccoons. The simplest and possibly the most effective method of collecting mussels is by hand-picking along the shore or in the Introduction 5 stream. A small net bag or old potato sack makes a good con¬ tainer for holding shells in the field. With a little practice, you can learn to see mussels in the shallows of clear streams. Usually the only part visible is the posterior end, with the incurrent and excurrent siphons protruding from the stream bottom. A mussel can often be spotted at one end of the meandering trail it leaves in the sand as it moves from place to place. For your specimens to have scientific as well as aesthetic value, you need to keep accurate labels and records of field observations. After specimens are collected, a label should be made immediately and placed in the bag with the specimens; it should include the following information: the name of the body of water, road or bridge crossing, distance and direction from the nearest town, the county and state, the date, and the name of the collectors. Other information, such as water temperature, depth, current velocity, bottom type, and time spent collecting, can be recorded in a field notebook. Locality data should be written in pencil or india ink on a good grade of label paper so the label will not mold or disintegrate in the bag. Specimens without sufficient locality data are essentially worthless, so it is extremely impor¬ tant to accurately label specimens. Once collected, the shells should be cleaned with warm water and a brush or teflon scrub pad to bring out the true colors and other markings needed for identification. After cleaning, locality data or a numbering system used to tie that specimen to a particular locality should be written directly in the shell with a pencil or india ink. If, after cleaning, you still have trouble identifying your specimen, you can often send it to a specialist for verification. Prior arrangements should be made with the curator of a museum before sending specimens for identification. By keeping well-organized and curated collections, many amateurs have made significant contributions to malacology (the study of mollusks) over the years. Most of the major museums of the world contain donated private collections that are available for study by specialists for years to come. See van der Schalie (1941) for additional information about collecting shells. How to Use This Book This field guide is intended to help biologists, commercial shelters, amateur naturalists, teachers, and students identify freshwater mussels found in the streams and lakes of the Mid¬ west. It includes 78 species, over half of which are either rare, threatened, endangered, or extinct. The species are arranged in groups that approximate their systematic relationships; therefore, similar-looking species will often, but not always, be grouped together. An index to both the scientific and common names is given in the back of the book. To get you started looking in the right direction, a rough “key” to the major groups of freshwater bivalves is given on pages 18 and 19. The first thing to keep in mind when trying to identify a shell is that freshwater mussels are extremely variable with respect to coloration, shape, and size, both within and between species. Although some species (especially the pigtoes) can be difficult to tell apart without the aid of a specialist, nearly all of the mussels in the Midwest can be identified using a combination of written descriptions, photographs, and range maps. Perhaps the easiest way to identify a mussel shell is to match your specimen to one of the photographs. If you can’t find an exact match, pick the one that looks the closest and refer to the text for the key characters and similar species to eliminate those that look similar. Once a tentative identification has been made, check the range map to see if the species you have chosen is found in your area. When the range map and photograph have been checked, read the full species description to confirm your identification. To identify specimens, you first need to know a little about the basic anatomy of a mussel shell (Figure 2). Although this field guide keeps jargon to a minimum, the descriptions include technical terms used to describe anatomical features. A glossary of terms commonly used in the text is given on pages 16 and 17. Definitions are those used by Parmalee (1967) or Burch (1975). How to Use This Book 7 DORSAL Hinge Posterior ridge Sulcus Beak (umbo) Pustules POSTERIOR ANTERIOR Lateral teeth Interdentum Pseudocardinal teeth Muscle scars DM Pallial line VENTRAL Figure 2. The major features of a freshwater mussel shell, as exemplified by the mapleleaf ( Quadrula quadnda). The drawing shows the exterior of the right valve (top) and the interior of the left valve (bottom). Figure 2 is a drawing of a typical mussel shell and its salient features. The anterior or front end of a mussel can be determined by the position of the umbo and pseudocardinal teeth, both of which are always located anteriorly. Among the features most 8 Mussels of the Midwest often cited in the description of a mussel is the beak sculpture, which consists of the ridges or raised lines found on the umbo. Beak sculpture can vary from simple V-shaped lines to a series of wavy, double-looped ridges. The teeth are also important for identifying a shell. The lateral teeth can be absent, straight, or curved; single or double; smooth or serrated. The pseudocardinal teeth can be absent, small and peglike, or prominent. The depth of the beak cavity is often used to distinguish between species. The beak cavity can be absent, shallow, moderately deep, or deep. External characters used to identify species include the shape, number, and arrangement of pustules on the surface; the presence or absence of a sulcus or shallow depression running from the beaks to the ventral margin of the shell; and the promi¬ nence of the posterior ridge. In addition, the color of the perio- stracum (outside) and nacre (inside) and the external texture of the shell are often used to differentiate between species. Although many species are highly variable with respect to color (both outside and inside), others are relatively consistent in this regard. Some mussels lacking obvious bumps, ridges, or pustules have a characteristic rough or satinlike finish on the external surface. The characters mentioned above are those most often used to discern between species on the basis of the shell. Most other anatomical features used in identification are associated with the animal itself, often called the “soft parts.” Some of the most often used features include the size and shape of the marsupium, glochidia, labial palps, and siphons. References to these features can be found in more comprehensive books on mussels (e.g., Baker 1928, Parmalee 1967, Oesch 1984). Explanation of Species Accounts Each species account has three components: text, photograph, and range map. A brief explanation of these components follows. Text Each account begins by listing a common name as well as the scientific name of the mussel. The names in this book are largely those used in American Fisheries Society Special Publication 16, Common and Scientific Mantes of Aquatic Invertebrates from the United States and Canada: Mollusks (Turgeon et al. 1988). Exceptions to this list are that subspecies are not recognized and a few modifications have been made to reflect changes since the publication of the 1988 list (Hoeh 1990, Cummings and Berlocher 1990, Bogan personal communication). The text in each species account is divided into the following sections: other common names, key characters, similar species, description, habitat, and status. Other common name(s). Common names given to mussels are regional and can vary considerably from place to place. Some of the common names frequently encountered in the literature or in the field are included in this section. Differences in common names can create problems for the governmental resource agencies responsible for managing mussels. The proper identifi¬ cation and recording of species is essential for accurate data gathering and analysis of commercial harvest statistics or sightings of endangered species. Key characters. This section summarizes a few of the more prominent features used to identify each species. The key characters may be enough to identify a particular specimen, but in most instances you should read over the entire description to confirm your identification. Similar species. A list of those species similar in color, shape, and size is included for comparison, when some doubt as 10 Mussels of the Midwest to the identity remains. The species listed may or may not be closely related. Description. The descriptions are for shells only and do not include any of the characteristic features of the animal itself. The first paragraph describes the external parts of the shell, including coloration, shape, size, surface features, and thickness. A near¬ maximum adult size is also given in inches and its centimeter equivalent; most specimens will be somewhat smaller. The second paragraph covers internal features, including the pseudocardinal teeth, lateral teeth, depth of the beak cavity, and nacre color. Habitat. Mussels vary considerably with respect to their habitat preferences. Some are restricted to a specific habitat type (for example, small creeks), whereas others can be found in almost any permanent body of water. Each account lists the size of the stream (headwater, creek, small, medium, or large river) in which the species is typically found. The habitat descriptions also include statements on the composition of the bottom (for ex¬ ample, silt, mud, sand, or gravel) and, occasionally, water flow. Status. Over half of the species in this field guide are considered rare, threatened, or endangered by at least one of the states in the Midwest. Each account gives a general statement regarding the species distribution and abundance, often followed by information on its status in individual states. Not all states use the same criteria in determining or labeling special-status species. For example, Missouri uses “rare” as opposed to “threatened” for those species that are likely to become endangered if conditions worsen. This field guide also employs several categories used by the U.S. Department of the Interior. An “endangered” species as defined by the federal government is any species that is in danger of becoming extinct throughout all or a major portion of its range. A “threatened” species is one that is likely to become an endan¬ gered species within the foreseeable future throughout all or a major portion of its range (USFWS 1991b). Federal candidate species are divided into several categories (USFWS 1990b). A “Category 1” classification is used for species for which the U.S. Explanation of Species Accounts 1 1 Fish and Wildlife Service has “enough substantial information on biological vulnerability and threat(s) to support proposals to list them as endangered or threatened species/' Species for “Category 2” status are those for which there is some evidence for vulner¬ ability but not enough data for them to be listed as endangered or threatened. “Category 3A” species are those that the Fish and Wildlife Service considers extinct. Photographs The photographs in this field guide are of specimens in the mollusk collections of the Illinois Natural History Survey, Champaign (INHS), and the University of Illinois Museum of Natural History, Urbana (UIMNH). The shells were selected because they were considered representative of their species. In cases in which males and females are noticeably different, both are shown. Each plate shows the right valve, so that the front or anterior end is always to the right. The photos are not to scale, but much larger species are usually shown somewhat larger on the page. The length of each specimen shown is given in the photo caption. Although this field guide is intended for use in identifying freshwater mussels, we have included photographs of representa¬ tives of some of the other bivalves found in the Midwest: a representative of the native fingernailclam or peaclam family (Sphaeriidae), the introduced Asian clam ( Corbicula ), and the recently introduced zebra mussel ( Dreissena ). Both the Asian clam and zebra mussel are prolific breeders and have caused severe problems for industries and municipalities that utilize lake or river water by clogging intake lines and blocking the flow of water. The zebra mussel in particular is having a major impact on our native mussel species. Zebra mussels will attach themselves to any firm object, including freshwater mussels. A colony of zebra mussels attached to a freshwater mussel will impede the flow of water, food, and oxygen and will eventually kill it. Researchers are investigating ways to control these unwanted pests without further endangering other species found in our rivers and lakes. 12 Mussels of the Midwest Maps Knowing where a specimen was collected can be very helpful when trying to identify it. The range maps in this field guide cover the Ohio, Mississippi, and Red river drainages in Minne¬ sota, Wisconsin, Iowa, Missouri, Illinois, Indiana, and Ohio and part of the upper Great Lakes drainage (Figure 3). Mussels endemic to the Ozarks or those that reach the northern limit of their range in southern Missouri are not included but can be found in Missouri Naiades. A Guide to the Mussels of Missouri (Oesch 1984). Many of the species found in the Midwest are also present in the Great Lakes and their tributaries. Unfortunately, specific distributional information is unavailable, and maps depicting the range of species found in the Great Lakes drainage in Indiana, Michigan, Minnesota, and Ohio are not included. However, nearly all of the mussels found in the Great Lakes drainage are described and illustrated in this book. The maps on the following pages show the approximate historic ranges of mussels in the Midwest. The maps are not meant to be comprehensive and will undoubtedly change as Figure 3. The area covered by this field guide. Explanation of Species Accounts 13 additional data are collected. Within these ranges, gaps in distribution may occur in areas not suitable for mussels. For example, the cylindrical papershell occurs throughout much of the Midwest but is found only in small creeks and the headwaters of large rivers; it is therefore absent from many of the streams within its range. The information used to prepare the maps was taken from various sources. The Illinois and Indiana portions of the maps were compiled from examination of more than 85,000 specimens in the following collections: Academy of Natural Sciences, Philadelphia; Chicago Academy of Sciences; Field Museum of Natural History; Illinois Natural History Survey; Museum of Comparative Zoology, Harvard; Ohio State University Museum of Zoology; University of Illinois Museum of Natural History; University of Michigan Museum of Zoology; and the National Museum of Natural History of the Smithsonian Institution. Range maps for the other states were compiled from the following publications or technical reports: Bright, R.C., E. Plummer, and D. Olsen. 1989. A survey of the mussels of the Zumbro River drainage, southeastern Minnesota. Bell Museum of Natural History, University of Minnesota. 27 pp. + illustrations and appendices. Bright, R.C., C. Gatenby, D. Olsen, and E. Plummer. 1990. A survey of the mussels of the Minnesota River, 1989. Bell Museum of Natural History, University of Minnesota. 36 pp. + illustrations and appendices. Clarke, A.H. 1981. The Tribe Alasmidontini (Unionidae: Anodontinae), Part I: Pegias , Alasmidonta , and Arcidens. Smithsonian Contributions to Zoology No. 326. 101 pp. - 1985. The Tribe Alasmidontini (Unionidae: Anodontinae), Part II: Lasmigona and Simpsonaias. Smithsonian Contributions to Zoology No. 399. 75 pp. 14 Mussels of the Midwest Cvancara, A.M. 1970. Mussels (Unionidae) of the Red River Valley in North Dakota and Minnesota, U.S.A. Malacologia 10(l):57-92. Davis, M. 1987. Freshwater mussels (Mollusca: Bivalvia: Unionidae) of the Cannon River drainage in southeastern Minnesota. Minnesota Department of Natural Resources. 23 pp. + appendices. Dawley, C. 1947. Distribution of aquatic mollusks in Minnesota. American Midland Naturalist 38(3):67 1-697. Frest, T.J. 1987. Mussel survey of selected interior Iowa streams. University of Northern Iowa. Final Report to Iowa Department of Natural Resources and U.S. Fish & Wildlife Service. 354 pp. Johnson, R.I. 1980. Zoogeography of North American Unionacea (Mollusca: Bivalvia) north of the maximum Pleistocene glacia¬ tion. Bulletin of the Museum of Comparative Zoology, Harvard University 1 49(2):77— 1 89. Mathiak, H.A. 1979. A river survey of the unionid mussels of Wisconsin 1973—1977. Sand Shell Press, Horicon, Wisconsin. 75 pp. Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of Missouri. Missouri Department of Conservation, Jefferson City, Missouri. 270 pp. Stansbery, D.H., K.E. Newman, K.G. Borror, and C.B. Stein. 1985. Literature records of bivalve mollusks of the Muskingum River system, Ohio. Ohio State University Museum of Zoology Reports 1985(1): 1-472. Watters, G.T. 1988. The naiad fauna of selected streams in Ohio. Ohio State University. Final Report to Ohio Department of Natural Resources. 440 pp. Explanation of Species Accounts 15 - 1992. Distribution of the Unionidae in South Central Ohio. Malacology Data Net 3( l^l):56-90. Williams, J.C., and G.A. Schuster. 1989. Freshwater mussel investigations of the Ohio River. Mile 317.0 to mile 981.0. Kentucky Department of Fish and Wildlife Resources, Division of Fisheries. 57 pp. Wilson, C.B., and E. Danglade. 1914. The mussel fauna of central and northern Minnesota. U.S. Bureau of Fisheries Document No. 803. 