Missouri Department of Conservation
Missouri Department of Conservation

Taxonomy

Common Name: SCALESHELL

Phylum: MOLLUSCA

Class: BIVALVIA

Order: UNIONOIDA

Family: UNIONIDAE

Genus: POTAMILUS

Species: LEPTODON

Taxonomic Authority: (RAFINESQUE)

Taxonomy References: 013 , 001

Status

FEDERAL ENDANGERED
STATE ENDANGERED
STATE RANK S1
GLOBAL RANK G1

Status References: 002 , 004

Habitat Summary

"Occurs in clear, nonpolluted riffles with moderate current and firm gravel, cobble or sand substrates."

Primary Habitat: "Aquatic - river/stream"

References: 008 , 009 , 010 , 003

Distribution

General Occurrence in State:

"Is found in the Gasconade and Meramec river basins."

County Occurance

County Occurence
Known Likely Unknown Not Likely Historic Extirpated
CALLAWAY ADAIR TANEY
COLE ANDREW
CRAWFORD ATCHISON
FRANKLIN AUDRAIN
GASCONADE BARRY
JEFFERSON BARTON
LACLEDE BATES
MARIES BENTON
OSAGE BOLLINGER
PULASKI BOONE
ST. LOUIS BUCHANAN
STONE BUTLER
WRIGHT CALDWELL
CAMDEN
CAPE GIRARDEAU
CARROLL
CARTER
CASS
CEDAR
CHARITON
CHRISTIAN
CLARK
CLAY
CLINTON
COOPER
DADE
DALLAS
DAVIESS
DEKALB
DENT
DOUGLAS
DUNKLIN
GENTRY
GREENE
GRUNDY
HARRISON
HENRY
HICKORY
HOLT
HOWARD
HOWELL
IRON
JACKSON
JASPER
JOHNSON
KNOX
LAFAYETTE
LAWRENCE
LEWIS
LINCOLN
LINN
LIVINGSTON
MACON
MADISON
MARION
MCDONALD
MERCER
MILLER
MISSISSIPPI
MONITEAU
MONROE
MONTGOMERY
MORGAN
NEW MADRID
NEWTON
NODAWAY
OREGON
OZARK
PEMISCOT
PERRY
PETTIS
PHELPS
PIKE
PLATTE
POLK
PUTNAM
RALLS
RANDOLPH
RAY
REYNOLDS
RIPLEY
SALINE
SCHUYLER
SCOTLAND
SCOTT
SHANNON
SHELBY
ST. CHARLES
ST. CLAIR
ST. FRANCOIS
STE. GENEVIEVE
STODDARD
SULLIVAN
TEXAS
VERNON
WARREN
WASHINGTON
WAYNE
WEBSTER
WORTH

References for distribution: 008 , 009 , 010 , 003 , 004

Distribution by Watersheds

Meramec R.
Bourbeuse R.
Big R.
Gasconade R. from Headwaters to Big Piney R.
Gasconade R. from Big Piney R. to Mo. R.

Comments: ""

Distribution by Ecoregions

Ozark Highlands

Comments: ""

Distribution by Potential Natural Vegetation

Oak-Hickory Forest

Distribution by Natural Divisions of Missouri

Ozark Border: Missouri River
Ozark Border: Mississippi River
Ozark: Upper Ozark

Habitat Associations

Species is associated with "Aquatic" habitats.

National Wetlands Inventory Association:

Riverine

Aquatic Associations:

"Riverine, lower perennial", "Unconsolidated bottom, cobble/gravel",
"Riverine, lower perennial", "Unconsolidated bottom, sand",

References for Aquatic Associations: 008 , 009 , 010 , 003

Habitat Types:

Permanent Stream

References for Habitat Types: 008 , 009 , 010 , 003

Terrestrial Natural Communities:

References for Terrestrial Natural Communities:

Food Habits

Trophic Level:

"Omnivore"

Larval Food Habits

Comments for larval food habits:
""

References for larval food habits:

Juvenile Food Habits

Comments for Juvenile Food Habits:
""

References Juvenile Food Habits

Adult Food Habits

Algae; Not Specified
Protozoans; Not Specified
Other Microorganisms; Not Specified
Bacillariophyceae (diatoms); Not Specified

Comments for Adult Food Habits:
""

References Adult Food Habits 011

Niche Requirements

Egg Niche Requirements

References for egg niches requirements:

Feeding Larvae Niche Requirements

References for feeding larvae niche requirements:

Resting Larvae Niche Requirements

References for resting Larvae niche requirements:

Feeding Juvenile Niche Requirements

References for feeding juvenile niche requirements:

Resting Juvenile Niche Requirements

References for resting juvenile niche requirements:

Breeding Adult Niche Requirements

References for feeding Adult niche requirements:

