(DRAFT) - Taxonomy
                           Species MUSSEL, PEARLY, CURTIS'
                                Species Id ESIS403002
                                   Date 13 MAR 96



TAXONOMY

NAME - MUSSEL, PEARLY, CURTIS' OTHER COMMON NAMES - MUSSEL, PEARLY, CURTIS';MUSSEL, PEARLY, CURTIS; PEARLYMUSSEL, CURTIS; MUSSEL, PEARLY+ and CURTIS ELEMENT CODE - CATEGORY - Aquatic Molluscs PHYLUM AND SUBPHYLUM - MOLLUSCA, CLASS AND SUBCLASS - BIVALVIA, ORDER AND SUBORDER - UNIONOIDA, FAMILY AND SUBFAMILY - UNIONIDAE, GENUS AND SUBGENUS - EPIOBLASMA, SPECIES AND SSP - FLORENTINA, CURTISI SCIENTIFIC NAME - EPIOBLASMA FLORENTINA CURTISI AUTHORITY - TAXONOMY REFERENCES - COMMENTS ON TAXONOMY - Curtis' Pearly Mussel Epioblasma florentina curtisi (Utterback, 1916) KINGDOM: Animal GROUP: Clam PHYLUM: Mollusca CLASS: Bivalvia ORDER: Unionoida FAMILY: Unionidae The Curtis' pearly mussel was first described from specimens collected in the White River at Hollister, MO (01): "Nutritive Structures: Branchial opening densely bordered with papillae; anal crenulated; supra-anal high, rather small, separated from anal by moderately short mantle connection, mantle border here spotted; inner laminae of inner gills entirely connected to visceral mass; palpi very small connected only by their anterior base which is remote from the anterior attachment of pointed outer gill; color of soft parts grayish except the blackish mantle edge at siphonal openings. "Reproductive Structures: Marsupium very broad, rounded ventrad, kidney-shaped, ovisacs several, distinct occupying posterior half of outer gills and distended into beaded, unpigmented structures along Taxonomy - 1 (DRAFT) - Taxonomy Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 ventral edge when gravid; conglutinates broken masses; glochidia unknown as only specimens gravid with early embryos have been obtained; inner mantle edge of female antero-ventrad to branchial opening drawn in toward the interior of shell forming a chamber." Shell Characters: The shell is small, usually less than 1 1/2 inches (39 mm) in length. Males are slightly larger than females (mean length 31.5 mm and 28.1 mm, respectively). The ratio of shell length to shell height to shell breadth is 6:4:3 (02). In the males, the shell is oval in shape, with the anterior end smoothly rounded, and the posterior end bluntly pointed and biangular. There is generally a slight but wide indentation on the posterior-ventral margin where the double, barely discernible posterior ridge joins the ventral margin (02). The female shell is smoothly rounded anteriorly and broadly rounded and inflated posteriorly. The posterior edge of the shell is serrated. The annual growth lines are deeply incised (02). The shell of both sexes is yellowish brown to brown, usually light brown, sometimes with fine, evenly spaced rays over most of its length. The beaks are broad and low and the beak sculpture is typically eroded away (02). Utterback (01) describes the beak sculpture as heavily ridged, tending towards double-looped. The interior of the shell is white to whitish-blue, with the periostracum frequently showing through the nacre, particularly in the beaks and posterior half of the shell (02). Beak cavities are broad and relatively shallow. The pallial line, often indistinct when present, is one-third of the height of the shell above the ventral margin. The hinge line is broadly curved. Muscle scars are located against the hinge line. Anterior scars are deeply impressed and touch the cardinal teeth, while posterior muscle scars are barely discernible. Two high, blade-like, short (one-third of the shell length) lateral teeth are found in the left valve, and one high blade-like lateral tooth is in the right valve. Lateral teeth are separated from the cardinal teeth by approximately half the laterals' length. Cardinal teeth are high, triangular, and divergent, one in the right valve and two in the left valve. Epioblasma florentina curtisi was first named Truncilla curtisii (Frierson and Utterback, 1916). Other scientific names used for this species in the literature include: Epioblasma curtisi, Dysnomia florentina curtisi, Dysnomia curtisi, and Plagiola florentina (Lea). Clark (03) gives a brief explanation of the rationale for using Epioblasma rather than other generic names for this species. Other common names used in the literature for this subspecies include Curtis pearly mussel (used by IUCN) and Curtis pearlymussel (09). The type specimens have been lost. Lectotypes selected by Richard Johnson (04) are stored at the Museum of Zoology, University of Michigan. Sketches or photographs of this species can be found in Utterback (01), Johnson (04), or Buchanan (02). Series of this species are stored at the University of Michigan Museum of Zoology, the Ohio State University Museum of Zoology, and possibly several other locations. Taxonomy - 2
                                  (DRAFT) - Status
                           Species MUSSEL, PEARLY, CURTIS'
                                Species Id ESIS403002
                                   Date 13 MAR 96