26 pp. + 1 map. Glossary Knowledge of the following terms is important for understanding the species accounts. Anterior end — the shorter end of the shell as measured from the umbo; also considered the front end Beak — the raised part of the dorsal margin of the shell; also called the umbo Beak cavity — the depression or pocket on the inside of each valve leading into the beak Beak sculpture — the raised loops, ridges, or bumps on the umbo Chevron — a V-shaped marking Compressed — flattened or pressed together laterally Concentric — having a common center Distal — away from the center or origin Dorsal — referring to the top part of the shell where the hinge is located Elliptical — having the form of an ellipse, or oval Elongate — long or extended Extirpated — locally extinct Growth lines — darkened lines on the surface of the shell indicating periods of rest during growth Hinge — the elastic part of the shell that unites the valves along the top of the shell Inflated — swollen or expanded Interdentum — a flattened area between the pseudocardinal and lateral teeth Iridescent — exhibiting rainbow colors Lateral teeth — the elongated teeth along the hinge line of the shell Left valve — the left half of the shell when the dorsal edge or hinge is facing up and the anterior end is directed forward (away from the collector) Glossary 17 Nacre — the interior layer of the shell, usually white, pink, salmon, or purple and iridescent Oblong — having the shape of or resembling a rectangle or ellipse Ovate — egg-shaped Pallial line — a linear depression on the inside of the shell Periostracum — the outside layer or covering of the shell Plications — folds Posterior end — the longer end of the shell as measured from the umbo; also considered the back end; also the end with the siphons, usually sticking above the stream bottom Posterior ridge — the ridge on the back half of the valve running from the umbo to the posterior ventral edge Posterior slope — the area along the dorsal part of the shell between the posterior ridges of the valves Pseudocardinal teeth — the triangular, often serrated, teeth located on the anterior-dorsal part of the shell Pustule — a bump or raised knob on the outside surface of the shell Quadrate — square Right valve — the right half of the shell when the dorsal edge or hinge is facing up and the anterior end is directed forward (away from the collector) Serrated — notched or grooved Shell margin — the circumference of a valve outline when laid flat; also known as the edge Solid — thick or heavy Striated — marked with lines or grooves Sulcus — a shallow depression or furrow on the outside surface of the shell Truncate — having the end shortened or squared off Tubercle — a pointed, rounded, or knoblike projection on the shell Umbo — the inflated dorsal part of the shell; also called the beak Valve — one of the two halves of the shell Ventral — referring to the bottom edge of the shell J Key to Freshwater Bivalves Freshwater Mussels Shell elongated, thin to moderately thick. Beak sculpture concen¬ tric. Surface of the shell dark brown to black. Pseudocardinal and lateral teeth poorly developed; present only as a thickened ridge. Sexual differences in the shell indistinct. Found in areas of reduced flow (around large boulders) in large rivers with swift currents . Cumberlandinae pp. 22-23 Shell usually thick and solid. Beak sculpture generally indistinct. Surface of the shell brown, chestnut, or tan, rays or bands greatly reduced or absent. Pseudocardinal and lateral teeth usually well developed. Sexual differences in the shell indistinct. Most often found in streams, but occasionally present in lakes or large impoundments . Ambleminae pp. 24-73 Shell thin, more or less elongated. Beak sculpture usually double- looped, occasionally concentric. Surface of the shell green, greenish brown, or black with or without fine green rays. Pseudo¬ cardinal and lateral teeth absent, reduced, or poorly developed. Sexual differences in the shell indistinct. Found in ponds, lakes, or the quiet-water areas of streams . Anodontinae pp. 74-97 Shell relatively thin to moderately thick, rounded or oval to elongate. Beak sculpture generally double-looped but often indistinct. Surface of the shell mostly light yellow or tan with brightly colored rays or bands. Pseudoeardinal and lateral teeth usually well-developed. Sexual differences in the shell appar¬ ent — squared or truncated posteriorly in females, bluntly pointed posteriorly in males. Found in streams, occasionally in lakes or other impoundments . Lampsilinae pp. 98-171 Key to Freshw ater Bivalves 19 Fingernailclams and Peaclams Shell relatively small, whitish or cream-colored. Surface of the shell covered by numerous, very fine concentric rows of elevated lines (striae). Right valve has one cardinal tooth and two pairs of lateral teeth. Left valve has two cardinal teeth and two lateral teeth . Sphaeriidae pp. 172-173 Asian Clam Shell small (most under 2 inches), moderately thick, rounded. Surface of the shell yellowish brown to black, with numerous, evenly spaced, concentric, elevated ridges. Three cardinal teeth in each valve located below the umbo; two sets of serrated lateral teeth in each valve, paired on each side of the umbo in the right valve, single on each side in the left. Introduced into western North America in the 1920s and 1930s and spreading throughout the United States . Corbiculidae pp. 174-175 Zebra Mussel Shell small (most under 1 inch), moderately thick, triangular, and more or less elongated. Surface variably banded with black or brown and cream stripes. Introduced into the Great Lakes in the 1980s and spreading to large rivers and lakes throughout the United States . Dreissenidae pp. 176-177 22 Mussels of the Midwest Spectaclecase Cumberlandia monodonta (Say, 1829) Other common names None. Key characters Elongate shell, usually pinched in the middle, dark brown to black, with poorly developed teeth. Similar species Spike, black sandshell, salamander mussel. Description Shell oblong, elongate, and compressed. Anterior and posterior ends rounded. Ventral margin usually arched or pinched, occasionally straight. Shell thin in young, becoming thicker in older individuals. Umbos only slightly elevated above the hinge line. Beak sculpture, when visible, of three or four heavy ridges. Surface of shell smooth to somewhat rough, brown in young shells, becoming dark brown to black and rayless with age. Length to 8 inches (20.3 cm). Pseudocardinal teeth small, tubercular; one in each valve in young individuals. Lateral teeth poorly developed or absent. Beak cavity moderately shallow. Nacre white, iridescent in young individuals and on the posterior fourth of shell in adults. Habitat Large rivers with swiftly flowing water, among boul¬ ders in patches of sand, cobble, or gravel in areas where current is reduced. Status Widely distributed but absent from many areas where it formerly occurred. Federal Candidate (Category 2). Extirpated from Ohio and possibly Indiana. Endangered in Illinois, Iowa, and Wisconsin. Watch List in Missouri. Subfamily Cumberlandinae 23 Cumberlandia monodonta, INHS 7445. Green River, Warren County, Kentucky. Length: 5.2 inches (13.2 cm). 24 Mussels of the Midwest Washboard Megalonaias nervosa (Rafinesque, 1820) Other common names Bald-pate, board. Key characters Large, black shell, heavily sculptured with V- shaped ridges in the front and large folds on the sides and back, particularly in smaller shells. Similar species Threeridge, rock-pocketbook. Description Shell large, thick, slightly elongate, rectangular, and compressed to moderately inflated. Anterior end rounded, posterior end truncated. Dorsal margin straight, ventral margin straight to slightly curved. A small wing with several ridges present behind the umbo (most evident in small shells, becoming indistinct in larger shells). Umbos not elevated above the hinge line. Beak sculpture of prominent double-looped ridges, enlarg¬ ing into bumps and folds on the posterior ridge. Upper shell with irregularly shaped tubercles or V-shaped ridges (covering the shell of juveniles). A series of large folds present on the posterior half of the shell. Periostracum rayless, light brown in juveniles, dark brown or black in adults. Length to 1 1 inches (27.9 cm). Pseudocardinal teeth well developed and serrated; two in the left valve, one in the right (occasionally with a small tooth on either side). Lateral teeth straight to slightly curved; two in the left, one in the right. Beak cavity fairly deep. Nacre white, often with purple or copper-colored blotches, iridescent posteriorly. Habitat Primarily large rivers with a good current; occasionally medium-sized streams in mud, sand, or gravel. Status Commercial species. May be common in its preferred habitat. Endangered in Ohio. Subfamily Ambleminae 25 Megalonaias nervosa , INHS 12568. East Fork White River, Lawrence County, Indiana. Length: 5.0 inches (12.7 cm). 26 Mussels of the Midwest Pistolgrip Tritogonia verrucosa (Rafinesque, 1820) Other common names Buckhorn, peanut, turkey wing. Key characters Elongate, posterior wing with folds, sides of the shell covered with pustules. Similar species Rabbitsfoot. Description Shell thick, elongate, and compressed. Anterior end rounded, posterior end squared or truncated in males, elongate and rounded in females. Dorsal margin straight to slightly curved, ventral margin usually arched. Umbos low, only slightly elevated above the hinge line. Beak sculpture of a series of pronounced ridges continuing down the sides. Entire shell (except the rounded posterior ridge of the female) covered with irregularly sized and arranged pustules. Periostracum green or light brown, becoming dark brown to black in older shells. Length to 8 inches (20.3 cm). Pseudocardinal teeth large, serrated, and well developed; two in the left valve, one in the right (occasionally with a small tooth on either side). Lateral teeth long, straight, and striated; two in the left valve, one in right. Beak cavity deep. Nacre white, iridescent posteriorly. Habitat Medium to large rivers in mud, sand, or gravel. Status Widespread but relatively uncommon. Endangered in Iowa. Threatened in Wisconsin. Subfamily Ambleminae 27 Tritogonia verrucosa , INHS 8935. Spoon River, Peoria County, Illinois. Length: 5.4 inches (13.7 cm). 28 Mussels of the Midwest Winged mapleleaf Quadrula fragosa (Conrad, 1835) Other common names False mapleleaf, hickory nut shell. Key characters Fairly thick shell with well-developed teeth. Squared in outline, an obvious wing behind the umbo with wide radiating ridges. Lateral surface of the shell with two rows of pustules separated by a sulcus or furrow. Similar species Mapleleaf, wartyback. Description Shell quadrate or square, thick, and moderately inflated. Anterior end rounded, posterior end squared or trun¬ cated. Dorsal margin straight, ventral margin curved in the anterior half, arched posteriorly. A pronounced wing present posterior to the umbo, with radiating rows of pustules or ridges. Umbos small and elevated above the hinge line. Beak sculpture of two rows of raised bumps or nodules that continue downward on the surface of the shell, separated by a furrow or sulcus. Periostracum variable, from yellowish green to light brown with faint rays in small shells, becoming greenish brown, chestnut, or dark brown in larger individuals. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed, serrated; two in the left valve, one in the right. Lateral teeth striated, fairly long, and straight; two in the left valve, one in the right. Beak cavity very deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers in mud, sand, or gravel. Status Federally Endangered. Only known extant population in the Midwest occurs in Wisconsin. 30 Mussels of the Midwest Mapleleaf Quadrula quadrula (Rafinesque, 1 820) Other common name Stranger. Key characters Fairly thick shell with well-developed teeth. Squared in outline, lateral surface with two rows of pustules separated by a sulcus. Similar species Winged mapleleaf, pimpleback, purple pimpleback, monkeyface, wartyback. Description Shell quadrate to rounded, thick, and somewhat inflated. Anterior end rounded, posterior end squared or trun¬ cated. Dorsal margin straight, ventral margin curved in the anterior half, straight or arched posteriorly. Umbos small and only slightly elevated above the hinge line. Beak sculpture of two rows of raised bumps or nodules that continue downward on the surface of the shell, separated by a furrow or sulcus. Rows of ridges or pustules on either side of sulcus and on posterior slope, rest of surface usually smooth. Periostracum variable, from yellowish green to light brown with faint rays in small shells, becoming greenish brown, chestnut, or dark brown in larger individuals. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed, serrated; two in the left valve (occasionally with a small tooth on either side), one in the right. Lateral teeth striated, fairly long, and straight; two in the left valve, one in the right. Beak cavity deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers and reservoirs with a mud, sand, or gravel bottom. Status Widespread and common. Commercial species. 32 Mussels of the Midwest Rabbitsfoot Quadrula cylindrica (Say, 1817) Other common names Smooth cob shell, spectaclecase mussel. Key characters Elongate, rectangular shell with pustules and V- shaped markings. Similar species Monkeyface, pistolgrip. Description Shell rectangular, elongate (about three times as long as high), thick, and compressed to moderately inflated. Anterior end rounded, posterior end squared or truncated. Dorsal and ventral margins parallel. Umbos low, only slightly elevated above the hinge line. Beak sculpture consists of two rows of knobs or ridges that continue down the lateral surface of the shell. Surface of the shell usually rough, with numerous tubercles on the anterior end and a series of large pustules or knobs along the posterior ridge. Periostracum green or light brown (darker in older shells) with yellow zigzag or chevron-shaped markings on the shell. Length to 5 inches (12.7 cm). Pseudocardinal teeth serrated and well developed; two in the left valve, one in the right. Lateral teeth very long and straight; two in the left valve, one in the right. Beak cavity deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers in mixed sand and gravel. Status Rare throughout its range. Endangered in Illinois, Indiana, Missouri, and Ohio. Subfamily Ambleminae 33 Quadrula cylindrical INHS 6974. North Fork Vermilion River, Vermil¬ ion County, Illinois. Length: 2.2 inches (5.6 cm). 34 Mussels of the Midwest Monkeyface Quadrula metanevra (Rafinesque, 1820) Other common name Knobbed rock shell. Key characters Rounded or squared shell with large knobs along the posterior ridge and a distinct indentation on the posterior margin that looks like a chimpanzee in profile. Distinc¬ tive zigzag markings on the shell (may be lacking in older individuals). Similar species Rabbitsfoot, mapleleaf, pimpleback, wartyback. Description Shell thick, rounded or rectangular, and moderately inflated. Anterior end rounded, posterior end squared or truncated and indented in the middle. Dorsal margin straight, area behind the umbos flattened into a wing, ventral margin curved. Umbos elevated above the hinge line. Beak sculpture of pronounced ridges or knobs that continue down the posterior ridge to the ventral margin of the shell. Shell rough, with numerous pustules on the anterior half and behind the umbos and a row of large knobs along the posterior ridge. Periostracum green or light brown (darker in older shells) with yellow zigzag or chevron¬ shaped markings on the shell. Length to 4 inches (10.2 cm). Pseudocardinal teeth serrated and well developed; two in the left valve, one in the right (occasionally with a small tooth on either side). Lateral teeth short, heavy, serrated and straight; two in the left valve, one in the right. Beak cavity deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers in gravel or mixed sand and gravel. Status Relatively uncommon but may be locally abundant. Endangered in Ohio. Threatened in Wisconsin. Subfamily Ambleminae 35 Quadrula metanevra, INHS 6221. Wabash River, Tippecanoe County, Indiana. Length: 2.4 inches (6.1 cm). 36 Mussels of the Midwest Wartyback Quadrula nodulata (Rafinesque, 1820) Other common names Two-horned pocketbook, winged pimpleback, pimpleback, nodule shell, winged orb shell. Key characters Rounded shell with two rows of paired knobs or pustules on the posterior half of the shell; no sulcus. Similar species Pimpleback, mapleleaf, monkeyface, threehorn wartyback. Description Shell relatively thick, rounded, and inflated. Anterior end rounded, posterior end squared or truncated. Dorsal margin straight, area behind the umbos flattened into a small wing, ventral margin broadly rounded. Umbos rounded and elevated above the hinge line. Beak sculpture, if visible, of small ridges. Shell smooth except for two rows of knobs, usually occurring in pairs, that extend from the umbos to the ventral margin of the shell. No sulcus. Periostracum rayless and uni¬ formly yellowish green or light brown, becoming darker with age. Length to 3 inches (7.6 cm). Pseudocardinal teeth serrated and well developed; two in the left valve, one in the right (occasionally with a small tooth on either side). Lateral teeth short, heavy, serrated and straight to somewhat curved; two in the left valve, one in the right. Beak cavity deep. Nacre pearly white, iridescent posteriorly. Habitat Large rivers or in the lower sections of medium-sized rivers in sand or fine gravel. Status Uncommon, but locally abundant. Endangered in Ohio. Threatened in Wisconsin. Rare in Missouri. Subfamily Ambleminae 37 Quadrula nodulata, INHS 10227. Mississippi River, Scott County, Iowa. Length: 1.9 inches (4.8 cm). 38 Mussels of the Midwest Pimpleback Quadrula pustulosa (Lea, 1831) Other common names Wartyback, warty pigtoe. Key characters Rounded shell, a green stripe on the umbo, usually densely covered with pustules. Beak cavity deep and open, not compressed as in the purple wartyback. Similar species Orange-foot pimpleback, purple wartyback, wartyback, mapleleaf. Description Shell thick, rounded, and compressed to moderately inflated. Anterior end rounded, posterior end rounded to some¬ what truncated. Dorsal margin straight, ventral margin curved. Umbos elevated above the hinge line. Beak sculpture, when present, of two or three very small ridges. Shell normally smooth on the anterior half; posterior half or two-thirds covered with pustules or bumps (rarely absent). Periostracum yellowish-green to light brown in small shells, becoming chestnut to dark brown in older shells. A broad, broken green ray present on the umbo extending toward the ventral margin, may be indistinct on older shells. Length to 4 inches (10.2 cm). Pseudocardinal teeth serrated and well developed; two in the right valve, one in the left (occasionally with a small tooth on either side). Lateral teeth heavy, serrated, and straight to slightly curved; two in the left valve, one in the right. Beak cavity deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers in mud, sand, or gravel. Status Widespread and relatively common. Commercial species. Subfamily Ambleminae 39 Quadrula pustulosa, INHS 1 1704. Iroquois River, Kankakee County, Illinois. Length: 2.2 inches (5.6 cm). 40 Mussels of the Midwest Threeridge Amblema plicata (Say, 1817) Other common names Blue-point, purple-tip, fluter. Key characters Elongate or rounded shell with ridges or folds on the posterior half. No sculpturing on the anterior end, espe¬ cially near the umbo. Similar species Washboard, rock-pocketbook. Description Shell thick, elongate or rounded, and compressed to inflated. Anterior end rounded, posterior end rounded or bluntly pointed. Dorsal margin straight, ventral margin straight to curved. Umbos low, equal to or slightly elevated above the hinge line. Beak sculpture of three or four ridges usually seen only in young shells. Shell smooth on the anterior third, with three or more roughly parallel ridges or folds on the posterior two-thirds. Shells from large rivers generally more inflated and without as many folds or wrinkles as those found in smaller streams. Periostracum yellowish green, light brown, or green in juveniles, becoming dark green, brown, or black in older shells. Length to 7 inches (17.8 cm). Pseudocardinal teeth serrated and well developed; two in the left valve, one in the right (occasionally with a small tooth on either side). Lateral teeth serrated and straight to slightly curved; two in the left valve, one in the right. Beak cavity medium to deep. Nacre pearly white, frequently stained, iridescent posteri¬ orly. Some individuals with a purple tint on the posterior end. Habitat Small to large rivers and impoundments in mud, sand, or gravel. Status Widespread and common throughout most of its range. Apparently declining in some smaller streams. Commercial species. 