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Elliptoideus sloatianus

(I. Lea, 1840)

Purple Bankclimber

G2Imperiled Found in 3 roadless areas NatureServe Explorer →
G2ImperiledGlobal Rank
VulnerableIUCN
HighThreat Impact
Purple bankclimber (mussel) (Elliptoideus sloatianus). Photo by U.S. Fish & Wildlife Service, Public Domain (U.S. Government Work), via ECOS.
U.S. Fish & Wildlife Service, https://www.usa.gov/government-works
Identity
Unique IDELEMENT_GLOBAL.2.120124
Element CodeIMBIV15010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryInvertebrate Animal
IUCNVulnerable
Endemicendemic to a single nation
KingdomAnimalia
PhylumMollusca
ClassBivalvia
OrderUnionoida
FamilyUnionidae
GenusElliptoideus
Synonyms
Nephronaias sloatianusI. Lea, 1840Plectomerus sloatianus(I. Lea, 1840)
Other Common Names
purple bankclimber (EN) Purple bankclimber (mussel) (EN)
Concept Reference
Turgeon, D. D., J. F. Quinn, Jr., A. E. Bogan, E. V. Coan, F. G. Hochberg, W. G. Lyons, P. M. Mikkelsen, R. J. Neves, C. F. E. Roper, G. Rosenberg, B. Roth, A. Scheltema, F. G. Thompson, M. Vecchione, and J. D. Williams. 1998. Common and scientific names of aquatic invertebrates from the United States and Canada: Mollusks. 2nd Edition. American Fisheries Society Special Publication 26, Bethesda, Maryland. 526 pp.
Taxonomic Comments
Frierson (1927) created the monotypic subgenus Elliptoideus under Elliptio for this species, although Clench and Turner (1956) considered Elliptiodeus sloatianus an Elliptio. Current authors, however, have given Elliptoideus generic status (e.g., Turgeon et al. 1998). E. sloatianus is monotypic. The use of all four gills for brooding is one diagnostic that separates it from the genus Elliptio. Tentatively placed in the genus Plectomerus following genetic analysis (Serb et al., 2003).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-04-07
Change Date2000-08-31
Edition Date2025-04-07
Edition AuthorsCordeiro, J. (2011); rev. Jackson, D. R. (2014); rev. T. Cornelisse (2025)
Threat ImpactHigh
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences6 - 20
Rank Reasons
This species is imperiled due to its limited distribution and long-term population declines caused by many ongoing threats.
Range Extent Comments
This species occurs in the Apalachicola, Chattahoochee, and Flint River systems in Alabama, Georgia, and Florida, and the Ochlockonee River in Florida and Georgia, USA (Brim Box and Williams 2000; Williams et al. 2008; USFWS 2003, 2020; RARECAT 2025).
Occurrences Comments
This species is found in eight sub-basins, the unit of populations for this species, as defined by the USFWS (USFWS 2020).
Threat Impact Comments
This species is threatened by habitat loss and degradation associated with dams and other waterway barriers, channelization, mining, and dredging operations; pollutants in wastewater discharges, including from sewage treatment plants and industrial operations; runoff of silt, fertilizers, pesticides, and other pollutants from land disturbance activities, such as development and agriculture implemented without adequate measures to control runoff; invasive clams and mussels; and elevated water temperature due to climate change (USFWS 2003, 2020; FNAI 2023).
Ecology & Habitat

Description

See Deyrup and Franz (1994) and Clench and Turner (1956). This species is a heavy-shelled, strongly sculptured mussel. A well-developed posterior ridge extends from the umbos to the posterior ventral margin. The posterior slope and disk just anterior to the posterior ridge are sculptured with several irregular ridges that vary greatly in development. Umbos are low, extending just above the dorsal margin. There is one pseudocardinal tooth in the right valve and two in the left. Lateral teeth are very thick and slightly curved. Nacre color is whitish near the center becoming deep purple towards the margin, and very iridescent posteriorly (Butler and Alam, 1999).

Diagnostic Characteristics

The only large, thick-shelled, highly sculptured, purple-nacred species within its range.