STATUS

Coded Status Arkansas; Federal Endangered Arkansas; State Recognized E: Federal Endangered Commercial COMMENTS ON STATUS - U.S. STATUSES AND LAWS: The Curtis' pearly mussel (Epioblasma florentina curtisi) has been designated as Endangered pursuant to the Endangered Species Act of 1973 (50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540), as amended. The subspecies has this status wherever found including the States of AR and MO. Critical Habitat has not been designated. This subspecies is protected by the Lacey Act (P.L. 97-79, as amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import, export, transport, sell, receive, acquire, or purchase any wild animal (alive or dead including parts, products, eggs, or offspring): (1) in interstate or foreign commerce if taken, possessed, transported or sold in violation of any State law or regulation, or foreign law; or (2) if taken or possessed in violation of any U.S. law, treaty, or regulation or in violation of Indian tribal law. It is also unlawful to possess any wild animal (alive or dead including parts, products, eggs, and offspring) within the U.S. territorial or special maritime jurisdiction (as defined in 18 U.S.C. 7) that is taken, possessed, transported, or sold in violation of any State law or regulation, foreign law, or Indian tribal law. RESPONSIBLE FEDERAL AGENCIES: USFWS -Responsible for the management/recovery, listing, and law enforcement/protection of this species. USFS -Responsible for the law enforcement/protection of this species with applicable State and Federal laws on public lands under their control. Also responsible for management/recovery on Forest Service lands. The Forest Service is responsible for integrating management, protection, and conservation of Federally listed species into the Forest Planning process (36 CFR 219.19 and 219.20). Management practices that would cause detrimental changes in water temperature or composition, water course blockage, or sediment deposits within 100 feet of the edges of perennial Status - 1 (DRAFT) - Status Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 streams, lakes or other bodies of water are prohibited (36 CFR 219.27(e)). All Federal agencies have responsibility to ensure that any action authorized, funded, or carried out by that agency is not likely to jeopardize the continued existence of the species or result in the destruction or adverse modification of Critical Habitat (50 CFR 402), and to utilize their authorities to carry out programs for the conservation of the species. STATE STATUSES AND LAWS: STATE: Arkansas DESIGNATED STATUS: Recognized Endangered ADMINISTRATIVE AGENCY: Arkansas Game and Fish Commission STATE STATUTE: Amendment 35, AR Constitution; Cooperative Agreement with USFWS, effective June 23, 1976. STATE: Missouri DESIGNATED STATUS: Endangered ADMINISTRATIVE AGENCY: Missouri Department of Conservation STATE STATUTE: Rev. Stat. of MO, Ch. 252; Wildl. Code of MO (3 Code of State Regs. 4.111). INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS: The Curtis' pearly mussel, Epioblasma florentina curtisi, is listed in Appendix I of CITES. The Curtis pearly mussel is also listed as endangered at the specific level (E. florentina) in the IUCN Invertebrate Red Data Book, 1983; and the 1986 IUCN Red list of Threatened Animals. ECONOMIC STATUSES: This mussel has been exported for use in the shelling industry. 74/10/17:39 FR 37078/37079 - Review of status 75/09/26:40 FR 44329/44333 - Proposed rule, list as Endangered 76/06/14:41 FR 24064/24067 - Final rule, listed as Endangered 81/02/27:46 FR 14652/14658 - Five-year review 87/07/07:52 FR 25523/25528 - Notice of review Status - 2
     