42 Mussels of the Midwest Ebonyshell Fusconaia ebena (Lea, 1831) Other common names None. Key characters Round, heavy, thick, brown or black shell without rays or pustules. Beak cavity very deep. Similar species Long-solid, hickorynut, round hickorynut, ring pink, pigtoes ( Fusconaia and Pleurobema). Description Shell solid, heavy, rounded or oval, and inflated. Anterior end rounded, posterior end rounded or bluntly pointed. Dorsal margin slightly rounded, ventral margin curved, occasion¬ ally straight. Umbos low, inflated, about even with hinge line and curved downward. Beak sculpture consists of a few very weak ridges, apparent only in extremely small shells. Shell smooth with slightly elevated ridges indicating periods of growth. Periostracum rayless, light brown in young shells, becoming dark brown to black in older individuals. Length to 4 inches (10.2 cm). Pseudocardinal teeth very heavy and well developed; two in the left valve, two in the right. Lateral teeth serrated and curved; two in the left valve, one in the right. Beak cavity very deep. Nacre pearly white, iridescent posteriorly. Habitat Large rivers in sand and gravel. Status Endangered in Missouri and Wisconsin. Threatened in Ohio. Species of Special Concern in Illinois and Minnesota. Subfamily Ambleminae 43 Fusconaia ebena, INHS 2656. Ohio River, Pulaski County, Illinois. Length: 2.9 inches (7.4 cm). 44 Mussels of the Midwest Long-solid Fusconaia subrotunda (Lea, 1831) Other common names Round-solid, pigtoe. Key characters Smooth, elongate, and solid shell; beak cavity very deep, green rays on the umbo. Similar species Ebonyshell, pigtoes ( Fusconaia and Pleurobema). Description Shell relatively large, solid, elongate, oval or elliptical, and moderately inflated. Anterior end rounded, posterior end rounded or bluntly pointed. Dorsal margin and ventral margins straight to slightly curved. Umbos low and directed forward. Shell smooth, light brown, becoming dark brown to black in adults. Fine green rays present on juveniles and the umbos of older shells. Length to 5 inches (12.7 cm). Pseudocardinal teeth large and well developed; two in the left valve, one in the right (occasionally with a small tooth on either side). Lateral teeth large and straight; two in the left valve, one in the right. Beak cavity very deep. Nacre white, iridescent posteriorly. Habitat Large rivers in gravel. Status Endangered in Indiana and Ohio. Extirpated from Illinois. 46 Mussels of the Midwest Wabash pigtoe Fusconaia flava (Rafinesque, 1820) Other common name Pigtoe. Key characters Triangular shell with a shallow sulcus usually present on the side, rough clothlike periostracum, deep beak cavity. Similar species All other pigtoes (. Fusconaia and Pleurohema). Description Shell highly variable, moderately thick, triangular, and compressed (creeks and small rivers) to inflated (large rivers). Anterior end rounded, posterior end bluntly pointed. Dorsal margin straight, ventral margin curved anteriorly and straight or slightly arched posteriorly. Umbos low to moderately elevated and inflated. Beak sculpture of a few weak ridges apparent only in very small shells. A wide, shallow depression or sulcus usually present. Shell with a clothlike texture, yellowish brown, with faint green rays visible in young individuals, becoming chestnut or dark brown in older shells. Length to 3 inches (7.6 cm). Pseudocardinal teeth well developed, rough; two in the left valve, one in the right. Lateral teeth straight or slightly curved, serrated; two in the left valve, one in the right, occasionally with a second smaller lateral tooth. Beak cavity deep. Nacre white, or tinged with salmon, iridescent posteriorly. Habitat Creeks to large rivers in mud, sand, or gravel. Status Widespread and common. Subfamily Ambleminae 47 Fusconaia flava, INHS 1 1802. Mississippi River, Buffalo County, Wisconsin. Length: 2.4 inches (6.1 cm). 48 Mussels of the Midwest Purple wartyback Cyclonaias tuberculata (Rafinesque, 1820) Other common names Missouri mapleleaf, purple pimpleback, deerhorn. Key characters Rounded shell with a fairly prominent wing, beak covered with fine wavy sculpturing, no green stripe on the umbo, purple nacre. Deep and compressed beak cavity. Similar species Orange-foot pimpleback, pimpleback, mapleleaf, wartyback. Description Shell round, moderately thick, and compressed to moderately inflated (large rivers). Anterior end rounded, poste¬ rior end somewhat squared off. Dorsal margin straight, a wing present behind the umbo; ventral margin curved. Umbos low, even with, or barely rising above the hinge line. Beak sculpture of numerous wavy ridges covering the surface of the umbo. Shell surface, except the anterior fourth, covered with tubercles, forming small ridges on the dorsal wing. Periostracum yellowish brown or greenish brown in young shells (rarely rayed), becom¬ ing dark brown in older shells. Length to 5 inches (12.7 cm). Pseudocardinal teeth large and well developed; two in the left valve, one in the right (usually with a small tooth on either side). Lateral teeth short, striated, and straight or slightly curved; two in the left valve, one in the right. Beak cavity very deep. Nacre usually deep purple, occasionally white with a purple tinge. Habitat Medium to large rivers in gravel or mixed sand and gravel. Status Widespread but uncommon in most of the Midwest. Endangered in Wisconsin. Threatened in Iowa. Species of Special Concern in Michigan. Species of Special Interest in Ohio. Subfamily Ambleminae 49 Cyclonaias tuberculata , INHS 4078. Tippecanoe River, Fulton County, Indiana. Length: 3.5 inches (8.9 cm). 50 Mussels of the Midwest Sheepnose Plethobasus cyphyus (Rafinesque, 1820) Other common name Bullhead. Key characters Oblong shell with a smooth surface except for a single row of bumps or knobs running from the umbo to the ventral margin. Similar species White wartyback, threehom wartyback, round pigtoe, Wabash pigtoe, hickorynut. Description Shell thick, oval or oblong, somewhat elongate, and slightly inflated. Anterior end rounded, posterior end bluntly pointed. Dorsal margin straight, ventral margin curved anteriorly, straight posteriorly. Umbos slightly elevated above the hinge line. Beak sculpture of two heavy ridges, visible only in young shells. Shell smooth, except for a row of knobs or tubercles on the center of the valve, running from the umbo to the ventral margin (some¬ times obscure). A shallow sulcus or furrow present between the row of tubercles and the posterior ridge. Periostracum yellow or light brown in juveniles, becoming chestnut to dark brown in adults. Length to 5 inches (12.7 cm). Pseudocardinal teeth rather small relative to overall shell size; two in the left valve, one in the right (occasionally with a smaller tubercular tooth on either side). Lateral teeth long, straight or slightly curved; two in the left valve, one in the right. Beak cavity shallow. Nacre white, occasionally tinged with pink or salmon. Habitat Medium to large rivers in gravel or mixed sand and gravel. Status Rare throughout its range. Endangered in Indiana, Iowa, Ohio, and Wisconsin. Threatened in Illinois. Rare in Missouri. Subfamily Ambleminae 51 Plethobasus cyphyus, INHS 4179. Tippecanoe River, Pulaski County, Indiana. Length: 3.8 inches (9.7 cm). 52 Mussels of the Midwest White wartyback Plethobasus cicatricosus (Say, 1829) Other common names None. Key characters Oblong or elongate shell, light brown, with a row of large tear-shaped tubercles running down the side of the shell. Similar species Sheepnose, round pigtoe, hickorynut. Description Shell oblong, elongate, thick, and moderately inflated. Anterior end rounded, posterior end broadly rounded. Dorsal and ventral margins curved. Umbos low, directed forward, and not elevated above the hinge line. Shell smooth, except for a single row of large pustules or knobs on the center of the valve, running from below the umbo to the edge. Periostracum yellow or light brown in juveniles, becoming chestnut to dark brown in adults. Faint green rays present on the umbo. Length to 5 inches (12.7 cm). Pseudocardinal teeth large and well developed; two in the left valve, one in the right, with a smaller tooth on either side. Lateral teeth rather short, straight or slightly curved; two in the left valve, one in the right. Beak cavity relatively shallow. Nacre white, iridescent posteriorly. Habitat Large rivers in gravel. Status Federally Endangered. Most likely extirpated from the Midwest. 54 Mussels of the Midwest Orange-foot pimpleback Plethobasus cooperianus (Lea, 1834) Other common name Orange-footed pearlymussel. Key characters Round shell with pustules only on the posterior three-fourths of the shell. No green ray on the umbo. The live mussel has an orange foot. Similar species Pimpleback, purple wartyback. Description Shell thick, solid, round or slightly elongate, and moderately inflated to compressed. Anterior end rounded, posterior end rounded to bluntly pointed. Dorsal margin straight or slightly curved, ventral margin curved. Umbos low, directed forward, and only slightly elevated above the hinge line. Anterior fourth of the shell smooth, numerous pustules present on the posterior three-fourths. Periostracum rayless, light brown in small shells, becoming chestnut or dark brown color in larger individu¬ als. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right, with a smaller tooth on either side. Lateral teeth rather short, straight or slightly curved; two in the left valve, one in the right. Beak cavity very deep. Nacre white, usually with pink or salmon near the beak cavity, iridescent posteriorly. Habitat Large rivers in gravel or mixed sand and gravel. Status Federally Endangered. Still extant in the Ohio River. Subfamily Ambleminae 55 Plethobasus cooperianus, INHS 1 86. Cumberland River, Cumberland County, Kentucky. Length: 2.5 inches (6.4 cm). 56 Mussels of the Midwest Clubshell Pleurobema clava (Lamarck, 1819) Other common name Northern clubshell. Key characters A triangular shell with an elongated posterior end and green rays on umbo. Similar species Pyramid pigtoe, ellipse. Description Shell triangular, elongate, relatively thick, and compressed to moderately inflated. Anterior end rounded, posterior end bluntly pointed. Dorsal margin curved and slanted down toward the point of the shell, ventral margin straight to slightly curved. Umbos low, projected far forward and only slightly elevated above the hinge line. Beak sculpture when visible of a few sharp ridges at the tip of the umbo. Shell smooth, with an occasional crease or groove present on posterior lateral surface in some individuals. Periostracum yellowish brown with prominent broken green rays present in the umbo region on most specimens; older shells dark brown or black. Length to 3 inches (7.6 cm). Pseudocardinal teeth small and well developed; two in the left valve, one in the right. Lateral teeth moderately long, straight to slightly curved; two in the left valve, one in the right (occa¬ sionally with an additional shorter lateral tooth in the right valve). Beak cavity moderately deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers in gravel or mixed gravel and sand. Status Proposed for Federal Endangered status. Endangered in Illinois, Indiana, Michigan, and Ohio. Subfamily Ambleminae 57 Pleurobema clava, INHS 3545. Tippecanoe River, Fulton County, Indiana. Length: 1.9 inches (4.8 cm). 58 Mussels of the Midwest Round pigtoe Pleurobema coccineum (Conrad, 1836) Other common names Solid pigtoe, pink pigtoe, flat pigtoe, bullnose. Key characters A highly variable shell that is relatively large, rounded or elongate, chestnut or brown, with a shallow beak cavity. Similar species All other pigtoes ( Fusconaia and Pleurobema ), hickorynut, round hickorynut. Description Shell moderately thick, round, and compressed (medium-sized rivers) to inflated (large rivers). Anterior end rounded, posterior end rounded to bluntly pointed. Dorsal margin straight to slightly curved, ventral margin usually curved. Umbos low and only slightly elevated above the hinge line. Beak sculpture of two or three elevated ridges on the umbo. Shell smooth. Periostracum greenish brown, light brown, or reddish brown in juveniles, becoming chestnut or dark brown in adults, with faint green rays visible near the beaks in some shells. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth straight. Beak cavity shallow (medium-sized rivers) to moderately deep (large rivers). Nacre variable from white to pink or rose-colored. Habitat Medium to large rivers in mud, sand, or gravel. Status Widespread but usually uncommon. May be locally abundant in some drainages. Endangered in Iowa. Species of Special Interest in Ohio. Subfamily Ambleminae 59 Pleurobema coccineum , INHS 12110. Sangamon River, Champaign County, Illinois. Length: 3.1 inches (7.9 cm). 60 Mussels of the Midwest Rough pigtoe Pleurobema plenum (Lea, 1840) Other common name Pigtoe. Key characters Shell shaped like an equilateral triangle, with a brown, satinlike appearance and a moderately deep beak cavity. Similar species All other pigtoes ( Fusconaia and Pleurobema). Description Shell somewhat triangular, higher than long, moderately thick, and inflated. Anterior and posterior ends rounded. Dorsal and ventral margins curved. Umbos inflated and elevated above the hinge line. Beak sculpture of two or three elevated ridges. Shell textured, with a satin-like appearance. Periostracum yellowish brown or light brown in small shells, becoming dark brown in adults, with faint green rays visible near the beaks in some shells. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth straight. Beak cavity moderately deep. Nacre usually white, occasionally pink. Habitat Medium to large rivers in sand or gravel. Status Federally Endangered. Subfamily Ambleminae 61 Pleurobema plenum , INHS 13609. Barren River, Warren County, Kentucky. Length: 3.0 inches (7.6 cm). 62 Mussels of the Midwest Ohio pigtoe Pleurobema cordatum (Rafinesque, 1820) Other common name Pigtoe. Key characters Triangular shell, umbos projecting forward, sulcus present, deep beak cavity. Similar species All other pigtoes ( Fusconaia and Pleurobema). Description Shell moderately thick, triangular, and moderately inflated. Anterior end rounded, posterior end bluntly pointed. Dorsal margin straight, ventral margin curved anteriorly, straight posteriorly. Umbos moderately high and projecting forward. Beak sculpture of two or three elevated ridges. Shell smooth, a broad shallow sulcus present in front of the posterior ridge. Periostracum dark brown or chestnut, juveniles often lighter and marked with green rays, particularly near the beaks. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth straight to slightly curved. Beak cavity very deep. Nacre variable, usually white, occasionally pink or rose-colored in some individuals. Habitat Medium to large rivers in sand or gravel in areas with moderate flow. Status Widespread but sporadic in the Ohio River and its tributaries. Endangered in Ohio. Species of Special Concern in Illinois and Indiana. Subfamily Ambleminae Pleurobema cordatum, INHS 780. Wabash River, White County, Illinois. Length: 3.2 inches (8.1 cm). 64 Mussels of the Midwest Pyramid pigtoe Pleurobema rubrum (Rafinesque, 1820) Other common name Pink pigtoe. Key characters Triangular and elongate shell, shallow sulcus present, rose-colored nacre, moderately deep beak cavity. Similar species All other pigtoes ( Fusconaia and Pleurobema). Description Shell thick, triangular and elongate, and moderately inflated. Anterior end rounded, posterior end rounded to bluntly pointed. Dorsal and ventral margins curved. Umbos high, projected forward, and anterior to rest of shell. Shell smooth of satin-like. Shallow sulcus present. Periostracum brown or chestnut, with faint green rays on the umbos. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth straight or slightly curved. Beak cavity moderately deep. Nacre pink or rose-colored in most individuals, occasionally white. Habitat Medium to large rivers in sand or gravel in areas with a good current. Status Widespread but rare in the Ohio River drainage. Federal Candidate (Category 2). Endangered in Indiana and Ohio. Species of Special Concern in Illinois. Subfamily Ambleminae 65 Pleurobema rubrum , INHS 3122. Little Wabash River, Wayne County, Illinois. Length: 2.4 inches (6.1 cm). 66 Mussels of the Midwest Elephant-ear Elliptio crassidens (Lamarck, 1819) Other common names Mule’s ear, blue ham. Key characters Heavy, solid, and triangular shell with dark brown to black periostracum and light purple nacre. Similar species Spike, mucket. Description Shell thick, solid, compressed to moderately inflated, triangular. Anterior end rounded, posterior end pointed. Dorsal margin slightly curved, ventral margin curved in young shells, becoming straight in older shells. Umbos low, usually not elevated above the hinge line. Beak sculpture, if visible, of two or three loops parallel to the growth lines, usually present only in very small shells. Posterior ridge prominent and sharply angled. Surface of the shell smooth. Periostracum reddish brown with faint green rays in small shells, becoming dark brown to black in adults. Length to 6 inches (15.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth short, roughened, and straight. Beak cavity very shallow. Nacre color variable, usually purple, occasionally pink or white. Habitat Large rivers in mud, sand, or fine gravel. Status Widespread but relatively rare in the Midwest. Locally abundant in some parts of the Ohio and White rivers of Illinois and Indiana. Endangered in Missouri, Ohio, and Wisconsin. Threatened in Illinois. Species of Special Concern in Minnesota. Subfamily Ambleminae 67 Elliptio crassidens , INHS 2655. Ohio River, Pulaski County, Illinois. Length: 4.2 inches (10.7 cm). 68 Mussels of the Midwest Spike ElUptio dilatata (Rafinesque, 1820) Other common name Lady finger. Key characters Thick, elongate shell, short lateral teeth, greenish brown or black, usually with a purple nacre. Similar species Black sandshell, spectaclecase, elephant-ear, kidneyshell. Description Shell solid, elongate, elliptical, and compressed to moderately inflated. Anterior end rounded, posterior end rounded to slightly pointed. Dorsal margin straight to slightly curved, ventral margin straight to curved in young shells, becoming arched in older shells. Umbos low, usually not elevated above the hinge line. Beak sculpture, if visible, of three or four heavy loops. Surface smooth, greenish brown with faint green rays visible on small shells, becoming dark brown to black in adults. Length to 5 inches (12.7 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth short, roughened, and straight. Beak cavity very shallow. Nacre variable, most often purple, occasion¬ ally pink or white. Habitat Small to large streams and occasionally lakes in mud or gravel. Status Widespread but sporadic in distribution. Common in Missouri and Ohio, uncommon to rare in other states. Species of Special Concern in Illinois. Subfamily Ambleminae 69 Elliptio dilatata , INHS 8505. Big Kilbuck Creek, Madison County, Indiana. Length: 4.0 inches (10.2 cm). 