Habitat

This species inhabits medium and large rivers with moderate current in substrates of sand and gravel; although it may survive in some impoundments, adults may be unable to reproduce there (Williams et al. 2014).
Other Nations (1)
United StatesN2
ProvinceRankNative
AlabamaS1Yes
FloridaS1Yes
GeorgiaS2Yes
Threat Assessments
ThreatScopeSeverityTiming
1 - Residential & commercial developmentRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
1.1 - Housing & urban areasRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
7 - Natural system modificationsRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
7.2 - Dams & water management/useRestricted (11-30%)Serious or 31-70% pop. declineHigh (continuing)
8 - Invasive & other problematic species, genes & diseasesRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
8.1 - Invasive non-native/alien species/diseasesRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
8.1.2 - Named speciesRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
9 - PollutionLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
9.1 - Domestic & urban waste waterRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
9.2 - Industrial & military effluentsRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
9.3 - Agricultural & forestry effluentsRestricted (11-30%)Moderate or 11-30% pop. declineHigh (continuing)
11 - Climate change & severe weatherLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)
11.3 - Temperature extremesLarge (31-70%)Moderate or 11-30% pop. declineHigh (continuing)

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Roadless Areas (3)
Florida (3)
AreaForestAcres
Gum BayApalachicola National Forest11,645
Long BayApalachicola National Forest5,726
SavannahApalachicola National Forest1,927
References (41)
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  3. Brim Box, J. and J.D. Williams. 2000. Unionid mollusks of the Apalachicola Basin in Alabama, Florida, and Georgia. Alabama Museum of Natural History Bulletin, 21: 1-143.
  4. Clench, W. J. and R. D. Turner. 1956. Freshwater mollusks of Alabama, Georgia, and Florida from the Escambia to the Suwanee River. Bulletin of the Florida State Museum Biological Sciences 1(3):97-239.
  5. Deyrup, M., and R. Franz (Eds.). 1994. Rare and Endangered Biota of Florida, Volume IV. Invertebrates. University Press of Florida, Gainesville, Florida. 798 pp.
  6. Florida Natural Areas Inventory (FNAI). 2023. Element Subnational Ranking Form in Biotics 5 database. NatureServe, Arlington, Virginia.
  7. Freshwater Mollusk Conservation Society (FMCS). 2023. The 2023 checklist of freshwater bivalves (Mollusca: Bivalvia: Unionida) of the United States and Canada. Considered and approved by the Bivalve Names Subcommittee October 2023. Online: https://molluskconservation.org/MServices_Names-Bivalves.html
  8. Frierson, L.S. 1927. A classified and annotated checklist of the North American naiades. Baylor University Press. Waco, Texas. 111 pp.
  9. Fritts, A.K., Fritts II, M.W., Peterson, D.L., Fox, D.A. and Bringolf, R.B., 2012. Critical linkage of imperiled species: Gulf Sturgeon as host for Purple Bankclimber mussels. <i>Freshwater Science</i>, <i>31</i>(4), pp.1223-1232.
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  22. O'Brien, C.A. and J.D. Williams. 2002. Reproductive biology of four freshwater mussels (Bivalvia: Unionidae) endemic to eastern gulf coastal plain drainages of Alabama, Florida, and Georgia. American Malacological Bulletin, 17(1/2): 147-158.
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  30. U.S. Fish and Wildlife Service (USFWS). 1999. Technical/agency draft recovery plan for endangered fat threeridge (<i>Amblema neislerii</i>), shinyrayed pocketbook (<i>Lampsilis subangulata</i>), gulf moccasinshell (<i>Medionidus penicillatus</i>), ochlockonee moccasinshell (<i>Medionidus penicillatus</i>), oval pigtoe (<i>Pleurobema pyriforme</i>), and purple bankclimber (<i>Elliptoideus sloatianus</i>) and threatened chipola slabshell (<i>Elliptio chipolaensis</i>), and purple bankclimber (<i>Elliptoideus sloatianus</i>). U.S. Fish and Wildlife Service: Atlanta, Georgia. 106 pp.
  31. U.S. Fish and Wildlife Service (USFWS). 2003. Recovery plan for endangered fat threeridge (<i>Amblema neislerii</i>), shinyrayed pocketbook <i>(Lampsilis subangulata</i>), gulf moccasinshell (<i>Medionidus penicillatus</i>), Ochlockonee moccasinshell (<i>Medionidus simpsonianus</i>), and oval pigtoe (<i>Pleurobema pyriforme</i>); and threatened chipola slapshell (<i>Elliptio chipolaensis</i>), and purple bankclimber (<i>Elliptoideus sloatianus</i>). U.S. Fish and Wildlife Service, Atlanta, Georgia. 142 pp.
  32. U.S. Fish and Wildlife Service (USFWS). 2006. Endangered and Threatened Wildlife and Plants; Critical Habitat for five endangered and two threatened mussels in four northeast Gulf of Mexico drainages; proposed rule. Federal Register, 71(108): 32746-32795.
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