HABITAT ASSOCIATIONS

HABITAT - AQUATIC INLAND AQUATIC LAND USE - Residential Cropland and Pasture Deciduous Forest Land Streams and Canals Nonforested Wetland NATIONAL WETLAND INVENTORY CODES NWI NWICLS NWIMOD NWISPEC Riverine, upper perennial UB2 Riverine, upper perennial UB1 Riverine, upper perennial SB2 Riverine, upper perennial SB1 Riverine, upper perennial RB2 Riverine, upper perennial AB4 COMMENTS ON HABITAT ASSOCIATIONS - Epioblasma florentina curtisi (Curtis' pearly mussel) is found in inland freshwater streams. It occurs in stream reaches which are transition areas between headwater and lowland stream reaches. This species has been found in Ozark streams in areas of oak-hickory forests. Surrounding habitat includes farmland, forest land and small towns. Farm crops include milo and soybeans. Curtis' pearly mussel does best in areas not impacted by agricultural activities. Epioblasma florentina curtisi has been found in order 4 to 7 streams with gradients of 0.9 to 8.0 feet per mile, in stable substrates of sand and gravel to gravel, cobble and boulder, in riffles or runs (05). Mean particle size of ths substrate where this species is found, based on substrate analysis in the Little Black River, ranges from small gravel to cobble (06). It is found in 2 to 30 inches of water in slow current (less than 0.06 ft/sec. to 0.7 ft/sec. at the bottom) (05,06). It prefers flowing waters and is not found in stagnant pools. They frequently occur near beds of waterwillow (Justicia americana) and white water lily (Nymphaea odorata) may be present. In the section of Little Black River where this species occurs, total hardness ranged from 86 to 205 mg/l, and specific conductance from 110 to 165 umhos/square cm. It normally occurs in well buffered waters (06). Historically, it has been found between 315 and 642 feet above mean sea level. It presently is found between 315 and 381 feet above mean sea level. Habitat Associations - 1
                                (DRAFT) - Food Habits
                           Species MUSSEL, PEARLY, CURTIS'
                                Species Id ESIS403002
                                   Date 13 MAR 96



FOOD HABITS

TROPHIC LEVEL - OMNIVORE LIFESTAGE FOOD FOOD PART General Detritus General Bacteria General Phytoplankton General Zooplankton General Fish Food Habits - 1
                         (DRAFT) - Environment Associations
                           Species MUSSEL, PEARLY, CURTIS'
                                Species Id ESIS403002
                                   Date 13 MAR 96



ENVIRONMENTAL ASSOCIATIONS

G = General A = Adult LIM = Limiting RA = Resting Adult J = Juvenile FA = Feeding Adult RJ = Resting Juvenile BA = Breeding Adult FJ = Feeding Juvenile P = Pupae L = Larvae E = Egg RL = Resting Larvae FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS G Aquatic Features: Pool areas Environment Associations - 1
                               (DRAFT) - Life History
                           Species MUSSEL, PEARLY, CURTIS'
                                Species Id ESIS403002
                                   Date 13 MAR 96