70 Mussels of the Midwest Cracking pearlymussel Hemistena lata (Rafinesque, 1820) Other common names None. Key characters Thin, elongate shell, yellowish brown with broken green rays, poorly developed teeth, purple or pinkish nacre near the beak cavity. Similar species Fluted-shell, pondhom, yellow sandshell. Description Shell thin, elongate, and compressed. Anterior end rounded, posterior end pointed. Dorsal margin straight, ventral margin straight to slightly curved. Umbos low, not elevated above the hinge line. Beak sculpture of three or four weak ridges. Periostracum yellowish brown or tan with broken green rays on some shells. Length to 4 inches (10.2 cm). Teeth poorly developed. Pseudocardinal teeth as a thickened knob or ridge, one in each valve. Lateral teeth as a thickening of the hinge line. Beak cavity very shallow or absent. Nacre bluish white, with light purple or pink in the beak cavity area. Habitat Medium to large rivers in mud, sand, or gravel. Status Federally Endangered. Likely extirpated from the Midwest. Subfamily Ambleminae 71 Hemistena lata , UIMNH Z-3826. Duck River, Maury County, Tennes¬ see. Length: 2.8 inches (7.1 cm). 72 Mussels of the Midwest Pondhorn Uniomerus tetralasmus (Say, 1831) Other common name Horn shell. Key characters Relatively thin, smooth, elongate shell, light to dark brown, pointed, and rayless. Posterior slope with a short ridge formed by two shallow grooves on either side. Similar species Yellow sandshell, giant floater, cracking pearlymussel, cylindrical papershell, squawfoot. Description Shell relatively thin, elongate, and compressed to moderately inflated. Anterior end rounded, posterior end bluntly or sharply pointed. Dorsal margin straight, ventral margin straight, rarely curved. Umbos low, approximately even with the hinge line. Beak sculpture of four or five concentric ridges. Two shallow grooves present on the posterior slope, giving rise to a short ridge. Surface smooth and shiny in small shells, becoming rougher and dull in older individuals. Periostracum greenish or yellowish brown in young individuals, adults dark brown to black and rayless. Length to 5 inches (12.7 cm). Pseudocardinal teeth small and thin; two in the left valve, one in the right. Lateral teeth relatively thin, short, and straight to slightly curved. Beak cavity shallow. Nacre white, occasionally with a tinge of salmon. Habitat Ponds, small creeks, and the headwaters of larger streams in mud or sand. (This mussel can withstand periods of desiccation and is often present in areas where few other mussels are found.) Status Widespread but generally uncommon. May be abundant in its preferred habitat. Threatened in Ohio. Subfamily Ambleminae 73 Uniomerus tetralasmus , INHS 7807. Mississippi River, Perry County, Missouri. Length: 4.0 inches (10.2 cm). 74 Mussels of the Midwest Paper pondshell Utterbackia ( =Anodonta ) imbecillis (Say, 1829) Other common names Paper floater, papershell. Key characters Relatively small thin shell, flattened beaks, double-looped beak sculpture, without teeth. Similar species Cylindrical papershell, giant floater, squawfoot. Description Shell elongate, oblong, compressed in young, becoming inflated in older shells. Shell extremely thin, transpar¬ ent in young individuals. Anterior end rounded, posterior end somewhat pointed. Ventral margin straight to moderately rounded. Umbos well forward, flattened, not rising above the hinge line. Beak sculpture double-looped, with five or six fine, wavy ridges. Shell smooth, shiny, light yellow in young and on the umbo of adults, rest of shell brownish green, occasionally with fine green rays. Length to 4 inches (10.2 cm). Both valves without teeth, hinge line straight and thin. Beak cavities shallow or absent. Nacre white or bluish white and iridescent posteriorly. Habitat Ponds, lakes, and sluggish mud-bottomed pools of creeks and rivers. Status Widespread and locally abundant. Subfamily Anodontinae 75 Utterbackia ( =Anodonta ) imbecillis, INHS 7203. Flat Branch, Christian County, Illinois. Length: 2.4 inches (6.1 cm). 76 Mussels of the Midwest Flat floater Anodonta suborbiculata Say, 1831 Other common name Heelsplitter. Key characters Large, thin, nearly circular shell, double-looped beak sculpture, without teeth. Similar species Giant floater, paper pondshell. Description Shell large, thin, nearly circular, and compressed to slightly inflated in some individuals. Anterior and ventral margins broadly rounded, posterior end bluntly pointed. Dorsal margin flattened and nearly straight. Umbos low, flattened, not raised above the hinge line. Beak sculpture of three or four irregular or broken double-looped ridges. A small wing occasion¬ ally present behind the umbo. Shell smooth, shiny, yellow or yellowish green to dark brown, with fine green rays in some individuals. Length to 7 inches (17.8 cm). Both valves without teeth, hinge line only slightly thickened. Beak cavity large and very shallow. Nacre white or pinkish white and iridescent. Habitat Ponds, lakes, or sluggish mud-bottomed pools of creeks and rivers. Status Locally abundant in the floodplain lakes, sloughs, and oxbows of the Mississippi and Ohio rivers and their tributaries. Rare in Missouri. Species of Special Interest in Ohio. Subfamily Anodontinae 77 Anodonta suborbiculata , INHS 7854. Mississippi River, Randolph County, Illinois. Length: 5.0 inches (12.7 cm). 78 Mussels of the Midwest Giant floater Pyganodon ( =Anodonta ) grandis (Say, 1 829) Other common names Floater, stout floater, papershell, hogshell, slopbucket. Key characters Large, thin, elongate shell, beaks elevated above hinge, double-looped beak sculpture, without teeth. Similar species Flat floater, paper pondshell, squawfoot, cylindrical papershell. Description Shell extremely variable but usually large, some¬ what elliptical or elongate, and inflated. Shell extremely thin in young mussels, somewhat thicker in older individuals. Anterior end broadly rounded, posterior end bluntly pointed. Ventral margin straight or slightly curved. Umbos full, usually located in the anterior third of the shell but occasionally more toward the center in the large-river form (P. grandis var. corpulenta ), elevated above the hinge line. Beak sculpture of three to five double-looped ridges. Shell smooth, light yellow or yellowish green with rays visible in younger specimens, becoming dark green to brown in older shells. Length to 10 inches (25.4 cm). Valves without teeth, hinge line slightly thickened and curved. Beak cavity broad and shallow. Nacre variable and may be silvery white, cream, pink, salmon, or copper-colored. Habitat Typically, ponds, lakes, and sluggish mud-bottomed pools of creeks and rivers; can be found in a variety of other habitats as well. Status Widespread and common. Subfamily Anodontinae 79 Pyganodon ( =Anodonta ) grandis, INHS 10319. Lone Tree Creek, Champaign County, Illinois. Length: 5.1 inches (13.0 cm). 80 Mussels of the Midwest Cylindrical papershell Anodontoides ferussacianus (Lea, 1834) Other common name Cylinder. Key characters Thin shell, without teeth, fine V-shaped beak sculpture. Similar species Squawfoot, paper pondshell, giant floater. Description Shell thin, elongate, elliptical, and inflated in females and older males. Anterior end rounded, posterior end bluntly pointed. Ventral margin either slightly curved, straight to moderately arched, or pinched in the middle. Posterior ridge rounded, prominent, and swollen in females. Umbos small, in forward third of shell, only slightly raised above the hinge line. Beak sculpture of three or four very fine, V-shaped ridges. Shell smooth, shiny, yellowish green, green, or brown, lighter on the beaks, with fine green rays, more concentrated on the posterior half of the shell, may be absent in older shells. Length to 3 inches (7.6 cm). Both valves without teeth. Hinge line thin and straight to slightly curved. Beak cavity shallow. Nacre silvery or bluish white and iridescent posteriorly. Habitat Small creeks and the headwaters of larger streams in mud and sand. Status Widespread and locally abundant. Endangered in Missouri. Threatened in Iowa. Subfamily Anodontinae 81 Anodontoides ferussacianus, INHS 8851. Kickapoo Creek, McLean County, Illinois. Length: 2.5 inches (6.4 cm). 82 Mussels of the Midwest Squawfoot Strophitus undulatus (Say, 1817) Other common names Strange floater, sloughfoot, creeper. Key characters Elliptical to oval shell, thin to relatively thick, green, dark brown, or black, with pronounced beak sculpture and poorly developed hinge teeth. Nacre usually salmon to orange. Similar species Cylindrical papershell, giant floater, paper pondshell. Description Shell elliptical, moderately compressed, and thin when young, becoming somewhat inflated and thicker in adults. Anterior end rounded, posterior end bluntly pointed, occasionally truncated. Ventral margin straight to slightly curved. Umbos slightly elevated above the hinge line and located at least one- third from the anterior end. Beak sculpture of two or three pronounced V-shaped ridges. Shell smooth and shiny. Periostracum green with rays in juveniles, becoming chestnut, dark brown, and black in older individuals. Length to 4 inches (10.2 cm). Pseudocardinal and lateral teeth weakly developed and present only as thickened ridges. Hinge line curved past the umbo. Beak cavity moderately shallow. Nacre salmon or cream- colored, bluish white along the outer margin of the shell. Habitat Small to medium-sized streams and occasionally large rivers in mud, sand, or gravel. Status Widespread and common. Threatened in Iowa. r Subfamily Anodontinae 83 Strophitus undulatus , INHS 1509. North Fork Vermilion River, Vermilion County, Illinois. Length: 3.2 inches (8.1 cm). 84 Mussels of the Midwest Elktoe Alasmidonta marginata Say, 1818 Other common names None. Key characters Bright yellowish green shell with numerous dark green rays and spots; a sharply angled posterior ridge, poorly developed teeth, and heavy beak sculpture. Similar species Snuffbox, slippershell mussel, deertoe. Description Shell elongate, triangular, inflated, and relatively thin. Anterior end rounded, posterior end sharply angled, ending in a blunt, squared point. Posterior ridge sharply angled and prominent, posterior slope broad, flat, and covered with fine ridges. Ventral margin straight to slightly curved. Umbos large, located near the center of the shell, and elevated above the hinge line. Beak sculpture of three or four heavy, double-looped ridges. Shell smooth and dull. Periostracum yellowish green or bright green with numerous rays and dark green spots present. Posterior slope often lighter than rest of shell. Length to 4 inches (10.2 cm). Pseudocardinal teeth thin and elongate; one in right, occa¬ sionally two in the left. Lateral teeth reduced to a thickened swelling along the hinge line. Beak cavity moderately deep. Nacre bluish white, occasionally with salmon near the beaks. Habitat Medium-sized streams in gravel or mixed sand and gravel. Status Widespread but sporadic in distribution. Threatened in Iowa. Subfamily Anodontinae 85 Alasmidonta marginata , INHS 1 1754. Blackberry Creek, Kendall County, Illinois. Length: 2.8 inches (7.1 cm). 86 Mussels of the Midwest Slippershell mussel Alasmidonta viridis (Rafinesque, 1820) Other common names None. Key characters Small, somewhat rectangular shell, high posterior ridge, wavy green rays on posterior half of the shell, poorly developed lateral teeth. Similar species Elktoe. Description Shell small (usually about an inch), somewhat inflated, thin in young individuals to moderately thick in adults. Anterior end rounded, posterior end squared or truncated. Posterior ridge high and rounded, posterior slope flattened. Ventral margin straight or slightly arched. Umbos full and elevated above the hinge line. Beak sculpture of three or four elevated ridges or loops. Shell smooth to rough and yellowish green with numerous wavy green rays, particularly on the posterior half of the shell. Length to 1.5 inches (3.8 cm). Pseudocardinal teeth triangular; two in the left valve, one in the right. Lateral teeth poorly developed, generally appearing as a slight swelling along the hinge line. Beak cavity moderately deep. Nacre white, iridescent on the posterior third of the shell. Habitat Creeks and the headwaters of large rivers in sand, mud, or fine gravel. Status Endangered in Illinois and Iowa. Threatened in Wisconsin. Subfamily Anodontinae 87 Alasmidonta viridis, INHS 7866. Baker Creek, Kankakee County, Illinois. Length: 1.4 inches (3.6 cm). 88 Mussels of the Midwest Rock-pocketbook Arcidens confragosus (Say, 1829) Other common names Rockshell, grandmaw, bastard, black pocketbook, queen. Key characters Large, relatively thin shell, heavily sculptured, with poorly developed lateral teeth. Similar species Threeridge, washboard. Description Shell thin to moderately thick, elliptical, and inflated. Anterior end rounded, posterior end squared or bluntly pointed. Ventral margin straight or slightly rounded. Umbos full, elevated above the hinge line and located near the middle of the shell. Beak sculpture of large pronounced knobs or double- looped ridges that continue to the edge of the shell in two rows, developing into folds on the surface. Periostracum dark green, brown, or black. Length to 7 inches (17.8 cm). Pseudocardinal teeth compressed, elongate; two in the left valve, one in the right. Poorly developed lateral teeth, often present only as a finely serrated thickening of the hinge line. Beak cavity moderately deep. Nacre white, iridescent on the posterior third. Habitat Medium to large rivers in pools and areas of reduced flow in mud and sand. Status Extirpated from Ohio. Threatened in Wisconsin. Rare in Missouri. Uncommon to rare in the other states of the Midwest. Subfamily Anodontinae 89 Arcidens confragosus, INHS 9459. Mississippi River, Louisa County, Iowa. Length: 2.8 inches (7.1 cm). 90 Mussels of the Midwest Salamander mussel Simpsonaias ambigua (Say, 1825) Other common names Simpson’s shell, smooth minishell. Key characters Small, thin, elliptical shell, poorly developed teeth, double-looped beak sculpture, rayless. Similar species Cylindrical papershell, spectaclecase, pondhom. Description Shell small, thin, elongate elliptical or oval, and compressed (male) to slightly inflated posteriorly (female). Anterior and posterior ends rounded. Posterior ridge rounded. Dorsal and ventral margins straight, parallel. Umbos slightly elevated above the hinge line. Beak sculpture of three or four double-looped bars. Shell smooth, dull, yellowish tan to dark brown, and rayless. Length to 2 inches (5.1 cm). Pseudocardinal teeth very small, low, rounded; one in each valve. Lateral teeth absent. Beak cavity shallow. Nacre bluish white, occasionally tinged with salmon near the beaks, iridescent on the posterior half. Habitat Medium to large rivers on mud or gravel bars and under flat slabs or stones. Status Federal Candidate (Category 2). Endangered in Illinois, Michigan, and Missouri. Threatened in Wisconsin. Species of Special Concern in Indiana. Species of Special Interest in Ohio. Subfamily Anodontinae 91 Simpsonaias ambigua , UIMNH Z-3838. Kankakee River, Will County, Illinois. Length: 1.8 inches (4.6 cm). 92 Mussels of the Midwest White heeisplitter Lasmigona complanata (Bames, 1823) Other common names Pancake, razorback, elephant-ear, hackle-back. Key characters Large, rounded, compressed, relatively thin shell, bluntly pointed at the posterior end; dark brown or black periostracum, double-looped beak sculpture, and white nacre. Similar species Pink heeisplitter, creek heeisplitter. Description Shell large, rounded, and compressed, very thin in young individuals, becoming slightly thicker in adults. Anterior end rounded, posterior end rounded to bluntly pointed. Dorsal margin straight with a large wing, often with several folds or ridges that extend to the side of the shell. Ventral margin straight to slightly curved. Umbos small, flattened, not projecting above the hinge line. Beak sculpture of four to six distinct, double- looped bars. Shell smooth except on the wing. Periostracum green or greenish brown in young shells, often faintly rayed, dark brown to black in old shells. Length to 8 inches (20.3 cm). Pseudocardinal teeth well developed; two in the left valve, one (occasionally two) in the right. Lateral teeth poorly devel¬ oped in both valves, represented as ridges or thickenings of the hinge line. Beak cavity shallow to moderately deep. Nacre bluish white or white, iridescent posteriorly. Habitat Pools or sluggish streams with a mud, sand, or fine gravel bottom. Status Widespread and common. Subfamily Anodontinae 93 Lasmigona complanata, INHS 13190. Sugar Creek, Boone County, Indiana. Length: 3.5 inches (8.9 cm). 94 Mussels of the Midwest Fluted-shell Lasmigona costata (Rafinesque, 1820) Other common names Sand mussel, squawfoot. Key characters Elongate, compressed shell with prominent ridges or folds (flutings) on the posterior slope and poorly developed lateral teeth (paired in the left valve). Similar species Creek heelsplitter. Description Shell elongate, moderately thick, and compressed to slightly inflated. Anterior and posterior ends sharply curved. Dorsal and ventral margins straight. Umbos low, not projecting above the hinge line. Beak sculpture of three or four heavy, more or less double-looped ridges parallel with the hinge line. Promi¬ nent sculpturing on the posterior slope consisting of about 10-20 heavy, rounded ridges of folds. Additional surface sculpturing on the lateral surface near the middle of the shell. Periostracum green or yellowish green with numerous green rays in small individuals, becoming chestnut or dark brown in older shells. Length to 7 inches (17.8 cm). Pseudocardinal teeth thick; two in the left valve, one (occasionally two) in the right. Lateral teeth short and poorly developed, often appearing only as ridges or thickenings of the hinge line. Beak cavity shallow. Nacre white or bluish white and often salmon-colored, particularly in the beak cavities. Habitat Medium to large rivers in sand, mud, or fine gravel in areas with slow to moderate flow. Status Widespread but relatively uncommon. Endangered in Iowa. Subfamily Anodontinae 95 Lasmigona costata , INHS 1 162. Sangamon River, Champaign County, Illinois. Length: 4.1 inches (10.4 cm). 96 Mussels of the Midwest Creek heelsplitter Lasmigona compressa (Lea, 1829) Other common names None. Key characters Relatively thin, elongate shell, well-developed lateral teeth, prominent flattened posterior ridge, double-looped beak sculpture. Similar species Fluted-shell, white heelsplitter. Description Shell small to medium-sized, elongate, relatively thin, and compressed. Anterior end broadly rounded, posterior end bluntly pointed and squared at the tip. Posterior ridge prominent and broadly flattened with a small wing behind the umbo, usually more evident in small shells. Dorsal margin straight, ventral margin rounded, occasionally straight. Umbos projecting slightly above the hinge line. Beak sculpture of five to eight double-looped ridges. Shell smooth and yellowish brown with numerous green rays in young individuals, becoming darker green or brown in older shells. Length to 4 inches (10.2 cm). Pseudocardinal teeth well developed; two in the left valve, one in the right. Lateral teeth short, thin, and finely serrated; two in the left valve, one in the right. Beak cavity very shallow. Nacre white to salmon-colored, especially near the beak cavities. Habitat Creeks and the headwaters of small to medium rivers in fine gravel or sand. Rarely found in larger rivers. Status Widespread but uncommon. Threatened in Illinois and Iowa. 98 Mussels of the Midwest Kidneyshell Ptychobranchus fasciolaris (Rafinesque, 1820) Other common names None. Key characters Thick, kidney-shaped shell, heavy teeth, yellowish brown, with broken green rays. Similar species Spike, mucket, ellipse, rainbow. Description Shell solid, thick, elongate, compressed, and kidney-shaped. Anterior end rounded, posterior end bluntly pointed. Dorsal margin straight to slightly curved, ventral margin curved, straight, or arched. Umbos low, approximately even with the hinge line. Beak sculpture, if visible, of two or three indistinct ridges. Shell smooth. Periostracum yellowish brown to brown with broad green rays, usually interrupted or broken. Length to 6 inches (15.2 cm). Pseudocardinal teeth thick and triangular; two in the left valve, one in the right, sometimes with a low, roughened tubercu¬ lar tooth on either side. Lateral teeth short, nearly straight, heavy, and serrated. Beak cavity shallow or absent. Some females with a fold or groove on the inside. Nacre pearly white. Habitat Medium to large rivers in gravel. Status Fairly widespread but only locally abundant. Disappear¬ ing from parts of its range. Endangered in Illinois. Subfamily Lampsilinae 99 Ptychobranchus fasciolaris, INHS 3475. Tippecanoe River, Fulton County, Indiana. Length: 4.5 inches (1 1 .4 cm). 