Feeding Adult Niche Requirements

References for feeding adult niche requirements:

Resting Adult Niche Requirements

References for resting adult niche requirements:

Niche Requirement Summary

Current velocity specified in comments(00150)
Elevation specified in comments(00240)
Gradient specified in comments(00140)
Host specified in comments(00680)
Substrate specified in comments(00080)
Water depth specified in comments(00230)

Comments about Life History:

Code Comment
007 Spawns in early to mid-August *09*.
003 Fish host for glochidia is the freshwater drum *012*.
020 Eggs are fertilized and develop into glochidia in gills of female *03*.
034 Limited by availability of suitable habitat and presence of host species *03*.
035 Regulatory factors include predation *03*.
037 Depend on host for dispersal *03*.

Life History Information

Limiting factors specified in comments(034)
Regulatory factors specified in comments(035)
Dispersal specified in comments(037)
Origin in state: native
Seasonal distribution in state: all seasons
Closely associated plant or animal species specified in comments(003)
Foraging strategy: filtering
Foraging sites: water
Breeding season specified in comments(007)
Duration of pair bond: no pair bond formed
Development of young at birth/hatching specified in comments(020)

Comments about Life History:

Code Comment
007 Spawns in early to mid-August *09*.
003 Fish host for glochidia is the freshwater drum *012*.
020 Eggs are fertilized and develop into glochidia in gills of female *03*.
034 Limited by availability of suitable habitat and presence of host species *03*.
035 Regulatory factors include predation *03*.
037 Depend on host for dispersal *03*.

References for life history: 009 , 003 , 005 , 006 , 007

Management

Beneficial Management Practices:

Water - control sedimentation
Water - control pollution (thermal, physical, chemical)
Water - stabilize streambanks
Grassland - maintain stream banks
Grassland - maintain streamside vegetation

Beneficial Management References: 009

Adverse Managment Practices:

Water - dredging and filling

Adverse Management References: 009

Comments on Management:
No work should be allowed below the high bank of the stream between May 1 and August 15, to allow for successful reproduction and recruitment. Take precautions to prevent spread of zebra mussels *009*.

References for Management Comments: 009

References

Reference Code Citation
001 Williams, J.D., A.E. Bogan, R.S. Butler, K.S. Cummings, J.T. Garner, J.L. Harris, N.A. Johnson and G.T. Watters. 2017. A revised list of the freshwater mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada. Freshwater Mollusk Biology and Conservation 20:33-58.
002 Missouri Natural Heritage Program. 2007. Missouri Species and Communities of Conservation Concern Checklist. Missouri Department Of Conservation. Jefferson City, Missouri. 51 Pp.
003 Oesch, R.D. 1995. Missouri Naiades. A Guide To The Mussels Of Missouri. Second Edition. Missouri Dept. Of Conservation. Jefferson City, Missouri. 271 Pp.
004 Unpb Missouri Department of Conservation Heritage Database. P.O. Box 180, Jefferson City, Mo 65102.
005 Baker, F.C. 1928. The fresh-water mollusca of Wisconsin. Part II. Pelecypoda. Bull. Univ. Wisconsin, Bull. 70, II. WI Geol. and Nat. Hist. Surv. Gen. Ser. 1301, 495 pp. (cited in ref. 001)
006 Fuller, S.L.H. 1978. Fresh-water mussels (Mollusca: Bivalvia: Unionidae) of the Upper Mississippi River: Observations at selected sites within the 9-foot channel navigation project on behalf of the Unites States Army Corps of Engineers. Acad. Nat. Sciences. Philadelphia, PA. 401 pp. (cited in ref. 003).
007 Brynildson, I. 1985. Freshwater mussels of the Upper Mississippi River. Wisc. Dept. Nat. Resources. 63 pp.
008 Buchanan, A. C. 1980. Mussels (naiades) of the Meramec River Basin. Missouri Dept. of Conservation Aquatic Ser. No. 17. Jefferson City, MO. 76 pp.
009 Missouri Department of Conservation. Best Management Practices: Scaleshell mussel. Missouri Dept. of Conservation. Jefferson City, MO.
010 Unpb Bruenderman, S. Mussel Occurrence Database. Missouri Dept. Of Conservation, 1110 S. College Ave., Columbia, Mo 65201 (573-882-9880).
011 Allen, W.R. 1914. The Food And Feeding Habits Of Freshwater Mussels. Biol. Bull. 27(3):127-139.
012 Unpb Faiman, S. Missouri Department of Conservation, 1110 S. Collge Ave., Columbia, MO 65201, 573-882-9909.
013 Freshwater Mollusk Conservation Society (FMCS). 2021. The 2021 checklist of freshwater mussels. https://molluskconservation.org/Library/Committees/Names/Appendix_1_Bivalves_Revised_Names_List_20210825.pdf