LIFE HISTORY

FOOD HABITS: Like other freshwater naiades, the Curtis' pearly mussel is a filter feeder which removes organic debris, phytoplankton, zooplankton, and possibly bacteria from the water for food (07). Glochidia (parasitic larval stage) are obligate parasites on the skin, fins or gills of fish (02). Very little specific information is available on food items or food preferences. HOME RANGE/TERRITORY: Epioblasma florentina curtisi is nonterritorial. It is normally found imbedded in the stream bottom and probably exhibits very little lateral motion. When disturbed, individuals may move up to several feet. Females move onto the surface of the substrate in order to release larvae (glochidia) (02). Interspecific and intraspecific territorial interaction are doubtful. PERIODICITY: E. f. curtisi is a cold-blooded animal whose level of activity is strongly influenced by water temperature, but is generally regarded as sessile. This species, like all mussels, is most active during periods when the water temperature is greater than 50 degrees F. Females appear to be more active during the spring reproduction period (02). MIGRATION PATTERNS: Non-migratory. COVER/SHELTER REQUIREMENTS: E. f. curtisi is generally found imbedded in the substrate in shallow (2 to 30 inches) riffles and runs. They frequently occur near beds of waterwillow (Justicia americana) and white water lily (Nymphaea odorata) may be present. REPRODUCTIVE SITE REQUIREMENTS: This species reproduces in the same habitat where it is found throughout the year. Epioblasma florentina curtisi is found in inland freshwater streams. It occurs in stream reaches which are transition areas between headwater and lowland stream reaches. This species has been found in Ozark streams in areas of oak-hickory forests. Surrounding habitat includes farmland, forest land and small towns. Farm crops include milo and soybeans. Curtis' pearly mussel does best in areas not impacted by agricultural activities. Epioblasma florentina curtisi has been found in order 4 to 7 streams with gradients of 0.9 to 8.0 feet per mile, in stable substrates of sand and gravel to gravel, cobble and boulder, in riffles or runs (05). Mean particle size of ths substrate where this species is found, based on substrate analysis in the Little Black River, ranges from small gravel to cobble (06). It is found in 2 to 30 inches of water in slow current (less than 0.06 ft/sec. to 0.7 ft/sec. at the bottom) (05,06). It prefers flowing waters and is not Life History - 1 (DRAFT) - Life History Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 found in stagnant pools. In the section of Little Black River where this species occurs, total hardness ranged from 86 to 205 mg/l, and specific conductance from 110 to 165 umhos/square cm. It normally occurs in well buffered waters (06). Historically, it has been found between 315 and 642 feet above mean sea level. It presently is found between 315 and 381 feet above mean sea level. REPRODUCTIVE CHARACTERISTICS: The Curtis' pearly mussel is assumed to have a life cycle similar to that of other naiades, which is as follows: Males eject sperm directly into the water. The female holds eggs in her gills where they are fertilized by sperm taken in with water during siphoning. These eggs develop into glochidia (the parasitic larval stage) in a modified portion of the gills called the marsupium. Fully developed glochidia are discharged directly into the water by the female. If a glochidium comes into contact with an appropriate fish host, it attaches to the fish's skin, fins, or gills and begins its parasitic stage. Glochidia live on the fish host for a week to several months. Eventually glochidia transform into juvenile naiades and drop from the fish (02). The specific host of the Curtis' pearly mussel is not known. The eggs of this species are fertilized in the fall, develop through the winter, and mature glochidia are released in early spring (02). PARENTAL CARE: After being fertilized, the eggs are retained by the female in a modified portion of the outer gills called the marsupium. Here the eggs develop into the larval stage (glochidia). Once the glochidia are released from the female, they receive no parental protection (08). POPULATION BIOLOGY: E. f. curtisi is primarily limited by habitat. It requires shallow flowing riffles and runs and relatively unpolluted water. Much of the original habitat in which this species occurred has been inundated by waters dammed for flood control, water supply, hydropower production, and recreation (05). Dam construction has eliminated flowing water habitat resulting in stagnation of bottom waters and accumulation of silt and organic matter, altered food supplies and possibly eliminated fish hosts or restricted their movement. Stream channelization and gravel dredging have reduced substrate variability and stability. Poor land management practices have increased sitlation (02). This species may also be limited by host fish and in the Castor River and Cane Creek, reproduction may be limited by low density of mature individuals (02). Little is known about recruitment and mortality rates. SPECIES INTERRELATIONSHIPS: The larval stage (glochidia) of the Curtis' pearly mussel is assumed to be parasitic on one or more species of fish. The host(s) is not presently known (02). OTHER LIFE HISTORY DESCRIPTORS: Life History - 2 (DRAFT) - Life History Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 None. Life History - 3
                           (DRAFT) - Management Practices
                           Species MUSSEL, PEARLY, CURTIS'
                                Species Id ESIS403002
                                   Date 13 MAR 96