100 Mussels of the Midwest Threehorn wartyback Obliquaria reflexa Rafinesque, 1820 Other common names Homyback, three dot, three knot. Key characters The large knobs that alternate from side to side will distinguish this mussel from all other species found in the Midwest. Similar species Pimpleback, sheepnose, tubercled blossom. Description Shell usually small, rounded, moderately thick, and inflated. Anterior end rounded, posterior end bluntly pointed. A row of three or four large, elevated knobs extending from the beak to the center of the ventral margin, with the knobs alternat¬ ing in position with those of the other side. Often a broad depression present between the knobs. Beaks elevated and curved inward. Periostracum highly variable in color from light yellow¬ ish brown to green and dark brown. Shell usually covered with numerous fine, dark green, broken rays. Length to 3 inches (7.6 cm). Pseudocardinal teeth heavy and serrated; two in the left valve, one in the right. Lateral teeth straight to slightly curved, short, and serrated. Beak cavity shallow to moderately deep. Nacre pearly white. Habitat Large rivers in sand or gravel; may be locally abundant in impoundments. Status Widespread and common in the large rivers of the Midwest. Threatened in Ohio. Subfamily Lampsilinae 101 Obliquaria reflexa, INHS 3052. Rock River, Rock Island County, Illinois. Length: 2.2 inches (5.6 cm). 102 Mussels of the Midwest Fanshell Cyprogenia stegaria (Rafinesque, 1820) Other common names Eastern fanshell, Ohio fanshell, pimpleback, ringed wartyback. Key characters Rounded shape, numerous pustules, elevated growth lines, broken green rays. Similar species Pimpleback, purple pimpleback. Description Shell rounded, solid, and moderately inflated. Anterior margin rounded, posterior margin bluntly rounded or truncated. Ventral margin broadly rounded. Umbos not elevated above the hinge line. Beak sculpture, if visible, of a few weak ridges. Growth lines appear as distinct elevated ridges. Numerous pustules usually concentrated in the center but occasionally covering the entire surface of the shell. Periostracum usually greenish yellow, with a pattern of dark green rays made up of numerous smaller broken lines or dots. Length to 3 inches (7.6 cm). Pseudocardinal teeth relatively large and serrated; two in the left valve, one in the right. Lateral teeth roughened, straight to slightly curved, heavy and very short. Interdentum wide. Beak cavity shallow to moderately deep. Nacre white, iridescent posteriorly. Habitat Medium to large rivers in gravel riffles. Status Federally Endangered. Subfamily Lampsilinae 103 Cyprogenia stegaria, UIMNH Z- 14954. Wabash River, Posey County, Indiana. Length: 1.9 inches (4.8 cm). 104 Mussels of the Midwest Mucket Actinonaias ligamentina (Lamarck, 1819) Other common names Grass mucket, brass mucket, steamboat mucket. Key characters Relatively large, oblong, thick shell, yellowish brown, with green rays and a relatively shallow beak cavity. Similar species Plain pocketbook, fatmucket, Higgins eye, pink mucket, elephant-ear, ellipse, hickorynut. Description Shell large, elliptical or oblong, thick, usually heavy, and compressed to moderately inflated. Anterior end rounded, posterior end bluntly pointed. Umbos slightly elevated above the hinge line. Beak sculpture of a few fine, double-looped ridges, usually visible only in young shells. Periostracum smooth, yellowish brown, with numerous green rays. Large shells dark brown with faint green rays or rayless. Length to 7 inches (17.8 cm). Pseudocardinal teeth large, slightly elevated and serrated; two in the left valve, one in the right. Lateral teeth straight to slightly curved, thin, and moderately long. Beak cavity shallow to moderately deep. Nacre white, occasionally tinged with pink or salmon, iridescent posteriorly. Habitat Medium to large rivers in gravel or mixed sand and gravel. Status Widespread and locally abundant. Extirpated from Ohio. Subfamily Lampsilinae Actinonaias ligamentina , INHS 13303. Iroquois River, Kankakee County, Illinois. Length: 3.6 inches (9.1 cm). 106 Mussels of the Midwest Butterfly Ellipsaria lineolata (Rafinesque, 1820) Other common names None. Key characters Triangular, flattened shell, sharply angled posterior ridge, yellowish brown, with broken brown rays. Similar species Deertoe. Description Shell somewhat triangular, thick, solid, and compressed. Anterior end broadly rounded, posterior end pointed. Umbos compressed, directed forward, and not elevated above the hinge line. Posterior ridge sharply defined. Lateral surfaces broadly flattened, less so in older females. Beak sculpture, if visible, of a few fine, double-looped ridges. Shell smooth, yellow or yellowish green, with scattered brown rays that are usually broken into V-shaped or irregular rectangular blotches. Old shells with faint brown rays or rayless. Length to 4 inches (10.2 cm). Pseudocardinal teeth relatively large, slightly elevated, serrated, and divergent; two in the left valve, one in the right. Usually two lateral teeth in each valve, serrated, short, and straight. Interdentum wide. Beak cavity shallow to moderately deep. Nacre white, iridescent posteriorly. Habitat Large rivers in sand or gravel. Status Widespread but only locally abundant. Disappearing from many areas where it formerly occurred. Endangered in Ohio and Wisconsin. Threatened in Iowa. Species of Special Concern in Illinois. Subfamily Lampsilinae 107 Ellipsaria lineolata , INHS 3046. Rock River, Rock Island County, Illinois. Length: 2.5 inches (6.4 cm). 108 Mussels of the Midwest Hickorynut Obovaria olivaria (Rafinesque, 1820) Other common names Eggshell, chestnut shell, glassyback. Key characters A thick, rounded or oblong shell with a smooth surface, greenish or yellowish brown, shallow beak cavity. Similar species Round hickorynut, round pigtoe, ring pink, ebonyshell, Higgins eye, mucket. Description Shell oval or oblong, thick, solid, and inflated. Anterior and posterior ends broadly rounded. Umbos slightly elevated above the hinge line, rounded, curved inward, and directed forward. Beak sculpture of four or five delicate, double- looped bars, usually evident only in very small shells. Shell smooth, olive green or yellowish brown, faintly rayed in young shells, becoming dark brown in old individuals. Length to 4 inches (10.2 cm). Pseudocardinal teeth triangular, relatively small, widely divergent, and horizontal. Lateral teeth straight to slightly curved, wide, heavy, and fairly long. Interdentum narrow. Beak cavity shallow. Nacre white, iridescent posteriorly. Habitat Large rivers (rarely in medium or small streams) in sand or mixed sand and gravel. Status Widespread and common in the Wabash and lower Ohio rivers but disappearing in the Mississippi and upper Ohio rivers. Endangered in Ohio. Species of Special Concern in Michigan. Watch List in Missouri. Subfami ly Lamps i li nae 109 Obovaria olivaria, INHS 6124. Wabash River, Fountain County, Indiana. Length: 3.0 inches (7.6 cm). 110 Mussels of the Midwest Round hickorynut Obovaria subrotunda (Rafinesque, 1820) Other common names None. Key characters Almost perfectly round, relatively small shell, with a smooth, brown, ray less periostracum. Similar species Hickorynut, round pigtoe, ebonyshell. Description Shell round or circular, moderately thick, and inflated. Anterior and posterior ends rounded in males, somewhat truncated in females. Umbos low and centrally placed, slightly elevated above the hinge line. Beak sculpture of a few indistinct, concentric ridges, usually evident only on very young shells. Shell smooth, growth lines dark but often indistinct. Periostracum yellowish brown to dark chestnut brown or blackish, and rayless. Length to 3 inches (7.6 cm). Pseudocardinal teeth moderately small, serrated, and divergent. Lateral teeth slightly curved, fairly short, and moder¬ ately thin. Interdentum narrow or absent. Beak cavity fairly deep. Nacre white, iridescent posteriorly. Habitat Medium-sized streams in sand and gravel in areas with moderate flow. Status Sporadic in distribution, disappearing from many areas. Endangered in Illinois and Michigan. Subfamily Lampsilinae 111 Obovaha subrotunda , INHS 4083. Tippecanoe River, Fulton County, Indiana. Length: 2.1 inches (5.3 cm). 112 Mussels of the Midwest Ring pink Obovaria retusa (Lamarck, 1819) Other common name Golf stick. Key characters Thick shell, recurved umbos, brown periostracum, nacre purple inside the pallial line. Similar species Ebonyshell, round pigtoe, round hickorynut, hickorynut. Description Shell thick, solid, and somewhat inflated, with an unusual dorso-ventrally elongated recurved shape. Anterior, ventral, and posterior margins rounded. Umbos high, full, swollen, and directed forward. Shell surface smooth or clothlike. The female has a distinct groove on the posterior ridge. Periostracum reddish brown, occasionally dark brown or black¬ ish. Length to 3 inches (7.6 cm). Pseudocardinal teeth large, elevated, heavy, and serrated; two in the left valve, one large one in the right, often with a smaller tooth on either side. Lateral teeth short, straight to slightly curved, and serrated. Interdentum moderately wide. Beak cavity deep. Nacre pink or purple within the pallial line, white around the margins. Habitat Large rivers in gravel or sand. Status Lederally Endangered. Extirpated from the Midwest. Subfamily Lampsilinae 113 Obovaria retusa , UIMNH Z- 14979. Wabash River, Posey County, Indiana. Length: 2.0 inches (5.1 cm). 114 Mussels of the Midwest Deertoe Truncilla truncata Rafinesque, 1820 Other common name Deerhom. Key characters Triangular shell, sharply angled posterior ridge, inflated, yellow, green, or brown, usually with numerous green rays. Similar species Fawnsfoot, butterfly, Wabash pigtoe, elktoe. Description Shell triangular, thin to moderately thick, and somewhat inflated. Anterior end rounded, posterior end bluntly pointed or truncated. Posterior ridge sharply angled. Umbos full and elevated well above the hinge line. Beak sculpture of three to five fine, double-looped ridges. Periostracum highly variable in color from yellow, green, yellowish brown to dark brown, with numerous green rays of variable widths and shape, often com¬ posed of fine broken lines or V-shaped or zigzag markings; occasionally rayless. Length to 2 inches (5.1 cm). Pseudocardinal teeth well developed, elevated and divergent; two in the left valve, one in the right. Lateral teeth straight to slightly curved, high, roughened, occasionally with an incom¬ plete, smaller inner lateral developed. Interdentum narrow or absent. Beak cavity shallow to moderately deep. Nacre white, occasionally pink, iridescent posteriorly. Habitat Medium to large rivers in mud, sand, or gravel. Status Widespread and common throughout much of its range. Species of Special Interest in Ohio. Subfamily Lampsilinae 115 Truncilla truncata, INHS 4568. Sangamon River, Piatt County, Illinois. Length: 2.0 inches (5.1 cm). 116 Mussels of the Midwest Fawnsfoot Truncilla donaciformis (Lea, 1828) Other common name Little pocketbook. Key characters Small, elongate shell, greenish yellow, with zigzag markings. Similar species Deertoe, rayed bean. Description Shell small, elongate, somewhat oblong, relatively thin, and compressed to moderately inflated. Anterior end rounded, posterior end pointed, ventral margin smoothly rounded. Umbos full, centrally located, and slightly elevated above the hinge line. Beak sculpture of five or six double-looped bars. Periostracum variable from yellow to greenish brown, with numerous dark green rays made up of many smaller broken, Y-¬ shaped or zigzag lines. Length to 2 inches (5.1 cm). Pseudocardinal teeth small, roughened, and elevated; two in the left valve, one in the right. Lateral teeth thin, relatively long, and straight to slightly curved. Beak cavity moderately shallow. Nacre white, iridescent posteriorly. Habitat Large rivers or the lower reaches of medium-sized streams in sand or gravel. Status Widespread and common throughout most of its range. Threatened in Ohio. Subfamily Lampsilinae 117 Truncilla donaciformis, INHS 3060. Rock River, Rock Island County, Illinois. Length: 1.6 inches (4.1 cm). 118 Mussels of the Midwest Scaleshell Leptodea leptodon (Rafinesque, 1820) Other common name Narrow papershell. Key characters A thin, elongate, compressed shell, yellowish green or brown, with fine green rays, pointed posterior end, poorly developed pseudocardinal teeth, and very fine lateral teeth. Similar species Fragile papershell. Description Shell relatively small, elongate, thin, and com¬ pressed. Anterior end rounded, posterior end pointed. Dorsal margin straight, ventral margin straight to broadly curved. Umbos small and low, about even with the hinge line. Beak sculpture, if visible, of four or five double-looped ridges. Shell smooth, yellowish green or brown, with numerous faint green rays. Length to 4 inches (10.2 cm). Pseudocardinal teeth reduced to a small thickened ridge. Lateral teeth moderately long; two low, indistinct lateral teeth in left valve, one fine tooth in the right. Beak cavity very shallow or absent. Nacre pinkish white or light purple and highly iridescent. Habitat Large rivers in mud. Status Federal Candidate (Category 2). Extirpated from Ohio. Likely extirpated from Illinois, Iowa, and Indiana. Rare in Missouri. Species of Special Concern in Michigan. Subfamily Lampsilinae 119 Leptodea leptodon, UIMNH Z- 14296. Wabash River, Vigo County, Indiana. Length: 3.5 inches (8.9 cm). 120 Mussels of the Midwest Fragile papershell Leptodea fragilis (Rafinesque, 1820) Other common names Papershell, cottonmouth. Key characters Thin, fragile, elongate shell, yellow or yellow¬ ish green with faint green rays, rounded posterior end, pinkish white and iridescent nacre. Similar species Scaleshell, pink papershell. Description Shell somewhat oblong, thin, and compressed. Anterior end rounded, posterior end rounded in males and broadly expanded in females. Dorsal wing present in young shells, becoming greatly reduced or absent in older individuals. Umbos flattened and only slightly elevated above the hinge line. Beak sculpture of three or four faint, double-looped bars. Shell smooth, shiny to dull, yellow or yellowish green, usually with numerous light green, indistinct rays; some rayless. Length to 6 inches (15.2 cm). Pseudocardinal teeth small, reduced to a thin ridge in small shells, becoming a thickened swelling in older shells; two in the left valve, one in the right. Lateral teeth long, thin, and com¬ pressed; two in the left valve, one in the right. Beak cavity shallow or absent. Nacre pinkish white or pink and highly iridescent. Habitat Streams of all sizes in mud, sand, or gravel. Status Widespread and common. Subfamily Lampsilinae 121 Leptodea fragilis, INHS 8019. Henderson Creek, Henderson County, Illinois. Length: 4.8 inches (12.2 cm). 122 Mussels of the Midwest Pink papershell Potamilus ohiensis (Rafinesque, 1820) Other common names Papershell, fragile heelsplitter. Key characters Thin, shiny, elongate and compressed shell, tan or olive green to dark brown, with pink to purple nacre. Similar species Fragile papershell, pink heelsplitter. Description Shell elongate, thin, fragile, and compressed. Anterior and posterior ends rounded. A large wing present behind the umbo, with a smaller wing in front, but often missing in older shells. Umbos flattened and not elevated above the hinge line. Beak sculpture of three or four small, thickened ridges. Shell very shiny, rayless, tan or olive green to dark brown (dark brown particularly in older shells). Length to 7 inches (17.8 cm). Pseudocardinal teeth thin, elongate, and slightly roughened; one in the left valve, two in the right. Lateral teeth long, thin, elevated, and straight or slightly curved. Beak cavity shallow. Nacre typically light purple, occasionally pink, and highly iridescent. Habitat Medium to large rivers in silt, mud, or sand. Status Widespread and locally common. Subfamily Lampsilinae 123 Potamilus ohiensis, INHS 2197. Kankakee River, Will County, Illinois. Length: 4.0 inches (10.2 cm). 124 Mussels of the Midwest Pink heelsplitter Potamilus alatus (Say, 1817) Other common names Purple heelsplitter, pancake, hatchet- back. Key characters An elongate and rectangular shell, well- developed posterior wing, dark green to dark brown, with a purple or pink nacre. Similar species Bleufer, white heelsplitter, pink papershell. Description Shell large, elongate, laterally compressed and somewhat rectangular, thin in young shells to moderately thick in older individuals. Anterior end rounded, posterior end bluntly squared or truncated. Umbos flattened and only slightly elevated above the hinge line. Beak sculpture of three or four concentric ridges, visible only in small shells. Large wing present posterior to the umbos. Shell smooth, dark green or brown, becoming black in old individuals. Young shells typically marked with dark green rays that become fainter with age. Length to 8 inches (20.3 cm). Pseudocardinal teeth small, roughened, thin and divergent; two in the left valve, two in the right. Lateral teeth long, thin, and straight to slightly curved. Beak cavity shallow. Nacre usually purple or pinkish purple, rarely white; highly iridescent. Habitat Medium to large rivers in mud or mixed mud, sand, and gravel. Status Widespread and relatively common. Subfamily Lampsilinae 125 Potamilus alatus, INHS 8049. Mackinaw River, McLean County, Illinois. Length: 3.8 inches (9.7 cm). 126 Mussels of the Midwest Bleufer Potamilus purpuratus (Lamarck, 1819) Other common names Blooper, blue mucket, blue hen, purple pocketbook. Key characters An elongate and rectangular shell, inflated, dark green to black, with a purple or pink nacre. Similar species Pink heelsplitter. Description Shell rectangular, moderately to greatly inflated, thin in young to moderately thick in older individuals. Anterior end rounded, posterior end bluntly squared or truncated. Umbos flattened, only slightly elevated above the hinge line. A low wing may be present behind the umbo. Beak sculpture of three or four double-looped ridges, visible only in young shells. Shell smooth, brown, becoming black in old individuals. Young mussels typically marked with dark green rays that become fainter with age. Length to 8 inches (20.3 cm). Pseudocardinal teeth small, roughened and divergent; two in the left valve, two in the right. Lateral teeth long, thin, and curved. Beak cavity shallow. Nacre deep purple and highly iridescent. Habitat Large rivers in mud or mixed mud and gravel. Status A southern species rarely found above the confluence of the Mississippi and Ohio rivers. Species of Special Concern in Illinois. Subfamily Lampsilinae Potamilus purpuratus, INHS 12852. Mississippi River, Fulton County, Kentucky. Length: 4.1 inches (10.4 cm). 