MANAGEMENT PRACTICES

RESULT MANAGEMENT PRACTICE Beneficial Developing/maintaining stream structures Beneficial Maintaining/Controlling Water Flow Beneficial Maintaining undisturbed/undeveloped areas Beneficial Restricting/regulating human use of habitats Beneficial Land Acquisition Beneficial Controlling pollution [thermal, chemical, physical] Beneficial Stocking captive-reared wild-strain animals Beneficial Transplanting wild animals Adverse Low Gene Pool Existing Low Gene Pool Adverse Siltation Existing Siltation Adverse Reservoirs Existing Reservoirs Adverse Migration barriers Existing Migration barriers Adverse Dredging Existing Dredging Adverse Applying fertilizers Existing Applying fertilizers Adverse Applying herbicides Existing Applying herbicides Adverse Applying pesticides Existing Applying pesticides Adverse Environmental Contamination/Pollution Existing Environmental Contamination/Pollution Adverse Erosion Existing Erosion Adverse Existing Adverse Harvesting Existing Harvesting COMMENTS ON MANAGEMENT PRACTICES - The Curtis' pearly mussel (Epioblasma florentina curtisi) appears to be primarily limited by habitat. This species occurs in relatively clear, shallow (less than 3 1/2 feet), flowing water in upland stream reaches which serve as transition areas between headwater and lowland reaches (05). Therefore, this species cannot survive in impounded waters. Much of the original habitat in which this species occurred has been inundated by waters dammed for flood control, water supply, hydropower production, and recreation (05). Dam construction has eliminated flowing water habitat resulting in stagnation of bottom waters and accumulation of silt and organic matter, altered food supplies, and possibly eliminated fish hosts or restricted their movement. Reservoir construction on White River caused the disappearance of E. f. curtisi from that stream (05). Construction and operation of Management Practices - 1 (DRAFT) - Management Practices Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 Clearwater Dam probably contributed to the disappearance of this species from Black River (05). Since closure of the dam, flow characteristics downstream in the Black River have changed. Reduced maximum annual flows, reduced mean daily flows in Spring and increased mean daily flow in Summer may have at times exposed naiades causing dessication, temperature stress, and increased exposure to predators; impacted reproduction through water temperature changes; and impacted fish hosts (02). Increased siltation and nutrient loads resulting from forest clearing and agricultural practices may also have contributed to this species decline (02). The use of pesticides also may have been and may still be a contributing factor as is dredging of sand and gravel from streams which reduces substrate variability and stability (05). The Curtis' pearly mussel's reproduction may be limited by low density of mature individuals (02). This species may also be limited by host fish and in the Castor River and Cane Creek, reproduction may be limited by low density of mature individuals (02). Curtis' pearly mussel populations in Little Black River may be adversely impacted by a flood control project as well as continued forest clearing and agricultural activities. Agricultural practices, urban encroachment, and low reproductive potential will continue to impact this species in Castor River (02). APPROVED PLAN: U.S. Fish and Wildlife Service. 1986. Curtis' Pearly Mussel Recovery Plan. U.S. Fish and Wildl. Serv., Twin Cities, MN. 92 pp. Epioblasma florentina curtisi shall be considered recovered when 1) viable reproducing populations occur in four streams sufficiently separate so that a single catastrophic event would be unlikely to affect more than one population, 2) provisions have been made to prevent any future man-made changes (dam construction, channelization, in-stream gravel dredging, etc.) that have the potential to adversely affect mussels in those streams (i.e., the riverways themselves are protected from significant changes due to industry, agriculture, or other forms of human encroachment and development), and 3) the four populations are protected by some form of riparian protected zone. Actions recommended to prevent extinction and facilitate recovery include: A. Protect populations of E. f. curtisi by preventing adverse alteration of existing habitat (such as development) by establishing riparian protected zones and utilizing land protection planning. 1. Habitat needs must be further defined. 2. Review proposals for actions upon habitat and require modification to minimize or eliminate any adverse impacts. Such impacts might include reduction of stream flows, changes in aquatic organism composition, food supply reduction, sediment load, and water chemistry due to dam construction; and increased pollution from pesticide use or other environmental contaminants associated with human Management Practices - 2 (DRAFT) - Management Practices Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 developments. 3. Develop land protection plans. 4. Use purchase, lease, or other means to protect riparian zones from adverse impacts. 5. Monitor habitat and populations in protected areas. B. Enhance existing populations through habitat and population management. 1. Determine which populations are habitat-limited, evaluate habitat conditions and reduce or eliminate those factors limiting population levels. 2. Determine population levels of standing stocks, the status of reproduction in those stocks, and the number of individuals necessary to constitute a viable population. Develop artificial culture and transplantation techniques. Enhance the status of density-limited populations by introduction of wild individuals or artificially cultured juveniles or adults. 3. Periodically evaluate enhancement efforts. C. Restore viable populations of E. f. curtisi to present and former range using the same techniques for reintroduction as were used to enhance existing populations (See secton B above). Management Practices - 3
                                   (DRAFT) - References
                             Species MUSSEL, PEARLY, CURTIS'
                                  Species Id ESIS403002
                                      Date 13 MAR 96



     

References

***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE ***** 01 Utterback, W.I. 1915. The naiades of Missouri. Am. Midl. Nat. 4(3-8):200. 02 U.S. Fish and Wildlife Service. 1985. A Recovery Plan for the Curtis' Pearly Mussel, Epioblasma florentina curtisi (Utterback, 1915). Draft. U.S. Fish and Wildl. Serv., Twin Cities, MN. 26 pp. 03 Clarke, A.H. 1981. Determination of the precise geographical areas occupied by four endangered species of freshwater mollusks. Final Rep., USFWS, Contr. #14-16-003-81-019. 62 pp. 04 Johnson, R.I. 1978. Systematics and zoogeography of Plagiola (=Dysnomia=Epioblasma) an almost extinct genus of freshwater mussels (Bivalvia:Unionidae) from Middle North America. Bull. Mus. Comp. Zool. 148(6):239-321. 05 Buchanan, A.C. 1983. Distribution, abundance, status, and habitat of the Curtis' pearly mussel Epioblasma florentina curtisi in southern Missouri. U.S. Fish & Wildl. Serv., Endang. Sp. Proj. SE-3-1. 10 pp. 06 Buchanan, A.C. 1982. A study of Epioblasma florentina curtisi (Utterback 1915), the Curtis' pearly mussel, in the Upper Little Black River, Missouri. USDA, Soil Conserv. Serv., Columbia, MO. 11 pp. 07 Buchanan, A.C. 1983. An evaluation of the potential impacts of SCS structures B-9 and C-7 upon the Curtis' pearly mussel, Epioblasma florentina curtisi (Utterback 1915), in the Upper Little Black River, Missouri. Missouri Dept. of Conservation, 1110 College Ave., Columbia, MO 65201. 18 pp. 08 Stein, C.B. 1971. Naiad life cycles. Their significance in the conservation of the fauna. Pages 19-25. IN: Proceed. of a Symp. on Rare and Endangered Mollusks (naiades) of the U.S. S.E. Jorgnesen and R.W. Sharp, eds. U.S. Fish & Wildl. Serv., Minn. - St. Paul, MN. 25 pp. 09 Committee on Scientific and Vernacular Names of Mollusks. 1986. A list of common and scientific names of aquatic invertebrates from the United States and Canada - Mollusca. Draft. Am. Fish. Soc., Spec. Publ., Bethesda, MD. 156 pp. ***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY ***** 01 Buchanan, A.C. 1983. A survey of the Curtis' pearly mussel Epioblasma florentina curtisi (Utterback, 1915), in southern Missouri. Final Rept., Endang. Species Proj. SE-3-1. 10 pp. 02 Oesch, R.D. 1984. Missouri naiades. A guide to the mussels of Missouri. Missouri Dept. Conserv., Jefferson City, MO. 03 Stansbery, D.H. 1985. Pers. comm. Museum of Zoology, Ohio State University, Columbus. 04 Gordon, M. 1985. Pers. comm. Univ. of Arkansas, Fayetteville. 05 Utterback, W.I. 1915. The naiades of Missouri. Am. Midl. Nat. 4(3-8):200. References - 1 (DRAFT) - References Species MUSSEL, PEARLY, CURTIS' Species Id ESIS403002 Date 13 MAR 96 06 Johnson, R.I. 1978. Systematics and zoogeography of Plagiola (=Dysnomia=Epioblasma) an almost extinct genus of freshwater mussels (Bivalvia:Unionidae) from Middle North America. Bull. Mus. Comp. Zool. 148(6):239-321. 07 Utterback, W.I. 1917. Naiad geography of Missouri. Am. Midl. Nat. 5(1):26-30. 08 Buchanan, A.C. 1979. Mussels (naiades) of the Little Black River Basin in Missouri and Arkansas. USDA, Soil Conserv. Serv., Columbia, MO. 69 pp. 09 Buchanan, A.C. 1982. A study of Epioblasma florentina curtisi (Utterback 1915), the Curtis' pearly mussel, in the Upper Little Black River, Missouri. USDA, Soil Conserv. Serv., Columbia, MO. 11 pp. 10 Miller, A.C. and P.D. Hartfield. 1986. A survey for live mussels in the Black and Spring Rivers, Arkansas. 1985. U.S. Army Corps of Engineers, Misc. Pap. EL-87-7. 13 pp. + tables. 11 Harris, J.L. and M.E. Gordon. 1983. Distribution and status of fourteen species of freshwater mussels considered rare or endangered in Arkansas. Rept. to AR Nat. Heritage Commission. 23 pp + appendices. 12 Miller, A.C. and D.A. Nelson. 1984. A survey for mussels on the Black and Spring Rivers, Arkansas, 16 and 17 November, 1983. Rept. by U.S. Army Corps of Engineers, Waterway Exper. Sta. 9 pp. 13 Gordon, M.E., et al. 1984. Mussel fauna of the Black and Spring Rivers in northeast Arkansas. Rept. to Little Rock Dist., Army Corps of Engineers. 27 pp. References - 2