128 Mussels of the Midwest Fat pocketbook Potamilus capax (Green, 1832) Other common names Pocketbook, grandmaw. Key characters A rounded, greatly inflated shell, thin to moderately thick, S-shaped hinge line, tan or light brown, rayless, and shiny. Similar species Plain pocketbook, pocketbook. Description Shell round to somewhat oblong, greatly inflated, and thin (young) to moderately thick (adults). Anterior and posterior ends rounded. Umbos greatly inflated, elevated, and turned inward. Beak sculpture of a few faint ridges, visible only in young shells. Small posterior wing present in young mussels. Surface usually smooth and very shiny. Periostracum rayless, yellow, yellowish tan, or olive, becoming dark brown in older individuals. Length to 5 inches (12.7 cm). Pseudocardinal teeth thin, compressed, and elevated; two in each valve. Lateral teeth thin and greatly curved; two in the left valve, one in the right. Hinge line S-shaped. Beak cavity very deep. Nacre white, sometimes tinged with pink or salmon. Habitat Large rivers in slow-flowing water in mud or sand. Status Federally Endangered. Subfamily Lampsilinae 129 Potamilus capax, INHS 8290. Wabash River, Posey County, Indiana. Length: 4.5 inches (1 1.4 cm). 130 Mussels of the Midwest Lilliput Toxolasma parvus (Bames, 1823) Other common names None. Key characters Small shell, usually no more than an inch long, elliptical or cylindrical, dark green or brown, with a clothlike texture. Similar species Purple lilliput, Texas lilliput, little spectaclecase. Description Shell small, elliptical or cylindrical, relatively solid, and inflated. Anterior and posterior ends rounded. Umbos inflated and slightly elevated above the hinge line. Beak sculpture consists of five or six distinct angled ridges. Surface of the shell with a clothlike texture, dark green, brown, or dark brown and rayless. Length to 1.5 inches (3.8 cm). Pseudocardinal teeth thin, elevated, compressed, and serrated; two in the left valve, one or two in the right. Lateral teeth long, thin and straight; two in the left valve, one in the right. Beak cavity moderately deep. Nacre silvery or bluish white and highly iridescent. Habitat Ponds, lakes, and creeks to large rivers in mud, sand, or fine gravel. Status Widespread and locally abundant. Subfamily Lampsilinae 131 Toxolasma parvus, INHS 10134. Otter Creek, LaSalle County, Illinois. Length: 1.2 inches (3.0 cm). 132 Mussels of the Midwest Purple lilliput Toxolasma lividus (Rafinesque, 1831) Other common name Little purple. Key characters A small, slightly elongate shell, dark brown, pointed or truncated on the posterior end, with a purple nacre. Similar species Lilliput, Texas lilliput, little spectaclecase. Description Shell small, rounded to somewhat oblong, rela¬ tively solid, and inflated. Anterior end rounded, posterior end bluntly pointed (males) or truncated (females). Umbos inflated and slightly elevated above the hinge line. Beak sculpture of three or four heavy bars. Periostracum tan or dark green to dark brown, becoming black in older shells. Length to 1 inch (2.5 cm). Pseudocardinal teeth well developed, elevated and serrated; two in the left valve, one in the right. Lateral teeth straight to slightly curved; two in the left valve, one in the right. Beak cavity variable from very shallow to moderately deep. Nacre purple, usually lighter near the ventral margin, and iridescent. Habitat Lakes and small to medium streams in gravel. Status Federal Candidate (Category 2). Endangered in Illinois, Michigan, and Ohio. Watch List in Missouri. i Subfamily Lampsilinae 133 Toxolasma lividus, UIMNH Z- 14295. Tippecanoe Lake, Kosciusko County, Indiana. Length: 1.2 inches (3.0 cm) for both male (top) and female (bottom). 134 Mussels of the Midwest Texas lilliput Toxolasma texasensis (Lea, 1857) Other common names None. Key characters Small shell, pointed or truncated on the poste¬ rior end, and greenish brown or black with a clothlike texture. Similar species Lilliput, purple lilliput, little spectaclecase, pondmussel. Description Shell elongate, thin to relatively solid, and moder¬ ately inflated. Anterior end rounded, posterior end pointed (males) or truncated (females). Umbos even with or only slightly elevated above the hinge line. Beak sculpture of five or six strong angular ridges. Periostracum greenish brown to black with clothlike texture. Length to 2.5 inches (6.4 cm). Pseudocardinal teeth relatively thin and compressed, elevated and serrated; two in the left valve, one in the right. Lateral teeth long, straight or curved; two in the left valve, one in the right. Beak cavity shallow. Nacre white, occasionally tinged with salmon in the beak cavity and center of the shell. Habitat Small to medium streams or sloughs in mud or sand in slow-flowing water. Status Essentially a southern species that is rare in the Midwest. Subfamily Lampsilinae 135 Toxolasma texasensis, UIMNH Z- 151 15. Wabash River, White County, Illinois. Length: 2.2 inches (5.6 cm) for male (top), 1.8 inches (4.6 cm) for female (bottom). 136 Mussels of the Midwest Black sandshell Ligumia recta (Lamarck, 1819) Other common names Black sand mussel, long John, honest John, sow’s ear, lady’s slipper. Key characters Elongate shell, pointed on the posterior end, smooth surface, usually dark brown to black, with a pinkish or purple nacre. Similar species Spike, spectaclecase, yellow sandshell. Description Shell elongate, solid, and moderately compressed. Anterior end rounded, posterior end pointed in males, saber¬ shaped in females. Dorsal margin straight, ventral margin straight to curved. Umbos low, only slightly elevated above the hinge line. Beak sculpture, if visible, of two or three indistinct, double- looped bars. Shell smooth and shiny, dark green, brown, or black, with green rays visible on some individuals. Length to 8 inches (20.3 cm). Pseudocardinal teeth triangular, serrated, and divergent; two in the left valve, one in the right, occasionally with a small tooth anteriorly. Lateral teeth long, moderately thin, and straight. Beak cavity shallow. Nacre variable from white, pink, and salmon to deep purple, iridescent posteriorly. Habitat Medium to large rivers in riffles or raceways in gravel or firm sand. Status Widely distributed but uncommon in much of the Midwest. Threatened in Ohio. Subfamily Lampsilinae 137 Ligumia recta , INHS 1 1769 and 11722. Mississippi River, Rock Island County, Illinois. Length: 4.6 inches (1 1.7 cm) for male (top), 4.8 inches (12.2 cm) for female (bottom). 138 Mussels of the Midwest Pondmussel Ligumia subrostrata (Say, 1831) Other common names Western pondmussel, common pondmussel, western sand shell. Key characters Small, elongate shell, pointed or truncated on the posterior end, with thin teeth, beak with numerous wavy ridges if not entirely eroded, yellowish brown with green rays. Similar species Black sandshell, little spectaclecase, Texas lilliput, pondhom. Description Shell relatively small, thin, elongate, and com¬ pressed. Anterior end rounded, posterior end pointed in males, saber-shaped in females. Dorsal and ventral margins straight. Umbos slightly elevated above the hinge line. Beak sculpture of six to eight distinct, wavy ridges but often eroded and not visible. Shell smooth, dull, greenish yellow, becoming darker brown to black in older shells. Dark green rays present but faint in some specimens. Length to 3 inches (7.6 cm). Pseudocardinal teeth thin, compressed, and divergent; two in the left valve, one in the right. Lateral teeth long, thin, and straight; two in the left valve, one in the right. Beak cavity relatively shallow. Nacre white and highly iridescent posteriorly. Habitat Small creeks or ponds in mud or sand. Status May be common in its preferred habitat. Extirpated from Ohio. Subfamily Lampsilinae 139 Ligumia subrostrata, INHS 5569. Skillet Fork, Marion County, Illinois. Length: 2.9 inches (7.4 cm) for male (top), 2.5 inches (6.4 cm) for female (bottom). 140 Mussels of the Midwest Ellipse V enustaconcha ellipsiformis (Conrad, 1836) Other common names None. Key characters Small, elongate shell, relatively thick for its size, with short, heavy lateral teeth and numerous wavy green rays on the posterior half of the shell. Similar species Rayed bean, rainbow, mucket, spike. Description Shell small, solid, elliptical, and compressed. Anterior end rounded, posterior end bluntly pointed. Ventral margin straight to slightly curved. Umbos only slightly elevated above the hinge line. Beak sculpture of three or four very fine, double-looped ridges. Shell usually smooth, with a few wrinkles or folds on the posterior half in older shells. Periostracum green or greenish yellow with numerous dark green rays, becoming wavy on the posterior half of the shell. Length to 3 inches (7.6 cm). Pseudocardinal teeth triangular, heavy, roughened, and divergent; two in the left valve, one in the right (occasionally with a thin, ridgelike tooth in front). Lateral teeth relatively short, thick, and straight to slightly curved. Beak cavity shallow. Nacre white, iridescent posteriorly. Habitat Small to medium streams in gravel or mixed sand and gravel. Status Uncommon. Extirpated from Ohio. Threatened in Iowa and Wisconsin. Species of Special Concern in Illinois and Indiana. Subfamily Lampsilinae 141 Venustaconcha ellipsiformis, INHS 4137. Rock River, Illinois. Length: 2.9 inches (7.4 cm). 142 Mussels of the Midwest Rayed bean Villosa fabalis (Lea, 1831) Other common name Bean shell. Key characters Very small and solid shell with numerous wavy green lines on the outer surface and teeth that are unusually heavy and thick for their size. Similar species Ellipse, rainbow. Description Shell small (usually under 1 inch [2.5 cm]), elongate, thick, solid, and moderately inflated. Anterior end rounded, posterior end rounded to bluntly pointed. Dorsal margin straight, ventral margin straight to slightly curved. Umbos slightly elevated above the hinge line. Beak sculpture, if visible, of two or three heavy ridges. Periostracum green, yellowish green, or brown with numerous wavy green rays. Length to 1.5 inches (3.8 cm). Pseudocardinal teeth triangular, relatively heavy and large; two in the left valve, one in the right. Lateral teeth short, heavy; two in the left valve, one in the right. Beak cavity shallow. Nacre white or bluish white, iridescent posteriorly. Habitat Lakes and small to large streams in sand or gravel. Status Lederal Candidate (Category 2). Endangered in Illinois, Michigan, and Ohio. Species of Special Concern in Indiana. Subfamily Lampsilinae 143 Villosa fabalis, INHS 4885. Salt Fork Vermilion River, Champaign County, Illinois. Length: 1.1 inches (2.8 cm) for male (top), 1.0 inch (2.5 cm) for female (bottom). 144 Mussels of the Midwest Rainbow Villosa iris (Lea, 1829) Other common name Rainbow shell. Key characters Small, relatively thin, and elongate shell, distinct double-looped beak sculpture, yellow, with numerous broken green rays. Similar species Ellipse, rayed bean, fatmucket, mucket. Description Shell small, elongate, relatively thin, and com¬ pressed (males) to moderately inflated (females). Anterior end rounded, posterior end rounded (females) to bluntly pointed (males). Umbos even with or slightly elevated above hinge line. Beak sculpture of four to six distinct, double-looped bars. Periostracum yellow or greenish yellow, with dark green rays, often interrupted. Length to 3 inches (7.6 cm). Pseudocardinal teeth small, triangular, and somewhat divergent; two in the left valve, one in the right. Lateral teeth long, thin, and straight to slightly curved. Beak cavity shallow. Nacre silvery white and highly iridescent on the posterior half, giving this species its common name. Habitat Small to medium streams in coarse sand or gravel. Status Widespread but disappearing from the western part of its range. Endangered in Illinois and Wisconsin. Subfamily Lampsilinae 145 Villosa iris , UIMNH Z- 14080. Tippecanoe River, White County, Indiana. Length: 2.0 inches (5.1 cm) for male (top), 1.9 inches (4.8 cm) for female (bottom). 146 Mussels of the Midwest Little spectaclecase Villosa lienosa (Conrad, 1834) Other common name Black creek shell. Key characters Small shell, dark brown with green rays (often obscure), somewhat elongate, with distinct double-looped beak sculpture and pointed or truncated posterior end. Similar species Pondmussel, pondhom, Texas lilliput. Description Shell small, slightly elongate, thin to moderately thick, compressed in males and inflated in females. Anterior end rounded, posterior end bluntly pointed (males) or truncated (females). Dorsal margin straight, ventral margin straight to slightly curved. Umbos elevated above the hinge line. Beak sculpture of four to seven distinct, double-looped bars. Perio- stracum green to dark brown, with green rays (often obscure). Length to 2.5 inches (6.4 cm). Pseudocardinal teeth relatively small and compressed; two in the left valve, one in the right, with a smaller tooth present anteriorly in some shells. Lateral teeth elongate, thin, and straight. Nacre white or bluish white, occasionally tinged with salmon, iridescent posteriorly. Habitat Small to medium streams in sand or gravel. Status Widespread but uncommon in the Ohio River drainage. Endangered in Illinois and Ohio. Species of Special Concern in Indiana. Subfamily Lampsilinae 147 Villosa lienosa , INHS 4844. North Fork Vermilion River, Vermilion County, Illinois. Length: 1.8 inches (4.6 cm) for both male (top) and female (bottom). 148 Mussels of the Midwest Yellow sandshell Lampsilis teres (Rafinesque, 1820) Other common names Banana shell, bank climber, slough sandshell, creeper, sand clam, luster shell. Key characters Elongate, relatively thick, often glossy shell; adults usually solid yellow, juveniles yellowish green with fine green rays. Similar species Fat mucket, black sandshell, pondhom, scaleshell. Description Shell relatively large, elongate, moderately thick, and somewhat inflated. Anterior end rounded, posterior end pointed in males, truncated in females. Dorsal margin straight, ventral margin straight or occasionally pinched in the middle. Umbos only slightly elevated above the hinge line. Beak sculp¬ ture of four to six double-looped ridges. Shell smooth, very shiny when young, becoming dull with age. Periostracum yellow, usually with green rays in young shells, rayless in older individu¬ als. Length to 6 inches (15.2 cm). Pseudocardinal teeth elongate and compressed; two in the left valve, one in the right (occasionally with a thin, ridgelike tooth in front). Lateral teeth long and straight to slightly curved; two in the left valve, one in the right. Beak cavity moderately deep. Nacre silvery white, occasionally tinged with cream or salmon near the beak cavity, iridescent posteriorly. Habitat Medium to large rivers in sand or fine gravel. Status Endangered in Iowa, Ohio, and Wisconsin. Subfamily Lampsilinae 149 Lampsilis teres, INHS 7386. Embarras River, Lawrence County, Illinois. Length: 4.5 inches (1 1.4 cm) for male (top), 4.4 inches (1 1.2 cm) for female (bottom). 150 Mussels of the Midwest Fatmucket Lampsilis siliquoidea (Bames, 1823) Other common names Grass mucket, black mucket, pugnose mucket. Key characters Elongate, moderately large, and thick shell, yellow or tan with green rays; males bluntly pointed and com¬ pressed, females truncated and inflated. Similar species Yellow sandshell, mucket, plain pocketbook, rainbow, ellipse, pondmussel. Description Shell elongate or elliptical, thin to thick, and compressed (young individuals) to inflated. Anterior end rounded, posterior end bluntly pointed (males) or truncated (females). Dorsal and ventral margins usually straight. Umbos only slightly elevated above the hinge line. Beak sculpture of six to ten double-looped bars. Shell smooth, yellow or yellowish green, sometimes tan or brown, with green rays of various widths that may become indistinct in older individuals. Length to 5 inches (12.7 cm). Pseudocardinal teeth divergent, elongated, or triangular, thin to moderately thick; two in the left valve, one in the right (occasionally with a thin, ridgelike tooth in front). Lateral teeth straight to slightly curved, moderately long, and thin. Beak cavity moderately deep. Nacre white or bluish white and iridescent posteriorly. Habitat Lakes and small to medium-sized streams in mud, sand, or gravel. Status Widespread and common throughout the Midwest. Subfamily Lampsilinae 151 Lampsilis siliquoidea , INHS 3259. Sangamon River, Piatt County, Illinois. Length: 3.6 inches (9.1 cm) for male (top), 3.4 inches (8.6 cm) for female (bottom). 152 Mussels of the Midwest Higgins eye Lampsilis higginsi (Lea, 1857) Other common names None. Key characters Rounded to slightly elongate, thick, smooth, and inflated shell, yellowish brown, with green rays; posterior end bluntly pointed in males, truncated in females. Similar species Pink mucket, mucket, fatmucket, plain pocket- book, hickorynut. Description Shell rounded to slightly elongate, solid, and inflated. Anterior end rounded, posterior end bluntly pointed (males) or truncated (females). Dorsal margin straight, ventral margin straight to slightly curved. Umbos turned forward and elevated above the hinge line. Beak sculpture, if visible, of three or four double-looped ridges. Shell smooth, yellow, yellowish green, or brown with green rays, obscure on some individuals. Length to 4 inches (10.2 cm). Pseudocardinal teeth triangular, thick, divergent; two in the left valve, one in the right, occasionally with a smaller tubercular tooth in front. Lateral teeth fairly long, moderately heavy, and straight. Beak cavity deep. Nacre white, often tinged with cream or salmon near the beak cavity, iridescent posteriorly. Habitat Mississippi River and some of its larger northern tributaries in gravel or sand. Status Federally Endangered. Subfamily Lampsilinae 153 Lampsilis higginsi, INHS 4602 and 1 1767. Mississippi River, Rock Island County, Illinois. Length: 3.5 inches (8.9 cm) for male (top), 3.0 inches (7.6 cm) for female (bottom). 154 Mussels of the Midwest Pink mucket Lampsilis abrupta (Say, 1831) Other common names Ohio mucket, tan mucket, square mucket. Key characters A rounded to slightly elongate shell, thick, inflated, smooth, and yellowish brown; posterior end bluntly pointed in males, truncated in females. Similar species Higgins eye, mucket, fatmucket, plain pocket- book, hickorynut. Description Shell round to elliptical, solid, and inflated. Anterior end rounded, posterior end bluntly pointed in males, truncated in females. Dorsal margin straight, ventral margin straight to slightly curved. Umbos turned forward and elevated above the hinge line. Beak sculpture, if visible, of three or four double-looped ridges. Shell smooth, yellow or yellowish green and rayless or with faint green rays. Length to 4 inches (10.2 cm). Pseudocardinal teeth triangular, thick, divergent; two in the left valve, one in the right, occasionally with a smaller tubercular tooth in front. Lateral teeth short, heavy, and relatively thick. Beak cavity deep. Nacre pink or white, iridescent posteriorly. Habitat The lower Mississippi and Ohio rivers and their larger tributaries in gravel or sand. Status Federally Endangered. Subfamily Lampsilinae 155 Lampsilis abrupta , INHS 13809. Tennessee River, Hardin County, Tennessee. Length: 3.6 inches (9.1 cm) for male (top), 2.9 inches (7.4 cm) for female (bottom). 156 Mussels of the Midwest Plain pocketbook Lampsilis cardium Rafinesque, 1820 Other common names Grandmaw, pocketbook. Key characters Moderately thin, inflated, round to somewhat squarish shell with the posterior end bluntly pointed in males and truncated in females; smooth outer surface, yellow or tan with or without green rays. Similar species Fat pocketbook, pocketbook, mucket, pink mucket, Higgins eye. Description Shell large, round or somewhat quadrate, thin to moderately thick (particularly in older individuals), and inflated. Anterior end rounded, posterior end bluntly pointed (males) to truncated (females). Dorsal and ventral margins straight to curved. Umbos turned forward and elevated above the hinge line. Beak sculpture of four or five elevated ridges. Periostracum smooth, yellow or yellowish green, usually with numerous dark green rays of various widths. Length to 7 inches (17.8 cm). Pseudocardinal teeth relatively large, elevated, and rough¬ ened in young individuals, smoother in old specimens; two in the left valve, one in the right. Lateral teeth straight to curved, moderate in length, and striated. Beak cavity deep. Nacre white or bluish white, occasionally pink or salmon, iridescent posteri¬ orly. Habitat Small creeks to large rivers in mud, sand, or gravel. Status Widespread and common throughout its range. Subfamily Lampsilinae 157 Lampsilis cardium , INHS 8898. East Fork Spoon River, Stark County, Illinois. Length: 4.0 inches (10.2 cm) for male (top), 3.5 inches (8.9 cm) for female (bottom). 158 Mussels of the Midwest Pocketbook Lampsilis ovata (Say, 1817) Other common names Sharp-ridged pocketbook, southern pocketbook, grandmaw. Key characters A round or oblong shell, inflated, posterior end bluntly pointed in males and truncated in females; prominent, sharply angled posterior ridge; outer surface smooth, yellow or tan, and usually rayless except on the posterior slope. Similar species Plain pocketbook, mucket, fat pocketbook, pink mucket. Description Similar in shape to the plain pocketbook. Shell relatively large, rounded or oval, thin to moderately thick, and inflated. Anterior end rounded, posterior end bluntly pointed in males, truncated in females. Dorsal margin straight, ventral margin curved. Umbos elevated above the hinge line. Prominent, sharply angled posterior ridge present. Shell smooth, yellow or yellowish brown, darker on the posterior slope, with rays largely absent in adults except for a few thin green lines on the umbos and posterior slope. Length to 6 inches (15.2 cm). Pseudocardinal teeth thick, compressed and elevated; two in the left valve, one in the right. Lateral teeth curved and short. Beak cavity large and deep. Nacre white, iridescent posteriorly. Habitat Large rivers in coarse sand or gravel. Status Rare in the Ohio River and some of its larger tributaries. Endangered in Ohio. Likely extirpated from Illinois. Subfamily Lampsilinae 159 Lampsilis ovata, INHS 1076 (Ohio River, Alexander County, Illinois) and UIMNH Z-4021 (Duck River, Maury County, Tennessee). Length: 4.2 inches (10.7 cm) for male (top), 3.8 inches (9.7 cm) for female (bottom). 160 Mussels of the Midwest Wavy-rayed lampmussel Lamp silis fasciola Rafinesque, 1820 Other common name Wavy-lined lampmussel. Key characters A rounded shell, moderately thick in adults, yellow or yellowish green, with numerous thin wavy green rays. Similar species Plain pocketbook, pocketbook. Description Shell moderately thick, round or ovate, compressed to inflated. Anterior end rounded, posterior end bluntly pointed in males, truncated in females. Dorsal margin straight, ventral margin curved. Umbos only slightly elevated above the hinge line. Beak sculpture of three to five indistinct wavy ridges. Shell smooth, yellow or yellowish green, with numerous thin, wavy green rays. Length to 3.5 inches (8.9 cm). Pseudocardinal teeth triangular, short, thick, and divergent; two in the left valve, one in the right, occasionally with a smaller tooth on either side. Lateral teeth short and straight or slightly curved. Beak cavity moderately deep. Nacre white, iridescent posteriorly. Habitat Medium-sized streams in gravel riffles. Status Widely distributed but uncommon in northern tributaries of the Ohio River. Endangered in Illinois. Species of Special Concern in Indiana and Michigan. Species of Special Interest in Ohio. Subfamily Lampsilinae 161 Lampsilis fasciola, INHS 8616. Salt Fork Vermilion River, Vermilion County, Illinois. Length: 3.0 inches (7.6 cm) for male (top), 2.8 inches (7.1 cm) for female (bottom). 162 Mussels of the Midwest Snuffbox Epioblasma triquetra (Rafinesque, 1 820) Other common names None. Key characters A triangular shell, relatively thick for its size with a sharply defined, broadly expanded posterior slope. Yellow or yellowish green with green rays, blotches, or chevron markings. Similar species Elktoe, deertoe, fawnsfoot. Description Shell small, fairly solid, triangular (males) to somewhat elongate (females) and inflated (particularly in females). Anterior end rounded, posterior end truncated in males, expanded in females. Dorsal and ventral margins straight to slightly curved. Posterior ridge sharply angled, posterior slope wide, expanded, and ribbed (especially in females). Umbos swollen and slightly elevated above the hinge line. Beak sculp¬ ture of three or four faint, double-looped bars. Periostracum yellow or yellowish green, with numerous dark green rays, blotches or chevron-shaped markings. Length to 2.5 inches (6.4 cm). Pseudocardinal teeth elevated, roughened, relatively thin and compressed; two in the left valve, two in the right, with the front one being thinner and much smaller. Lateral teeth very short, slightly curved, serrated, and elevated. Beak cavity fairly deep. Nacre pearly white, iridescent posteriorly. Habitat Medium to large rivers in clear, gravel riffles. Status Widespread but rare throughout the Midwest. Federal Candidate (Category 2). Endangered in Illinois, Indiana, Wiscon¬ sin, and Michigan. Threatened in Ohio. Rare in Missouri. Subfamily Lampsilinae 163 Epioblasma triquetra, INHS 5808. Embarras River, Douglas County, Illinois. Length: 2.4 inches (6.1 cm) for male (top), 1.9 inches (4.8 cm) for female (bottom). 164 Mussels of the Midwest Catspaw Epioblasma obliquata (Rafinesque, 1820) Other common names Peewee. Key characters Males and females both yellowish brown or brown but much different in shape. Males oblong and solid, with a shallow sulcus along the posterior ridge from the umbo to the ventral margin. Females rectangular, truncated, and inflated pos¬ teriorly with a finely grooved surface and serrated growth lines. Similar species Northern riffleshell. Description Shell small, solid, rectangular or quadrate in fe¬ males, oval and elongate in males, and moderately inflated. Ante¬ rior margin rounded, posterior margin bluntly pointed in males, expanded, truncated, ribbed, and notched in females. Ventral margin broadly curved in males, straight to slightly curved in females. Umbos full, about even with the hinge line and directed forward. Posterior ridge double, with a relatively wide sulcus or depression between the ridges in males, depression sharp and narrow in females. Posterior-ventral portion of the shell in fe¬ males inflated with fine grooves that radiate from the umbo to the margin of the shell. Growth lines serrated on the edge in the pos¬ terior third of the shell in the female. Periostracum yellowish tan or brown, with numerous fine green rays most evident in females. Length to 2 inches (5.1 cm). Males much larger than females. Pseudocardinal teeth wide, elevated, serrated, horizontal; two in left valve, one in right with two smaller teeth on either side. Lateral teeth short, straight to slightly curved, roughened; two in left valve, one in right with a much smaller tooth below. Beak cavity shallow. Nacre white to purple, iridescent posteriorly. Habitat Medium to large rivers in gravel riffles. Status Federally Endangered. Subfamily Lampsilinae 165 Epioblasma obliquata, UIMNH Z-3767. Tennessee River, Lauderdale County, Alabama. Length: 1.8 inches (4.6 cm) for male (top), 1.2 inches (3.0 cm) for female (bottom). 166 Mussels of the Midwest Tubercled blossom Epioblasma torulosa (Rafinesque, 1820) Other common names None. Key characters Males and females yellowish brown with green rays but much different in shape. Males oblong with a sulcus running along the posterior ridge from the umbo to the ventral margin. Females with a large expanded posterior end. Both with a series of enlarged knobs running from the beaks and continuing to the posterior-ventral margin. Similar species Northern riffleshell, sheepnose, threehorn wartyback. Description Shell thick anteriorly, much thinner posteriorly, • elongate, and inflated. Anterior margin rounded, posterior-ventral margin broadly rounded or slightly truncated in females, indented in males. Umbos low, somewhat turned forward. Beak sculpture of two or three indistinct ridges, evident only in very young shells. A row of large tubercles or knobs running from the beaks and continuing to the posterior-ventral margin. A wide, shallow sulcus or depression present between the row of knobs and the posterior ridge. Periostracum yellowish brown with numerous fine green rays, obscure in older shells. Length to 3 inches (7.6 cm). Pseudocardinal teeth triangular, divergent, and roughened; two in the left valve, one in the right with two smaller teeth on either side. Lateral teeth short, straight and roughened; two in the left valve, one in the right with a much smaller tooth below. Beak cavity moderate to shallow. Nacre white, iridescent posteriorly. Habitat Medium to large rivers in gravel riffles. Status Federally Endangered. Extirpated from the Midwest. Subfamily Lampsilinae 167 Epioblasma torulosa , UIMNH Z-3947. Tennessee River, Lauderdale County, Alabama. Length: 2.2 inches (5.6 cm) for male (top), 2.1 inches (5.3 cm) for female (bottom). 168 Mussels of the Midwest Northern riffleshell Epioblasma rangiana (Lea, 1839) Other common name White-mouth riffleshell. Key characters Males and females yellowish brown or green but much different in shape. Males oblong with a sulcus running along the posterior ridge from the umbo to the ventral margin. Females with a large expanded posterior end. Tubercles on the lateral surface greatly reduced or absent. Similar species Tubercled blossom. Description Shell elongate, thick anteriorly, much thinner posteriorly, and compressed. Anterior margin rounded, posterior- ventral margin broadly rounded in females, indented in males. Umbos low, somewhat turned forward. Tubercles or knobs on the lateral surface greatly reduced or absent. A wide, shallow sulcus or depression present between the posterior and medial ridges. Periostracum yellowish brown with numerous fine green rays, obscure in older shells. Length to 2 inches (5.1 cm). Pseudocardinal teeth triangular, divergent, and roughened; two in the left valve, one in the right, with two smaller teeth on either side. Lateral teeth moderately long, straight, and rough¬ ened; two in the left valve, one in the right with a much smaller tooth below. Beak cavity moderate to shallow. Nacre white, iridescent posteriorly. Habitat Medium to large rivers in gravel riffles. Status Proposed for Federal Endangered status. Endangered in Indiana, Michigan, and Ohio. Extirpated from Illinois. Subfamily Lampsilinae 169 Epioblasma rangiana , INHS 1675. White River, Indiana. Length: 1.8 inches (4.6 cm) for both male (top) and female (bottom). 170 Mussels of the Midwest Extinct species Leafshell Epioblasma flexuosa (Rafinesque, 1820) Round combshell Epioblasma personata (Say, 1829) Tennessee riffleshell Epioblasma propinqua (Lea, 1857) Wabash riffleshell Epioblasma sampsonii (Lea, 1861) The four species of the genus Epioblasma listed above have not been found alive in the Midwest in more than 75 years, and all are currently considered extinct (Turgeon et al. 1988, Appendix 2). Three are illustrated here in the likelihood their shells may be encountered while collecting along the banks of the Wabash and Ohio rivers and their larger tributaries. Subfamily Lampsilinae 171 From top to bottom: Epioblasma flexuosa, INHS 1747. Length: 2.6 inches (6.6 cm). Epioblasma personata , INHS 1468. Ohio River. Length: 1.9 inches (4.8 cm). Epioblasma propinqua, INHS 3206. Length: 2.2 inches (5.6 cm). 172 Mussels of the Midwest Fingernailclams and Peaclams (Family Sphaeriidae) Musculium, Pisidium, and Sphaerium Other common names Pillclams, nutclams. Key characters Small, whitish or cream-colored shell with numerous, very fine concentric rows of elevated lines (striae) covering the surface. The right valve has one cardinal tooth and two pairs of lateral teeth. The left valve has two cardinal teeth and two lateral teeth. Similar species Asian clam. Description Shell rounded to slightly oval and inflated. Anterior and posterior margins rounded. Umbos centrally located and slightly elevated above the hinge line. Periostracum whitish or cream-colored, with numerous, very fine concentric rows of elevated lines (striae) covering the surface of the shell. The posterior end of the shell is longer in Sphaerium and Musculium , and just the reverse in Pisidium. Length to 0.5 inch (1.3 cm). The right valve has one cardinal tooth and two pairs of lateral teeth. The left valve has two cardinal teeth and two lateral teeth. Beak cavity moderately deep. Nacre white. Habitat Lakes and streams of all sizes in silt, mud, sand, or gravel. Status Little is known regarding the status of fingernailclams and peaclams. They have disappeared from many streams where they were formerly abundant (such as the Illinois River). Family Sphaeriidae 173 Sphaeriidae, INHS 14999. Kishwaukee River, McHenry County, Illinois. Length: 0.5 inch (1.3 cm). 174 Mussels of the Midwest Asian clam Corbicula fluminea (Muller, 1774) Other common names Asiatic clam, Corbicula. Key characters Relatively small, yellowish brown to black shell with numerous, evenly spaced, concentric, elevated ridges on the surface. Three cardinal teeth in each valve located below the umbo. Paired lateral teeth in each valve, two on each side of the umbo in the right valve, one on each side in the left. The presence of serrated lateral teeth separate Corbicula from the fingernail- clams. Similar species Fingemailclam. Description Shell rounded to slightly triangular and inflated. Anterior and posterior margins rounded. Umbos high, centrally located, and elevated above the hinge line. Periostracum yellow¬ ish brown to black with numerous concentric rows of elevated lines covering the surface of the shell. Young shells with a purple stripe on the umbo. Length to 1.5 inches (3.8 cm). Three triangular cardinal teeth in each valve located directly below the umbo. Two sets of lateral teeth in each valve, moder¬ ately long, straight, and serrated; paired in the right valve, one on each side in the left. Beak cavity deep. Nacre white or purple and highly polished outside of the pallial line. Habitat Lakes and streams of all sizes in silt, mud, sand, or gravel. Status Widespread and common. Introduced. Family Corbiculidae 175 Corbicula fluminea, INHS 7276. South Fork Sangamon River, Christian County, Illinois. Length: 1.5 inches (3.8 cm). 176 Mussels of the Midwest Zebra mussel Dreissena polymorpha (Pallas, 1771) Other common names None. Key characters Relatively small, triangular, and elongate shells with alternating cream and brown bands on the surface. Similar species Dark falsemussel. See Marsden (1992) for information on distinguishing between these two species. Description Adults with a distinctively shaped, elongate, triangular, and inflated shell. Highly variable with respect to color as its scientific name polymorpha (many forms) indicates. Most are white or cream-colored with jagged lateral brown to black stripes or bands, which give the species its common name. Some have longitudinal bands, and all-cream or all-black individuals have been found. Length to 1.5 inches (3.8 cm). No pseudocardinal or lateral teeth. A small shelf or septum present at the anterior end forming a moderately deep beak cavity. Nacre white and somewhat polished. Habitat Lakes and streams of all sizes; attaches to rocks, freshwater mussels, or almost any hard surface by gluelike fibers called byssal threads. Status Introduced into the Great Lakes from eastern Europe and rapidly spreading throughout the United States. Family Dreissenidae Dreissena polymorpha attached to Potamilus alatus , INHS 13808. Lake Erie, Ottawa County, Ohio. Length: 0.8 inch (2.0 cm). IlMlIW Literature Cited Baker, F.C. 1930. The use of animal life by the mound-building Indians of Illinois. Transactions of the Illinois State Academy of Science 22:41- 59 + 6 plates. Burch, J.B. 1975. Freshwater Unionacean clams (Mollusca: Pelecypoda) of North America. Malacological Publications, xviii + 204 pp. Coker, R.E. 1919. Fresh-water mussels and mussel industries of the United States. Bulletin of the U.S. Bureau of Fisheries 36. 89 pp. Cummings, K.S., and J.M.K. Berlocher. 1990. The naiades or freshwater mussels (Bivalvia: Unionidae) of the Tippecanoe River, Indiana. Malacological Review 23( 1— 2):83— 98. Hoeh, W.R. 1990. Phylogenetic relationships among eastern North American Anodonta (Bivalvia: Unionidae). Malacological Review 23(l-2):63-82. Marsden, J.E. 1992. Standard protocols for monitoring and sampling zebra mussels. Illinois Natural History Survey Biological Notes 138. 40 pp. Matteson, M.R. 1953. Fresh-water mussels used by Illinoisan Indians of the Hopewell culture. Nautilus 66(4): 130-1 38, 67(l):25-26. Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of Missouri. Missouri Department of Conservation, Jefferson City, Missouri, vii + 270 pp. Parmalee, P.W. 1967. The fresh-water mussels of Illinois. Illinois State Museum, Popular Science Series 8. 108 pp. Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, W.G. Lyons, W.L. Pratt, C.F.E. Roper, A. Scheltema, F.G. Thompson, and J.D. Williams. 1988. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. American Fisheries Society Special Publication 16. 277 pp. 180 Mussels of the Midwest U.S. Fish and Wildlife Service (USFWS). 1990a. White cat’s paw pearly mussel recovery plan. U.S. Fish & Wildlife Service, Twin Cities, Minnesota. 42 pp. - 1990b. Endangered and threatened wildlife and plants; review of plant taxa for listing as endangered or threatened species; notice of review. Federal Register 55(35):6185. - 1991a. Threatened and endangered wildlife and plants 50 CFR 17.11 & 17.12. July 15, 1991.37 pp. - 1991b. Endangered and threatened wildlife and plants; 5-year review of listed species; proposed rule. Federal Register 56(215): 56883. - 1991c. Endangered and threatened wildlife and plants; animal candidate review for listing as endangered or threatened species, proposed rule. Federal Register 56(225):58804-58836. van der Schalie, H. 1941. Fresh water mussels. Pages 61-67 in J.K. Jacobson, ed. How to study and collect shells (a symposium). The American Malacological Union, 1974. 107 pp. Additional Reading Illinois Baker, F.C. 1898. The Mollusca of the Chicago area, Part I: The Pelecypoda. Bulletin of the Chicago Academy of Sciences 3(1): 1-130 + 27 plates. - 1906. A catalogue of the Mollusca of Illinois. Bulletin of the Illinois State Laboratory of Natural History 7(6):53-136 + 1 map. - 1922. The molluscan fauna of the Big Vermilion River, Illinois. With special reference to its modification as the result of pollution by sewage and manufacturing wastes. Illinois Biological Monographs 7(2): 105-224 + 15 plates. - 1926. The naiad fauna of the Rock River system: A study of the law of stream distribution. Transactions of the Illinois State Academy of Science 19:103-112. Cummings, K.S. 1991. The Aquatic Mollusca of Illinois. Pages 429-439 in L.M. Page and M.R. Jeffords, eds. Our Living Heritage: The Biologi¬ cal Resources of Illinois. Illinois Natural History Survey Bulletin 34(4):357-477. Parmalee, P.W. 1967. The fresh-water mussels of Illinois. Illinois State Museum Popular Science Series 8. 108 pp. Schanzle, R.W., and K.S. Cummings. 1991. A survey of the freshwater mussels (Bivalvia: Unionidae) of the Sangamon River basin, Illinois. Illinois Natural History Survey Biological Notes 137. 25 pp. Starrett, W.C. 1971. A survey of the mussels (Unionacea) of the Illinois River: a polluted stream. Illinois Natural History Survey Bulletin 30(5):267-403. Strode, W.S. 1892. The Unionidae of Spoon River, Fulton County, Illinois. American Naturalist 26:495-501. Suloway, L. 1981. The unionid (Mollusca: Bivalvia) fauna of the Kan¬ kakee River in Illinois. American Midland Naturalist 105(2):233-239. 182 M ussels of the Midwest Suloway, L., J.J. Suloway, and E.E. Herricks. 1981. Changes in the freshwater mussel (Mollusca: Pelecypoda: Unionidae) fauna of the Kaskaskia River, Illinois, with emphasis on the effects of impoundment. Transactions of the Illinois State Academy of Science 74(l/2):79-90. Wilson, C.B., and H.W. Clark. 1912. The mussel fauna of the Kankakee basin. Report and Special Papers of the U.S. Fish Commis¬ sion, 1911. 52 pp. -t- 1 map. [Issued separately as U.S. Bureau of Fisheries Document 758], Indiana Call, R.E. 1900. A descriptive illustrated catalogue of the Mollusca of Indiana. 24th Annual Report of the Indiana Department of Geology and Natural Resources, 1899. 200 pp. + 78 plates. Cummings, K.S., and J.M.K. Berlocher. 1990. The naiades or freshwater mussels (Bivalvia: Unionidae) of the Tippecanoe River, Indiana. Malacological Review 23( 1— 2):83— 98. Daniels, L.E. 1903. A check list of Indiana Mollusca, with localities. 26th Annual Report of the Indiana Geological Survey, 1902. 23 pp. Goodrich, C., and H. van der Schalie. 1944. A revision of the Mollusca of Indiana. American Midland Naturalist 32(2):257-326. Harmon, J.L. 1989. Freshwater bivalve mollusks (Bivalvia: Unionidae) of Graham Creek, a small southeastern Indiana stream. Malacology Data Net 2(5-6): 113-121. - 1992. Naiades (Bivalvia: Unionidae) of Sugar Creek, East Fork White River Drainage, in central Indiana. Malacology Data Net 3(1^1): 31-42. Krumholz, L.A., R.E. Bingham, and E.R. Meyer. 1970. A survey of the commercially valuable mussels of the Wabash and White Rivers of Indiana. Proceedings of the Indiana Academy of Science 79:205-226. Meyer, E.R. 1974. Unionid mussels of the Wabash, White, and East Fork White Rivers, Indiana. Virginia Journal of Science 25(l):20-25. Taylor, R.W. 1982. The freshwater mussels (naiads) of Big Indian Creek, a small southern Indiana tributary of the Ohio River (Bivalvia: Unionidae). Nautilus 96(2):66-68. Additional Reading 183 Weilbaker, C., C.D. Baker, B.J. Forsyth, C.M. Christenson, and R.W. Taylor. 1985. The freshwater naiads, Bivalvia: Unionidae, of the Blue River, a Southern Indiana tributary of the Ohio River. Proceedings of the Indiana Academy of Science 94:687-691. Iowa Keyes, C.R. 1888. An annotated catalogue of the Mollusca of Iowa. Bulletin of the Essex Institute 20(4-6) :6 1-83. Shimek, B. 1888. The Mollusca of eastern Iowa. Iowa University Natural History Bulletin 1:56-81. - 1935. The effect of pollution on mollusks in Iowa. Nautilus 48(4): 109-1 11. Witter, F.M. 1878. List of the shells of Iowa. Quarterly Journal of Conchology 1878:385-394. Michigan Boss, K.J. 1964. Unionidae of Red Cedar River, Michigan. Nautilus 77(4): 11 7-1 18. Burch, J.B., and C.M. Paterson. 1976. Key to the genera of freshwater pelecypods (mussels and clams) of Michigan. Museum of Zoology, University of Michigan Circular 4. 35 pp. De Camp, W.H. 1881. List of shell-bearing Mollusca of Michigan. Kent Scientific Institute, Grand Rapids, Michigan. 13 pp. + 1 plate. Goodrich, C. 1932. The Mollusca of Michigan. Michigan Handbook Series No. 5. University of Michigan Press, Ann Arbor, Michigan. 120 pp. + 7 plates. Goodrich, C., and H. van der Schalie. 1932. 1. On an increase in the naiad fauna of Saginaw Bay, Michigan. II. The naiad species of the Great Lakes. Occasional Papers of the Museum of Zoology, University of Michigan No. 238. 14 pp. - 1939. Aquatic mollusks of the Upper Peninsula of Michigan. Miscellaneous Publications 43, Museum of Zoology, University of Michigan. 45 pp. 184 Mussels of the Midwest Hoeh, W.R., and R.J. Trdan. 1984. The freshwater mussels (Pelecypoda: Unionidae) of the Upper Tittabawassee River drainage, Michigan. Malacological Review 1 7( 1— 2):97 — 98. - 1985. Freshwater mussels (Pelecypoda: Unionidae) of the major tributaries of the St. Clair River, Michigan. Malacological Review 1 8(1/2): 1 15-1 16. Strayer, D.L. 1979. Some recent collections of mussels from Southeast¬ ern Michigan. Malacological Review 1 2( 1— 2):93— 95. - 1980. The freshwater mussels (Bivalvia: Unionidae) of the Clinton River, Michigan, with comments on man’s impact on the fauna, 1870-1978. Nautilus 94(4): 142-149. van der Schalie, H. 1936. The naiad fauna of the St. Joseph River drainage in Southwestern Michigan. American Midland Naturalist 17(2):523-527. - 1938. The naiad fauna of the Huron River, in southeastern Michigan. Miscellaneous Publications 40, Museum of Zoology, University of Michigan. 83 pp. - 1948. The commercially valuable mussels of the Grand River in Michigan. Miscellaneous Publication 4, Michigan Department of Conservation. 42 pp. Walker, B. 1879. Catalogue of the shell-bearing Mollusca of Michigan. Journal of Conchology 1879:325-337. - 1892. The shell bearing Mollusca of Michigan. Nautilus 6(2): 13-19, 6(3):3 1—35, 6(4):42^17, 6(6):63-67. - 1893. The shell bearing Mollusca of Michigan (cont.). Nautilus 6:135-141. - (1894-1895). A review of our present knowledge of the molluscan fauna of Michigan. Thomas Smith Press, Detroit, Michigan. 27 pp. [Reprinted in Sterkiana (1965)17:10-25.] - 1898. The distribution of the Unionidae in Michigan. Privately published by Bryant Walker, Detroit, Michigan. 23 pp. Additional Reading 185 Winslow, M.L. 1917. An annotated list of shells from northern Michi¬ gan. Occasional Papers of the Museum of Zoology, University of Michigan No. 42. 16 pp. - 1926. A revised check list of Michigan Mollusca. Occasional Papers of the Museum of Zoology, University of Michigan No. 181. 28 pp. Minnesota Cvancara, A.M. 1970. Mussels (Unionidae) of the Red River valley in North Dakota and Minnesota, U.S.A. Malacologia 10(1 ):57— 92. Dawley, C. 1947. Distribution of aquatic mollusks in Minnesota. American Midland Naturalist 38:671-697. Grant, U.S. 1888. Notes on the molluscan fauna of Minnesota. Geology and Natural History Survey of Minnesota 16:481-484. Wilson, C.B., and E. Danglade. 1914. The mussel fauna of central and northern Minnesota. Report of the U.S. Commissioner of Fisheries for 1913. Appendix 5:1-6. [Issued separately as U.S. Bureau of Fisheries Document 803]. Missouri Buchanan, A.C. 1980. Mussels (Naiades) of the Meramec River Basin, Missouri. Aquatic Series 17, Missouri Department of Conservation. 68 pp. Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of Missouri. Missouri Department of Conservation. Jefferson City, Missouri, vii + 270 pp. Utterback, W.I. 1915. The naiades of Missouri. American Midland Naturalist 4:41-53,69-152, 189-204,244-273. - 1916. The naiades of Missouri. American Midland Naturalist 4:31 1-327, 339-354, 387^100, 432-464. Utterback, W.I., and E.M. Campbell. 1914. Mussel resources in Missouri. Department of Commerce, Bureau of Fisheries Circular 10. 6 pp. 186 Mussels of the Midwest Warren, R.E. 1991. Ozarkian fresh-water mussels (Unionoidea) in the upper Eleven Point River, Missouri. American Malacological Bulletin 8(2): 131—137. Ohio Anthony, J.G. 1844. Collection of the terrestrial and fluviatile shells of Ohio. Proceedings of the Academy of Natural Sciences of Philadelphia 2( 1 ):6 — 7. Clark, C.F. 1977. The freshwater naiades of Ohio. Part I: St. Joseph River of the Maumee. Sterkiana 65-66:14-36. - 1987. The freshwater naiads of Ohio, Part V, Wabash River drainage of Ohio. Malacology Data Net 2(1-2): 19-37. Clark, H.W., and C.B. Wilson. 1912. The mussel fauna of the Maumee River. Report and Special Papers of the U.S. Fish Commission, 1911. 72 pp. [Issued separately as U.S. Bureau of Fisheries Document 757]. Dean, G.W. 1890. Distribution of Unionidae in the three rivers, Mahoning, Cuyahoga and Tuscarawas. Nautilus 4(2):20-21. Hoggarth, M.A. 1990. The Unionidae of the Chagrin River: The remnant of a molluscan fauna. Ohio Journal of Science 90(5): 168-170. Lewis, J. 1877. Unionidae of Ohio and Alabama. Proceedings of the Academy of Natural Sciences of Philadelphia 29:26-36. Sterki, V. 1907. A preliminary catalogue of the land and fresh-water Mollusca of Ohio. Proceedings of the Ohio State Academy of Science 4(8):367-402. Watters, G.T. 1992. Distribution of the Unionidae in South Central Ohio. Malacology Data Net 3(1^4):56-90. Wisconsin Baker, F.C. 1928. The fresh water Mollusca of Wisconsin. Part II. Pelecypoda. Bulletin of the Wisconsin Geological and Natural History Survey, vol. 70, No. 2. University of Wisconsin, vi + 495 pp. Chadwick, G.H. 1905. List of Wisconsin shells. Nautilus 19(5):57-60. Additional Reading 187 - 1906. List of Wisconsin shells (cont.). Nautilus 20(2):22-24. Flowers, W. 1975. Notes on the current status of Wisconsin Unionidae. Sterkiana 57:40-42. Lapham, I. A. 1852. Catalogue of the Mollusca of Wisconsin. Transac¬ tions of the Wisconsin State Agricultural Society 2:367-370. - 1860. List of the shells of Wisconsin. Proceedings of the Academy of Natural Sciences of Philadelphia 12:154-156. Mathiak, H.A. 1979. A river survey of the unionid mussels of Wiscon¬ sin 1973-1977. Sand Shell Press, Horicon, Wisconsin. 75 pp. Morrison, J.P.E. 1932. A report on the Mollusca of the northeastern Wisconsin lake district. Transactions of the Wisconsin Academy of Sciences, Arts and Letters 27:359-396. Roy, E.C. Jr. 1963. Checklist of Pleistocene and living Mollusca of Wisconsin. Sterkiana 10:5-21. Stern, E.M. 1990. An illustrated key to the freshwater mussels (Bivalvia: Unionidae) of Wisconsin. Reports of the Museum of Natural History No. 20. University of Wisconsin-Stevens Point. 75 pp. Mississippi River Scarpino, P.V. 1985. Great River. An environmental history of the Upper Mississippi, 1890-1950. University of Missouri Press, Columbia, Missouri, viii + 219 pp. van der Schalie, H., and A. van der Schalie. 1950. The mussels of the Mississippi River. American Midland Naturalist 44(2)448-466. Ohio River Rafinesque, C.S. 1820. Monographic des coquilles bivalves fluviatiles de la Riviere Ohio, contenant douze genres et soixante-huit especes. Annales Generates des Sciences Physiques, Bruxelles 5(13):287-322 + 2 plates. Taylor, R.W. 1989. Changes in freshwater mussel populations of the Ohio River: 1,000 BP to recent times. Ohio Journal of Science 89(5): 188-191. 188 Mussels of the Midwest Williams, J.C., and G.A. Schuster. 1989. Freshwater mussel investiga¬ tions of the Ohio River, mile 317.0 to mile 981.0. Kentucky Department of Fish and Wildlife Resources, Division of Fisheries, Frankfort, Kentucky. 57 pp. Use of Mussels by Native Americans Baker, F.C. 1930. The use of animal life by the mound-building Indians of Illinois. Transactions of the Illinois State Academy of Science 22:41- 59 + 6 plates. Matteson, M.R. 1953. Fresh-water mussels used by Illinoisan Indians of the Hopewell culture. Nautilus 66(4): 130-1 38, 67( 1 ):25— 26. - 1958. Analysis of an environment as suggested by shells of fresh-water mussels discarded by Indians of Illinois. Transactions of the Illinois State Academy of Science 5 1 (3 — 4):8— 1 3. - 1959. An analysis of the shells of fresh-water mussels gathered by Indians in southwestern Illinois. Transactions of the Illinois State Academy of Science 52(l-2):52-58. Murray, H.D. 1981. Unionids from Indian sites in McMullen and Live Oak Counties, Texas. Bulletin of the American Malacological Union 1981:10-11. Ortmann, A.E. 1909. Unionidae from an Indian garbage heap. Nautilus 23(1): 1 1—15. Parmalee, P.W., A. A. Paloumpis, and N. Wilson. 1972. Animals utilized by woodland peoples occupying the Apple Creek site, Illinois. Illinois State Museum Reports of Investigations 23. 62 pp. Parmalee, P.W., and A.E. Bogan. 1986. Molluscan remains from aboriginal middens at the Clinch River breeder reactor plant site, Roane County, Tennessee. American Malacological Bulletin 4(l):25-37. Parmalee, P.W., and W.E. Klippel. 1986. A prehistoric aboriginal freshwater mussel assemblage from the Duck River in Middle Tennes¬ see. Nautilus 100(4): 134-140. Parmalee, P.W., W.E. Klippel, and A.E. Bogan. 1982. Aboriginal and modem freshwater mussel assemblages (Pelecypoda: Unionidae) from the Chickamauga Reservoir, Tennessee. Brimleyana 8:75-90. Additional Reading 189 Stansbery, D.H. 1966. Utilization of naiads by prehistoric man in the Ohio Valley. American Malacological Union Incorporated Annual Reports 32:4 1 —43. Taylor, R.W. 1982. Mollusk shells associated with evidence of habitation by prehistoric Native Americans in a Hardin County, Kentucky cave. Transactions of the Kentucky Academy of Science 43(3 — 4): 155—157. Taylor, R.W., and B.D. Spurlock. 1982. The changing Ohio River naiad fauna: A comparison of early Indian middens with today. Nautilus 96(2):49— 51. Theler, J.L. 1991. Aboriginal utilization of freshwater mussels at the Azatlan site, Wisconsin. Pages 315-332 in J.R. Purdue, W.E. Klippel, and B.W. Styles, eds. Beamers, bobwhites, and blue-points. Tributes to the career of Paul W. Parmalee. Illinois State Museum Scientific Papers No. 23 and the University of Tennessee Department of Anthropology Report of Investigations No. 52. ix + 436 pp. Index Actinonaias ligamentina 104 Alasmidonta marginata 84 Alasmidonta viridis 86 Amblema plicata 40 Anodonta grandis 78 Anodonta imbecillis 74 Anodonta suborbiculata 76 Anodontoides ferussacianus 80 Arcidens confragosus 88 Asian clam 174 Asiatic clam 174 Bald-pate 24 Banana shell 148 Bank climber 148 Bastard 88 Bean shell 142 Black creek shell 146 Black mucket 150 Black pocketbook 88 Black sand mussel 136 Black sandshell 136 Bleufer 126 Blooper 126 Blue ham 66 Blue hen 126 Blue mucket 126 Blue-point 40 Board 24 Brass mucket 104 Buckhom 26 Bullhead 50 Bullnose 58 Butterfly 106 Catspaw 164 Chestnut shell 108 Clubshell 56 Common pondmussel 138 Corbicula 174 Corbicula fluminea 174 Cottonmouth 120 Cracking pearlymussel 70 Creek heelsplitter 96 Creeper 82, 148 Cumberlandia monodonta 22 Cyclonaias tuberculata 48 Cylinder 80 Cylindrical papershell 80 Cyprogenia stegaria 1 02 Deerhom 48,114 Deertoe 114 Dreissena polymorpha 176 Eastern fanshell 102 Ebonyshell 42 Eggshell 108 Elephant-ear 66, 92 Elktoe 84 Ellipsaria lineolata 106 Ellipse 140 Elliptio crassidens 66 Elliptio dilatata 68 Epioblasma flexuosa 170 Epioblasma obliquata 164 Epioblasma per sonata 1 70 Epioblasma propinqua 170 Epioblasma rangiana 168 Epioblasma sampsonii 170 Epioblasma torulosa 166 Epioblasma triquetra 1 62 False mapleleaf 28 Fanshell 102 Fat pocketbook 128 Fatmucket 150 Fawnsfoot 116 Fingemailclam 172 Flat floater 76 Flat pigtoe 58 Floater 78 Fluted-shell 94 192 Mussels of the Midwest Fluter 40 Fragile heelsplitter 122 Fragile papershell 120 Fusconaia ehena 42 Fusconaia flava 46 Fusconaia subrotunda 44 Giant floater 78 Glassyback 108 Golf stick 112 Grandmaw 88, 128, 156, 158 Grass mucket 104,150 Hackle-back 92 Hatchet-back 124 Heelsplitter 76 Hemistena lata 70 Hickory nut shell 28 Hickorynut 108 Higgins eye 152 Hogshell 78 Honest John 136 Horn shell 72 Homy back 100 Kidneyshell 98 Knobbed rock shell 34 Lady finger 68 Lady’s slipper 136 Lampsilis abrupta 154 Lamp silis car dium 156 Lampsilis fasciola 160 Lampsilis higginsi 152 Lampsilis ovata 158 Lampsilis siliquoidea 150 Lampsilis teres 148 Lasmigona complanata 92 Lasmigona compressa 96 Lasmigona costata 94 Leafshell 170 Leptodea fragilis 120 Leptodea leptodon 1 1 8 Ligumia recta 1 36 Ligumia subrostrata 138 Lilliput 130 Little pocketbook 1 16 Little purple 132 Little spectaclecase 146 Long John 136 Long-solid 44 Luster shell 148 Mapleleaf 30 Megalonaias nervosa 24 Missouri mapleleaf 48 Monkeyface 34 Mucket 104 Mule’s ear 66 Musculium 172 Narrow papershell 118 Nodule shell 36 Northern clubshell 56 Northern riffleshell 168 Nutclam 172 Obliquaria reflexa 100 Obovaria olivaria 108 Obovaria retusa 112 Obovaria subrotunda 1 1 0 Ohio fanshell 102 Ohio mucket 154 Ohio pigtoe 62 Orange-foot pimpleback 54 Orange-footed pearlymussel 54 Pancake 92, 124 Paper floater 74 Paper pondshell 74 Papershell 74, 78, 120, 122 Peaclam 172 Pee wee 164 Peanut 26 Pigtoe 44, 46, 60, 62 Pillclam 172 Pimpleback 36, 38, 102 Pink heelsplitter 124 Pink mucket 154 Pink papershell 122 Pink pigtoe 58, 64 Pisidium 172 Pistolgrip 26 Plain pocketbook 156 Plethobasus cicatricosus 52 Plethobasus cooperianus 54 Plethobasus cyphyus 50 Pleurobema clava 56 Index 193 Pleurobema coccineum 58 Pleurobema cordatum 62 Pleurobema plenum 60 Pleurobema rubrum 64 Pocketbook 128, 156, 158 Pondhom 72 Pondmussel 138 Potamilus alatus 124 Pot ami l us capax 1 2 8 Potamilus ohiensis 1 22 Potamilus purpuratus 126 Ptychobranchus fasciolaris 98 Pugnose mucket 1 50 Purple heelsplitter 124 Purple lilliput 132 Purple pimpleback 48 Purple pocketbook 126 Purple wartyback 48 Purple-tip 40 Pyganodon grandis 78 Pyramid pigtoe 64 Quadrula cylindrica 32 Quadrula fragosa 28 Quadrula metanevra 34 Quadrula nodulata 36 Quadrula pustulosa 38 Quadrula quadrula 30 Queen 88 Rabbitsfoot 32 Rainbow 144 Rainbow shell 144 Rayed bean 142 Razorback 92 Ring pink 112 Ringed wartyback 102 Rock-pocketbook 88 Rockshell 88 Rough pigtoe 60 Round combshell 170 Round hickorynut 110 Round pigtoe 58 Round-solid 44 Salamander mussel 90 Sand clam 148 Sand mussel 94 Scaleshell 118 Sharp-ridged pocketbook 158 Sheepnose 50 Simpsonaias ambigua 90 Simpson’s shell 90 Slippershell mussel 86 Slopbucket 78 Slough sandshell 78 Sloughfoot 82 Smooth cob shell 32 Smooth minishell 90 Snuffbox 162 Solid pigtoe 58 Southern pocketbook 158 Sow’s ear 136 Spectaclecase 22 Spectaclecase mussel 32 Sphaeriidae 172 Sphaerium 172 Spike 68 Square mucket 154 Squawfoot 82, 94 Steamboat mucket 104 Stout floater 78 Strange floater 82 Stranger 30 Strophitus undulatus 82 Tan mucket 154 Tennessee riffleshell 170 Texas lilliput 134 Three dot 1 00 Three knot 100 Threehom wartyback 100 Threeridge 40 Toxolasma lividus 132 Toxolasma parvus 130 Toxolasma texasensis 134 Tritogonia verrucosa 26 Truncilla donaciformis 116 Truncilla truncata 114 Tubercled blossom 166 Turkey wing 26 Two-homed pocketbook 36 Uniomerus tetralasmus 72 Utterbackia imbecillis 74 194 Mussels of the Midwest Venustaconcha ellipsiformis 140 Villosa fahalis 142 Villosa iris 144 Villosa lienosa 146 Wabash riffleshell 170 Wabash pigtoe 46 Warty pigtoe 38 Wartyback 36, 38 Washboard 24 Wavy-lined lampmussel 160 Wavy-rayed lampmussel 160 Western pondmussel 138 Western sand shell 138 White heelsplitter 92 White wartyback 52 White-mouth riffleshell 168 Winged mapleleaf 28 Winged orb shell 36 Winged pimpleback 36 Yellow sandshell 148 Zebra mussel 176