Utterbackia peninsularis - Bogan and Hoeh, 1995
Peninsular Floater
Taxonomic Status: Accepted
Related ITIS Name(s): Utterbackia peninsularis Bogan and Hoeh, 1995 (TSN 568434)
Unique Identifier: ELEMENT_GLOBAL.2.111921
Element Code: IMBIV55030
Informal Taxonomy: Animals, Invertebrates - Mollusks - Freshwater Mussels
Kingdom Phylum Class Order Family Genus
Animalia Mollusca Bivalvia Unionoida Unionidae Utterbackia
Check this box to expand all report sections:
Concept Reference
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.
Concept Reference Code: B98TUR01EHUS
Name Used in Concept Reference: Utterbackia peninsularis
Taxonomic Comments: Generic placement is based on the work of Hoeh (1990; 1991) and Hoeh et al. (1995). Electrophoretic evidence confirms that Utterbackia peggyae represents two species: Utterbackia peggyae and Utterbackia peninsularis (Bogan and Hoeh, 1994). Bogan and Hoeh (1995) split Utterbackia peninsularis from Utterbackia peggyae based on allozymes and stomach anatomy. This species was placed in the newly elevated genus Utterbackia by Hoeh (1990). Recently, Zanatta et al. (2007) supported the monophyly of both Pyganodon and Utterbackia using mutation coding of allozyme data, but also resolved the Eurasian Anodonta cygnea to Pyganodon, Utterbackia, and North American Anodonta; indicating futher phylogenetic analysis of the Anodontinae is required including both North American and Eurasian species.
Conservation Status

NatureServe Status

Global Status: G2G3
Global Status Last Reviewed: 15Jan2014
Global Status Last Changed: 05Oct2009
Rounded Global Status: G2 - Imperiled
Reasons: This species is restricted to northern and central peninsular Florida and is presumed to be stable throughout its range.
Nation: United States
National Status: N2N3 (05Oct2009)

U.S. & Canada State/Province Status
United States Florida (S2S3)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: 1000-20,000 square km (about 400-8000 square miles)
Range Extent Comments: Although formerly attributed to Utterbackia peggyae (Johnson, 1965; 1972), this species was subsequently recognized as distinct, with a distribution in peninsular Florida from the Suwannee River system (lower Suwanee and Santa Fe rivers) southward to the Hillsborough River system, Florida (Bogan and Hoeh, 1995).

Area of Occupancy: 501-12,500 4-km2 grid cells
Area of Occupancy Comments: Linear occupancy is 200-5000 km.

Number of Occurrences: 21 - 80
Number of Occurrences Comments: This species is restricted to northern and central peninsular Florida from the lower Suwannee and Santa Fe rivers southward to the Hillsborough River (Bogan and Hoeh, 1993).

Population Size: 100,000 to >1,000,000 individuals

Number of Occurrences with Good Viability/Integrity: Few to many (4-125)

Short-term Trend: Relatively Stable (<=10% change)
Short-term Trend Comments: Presumed stable

Long-term Trend: Decline of <30% to increase of 25%
Long-term Trend Comments: Presumed stable

Intrinsic Vulnerability: Moderately vulnerable to not intrinsically vulnerable.
Intrinsic Vulnerability Comments: Freshwater mussels are inherently vulnerable to threats from siltation, pollution, eutrophication, channelization, impoundment, collection, drought and water withdrawal, competiton from invasive non-native mussels, and changes to larval host fish populations.

Environmental Specificity: Moderate. Generalist or community with some key requirements scarce.
Environmental Specificity Comments: Presumption, need better data

Other NatureServe Conservation Status Information

Inventory Needs: Determine all sites of occurrence through comprehensive inventories.

Protection Needs: Maintain high water and benthic habitat (substrate) qualities, as well as adequate flow regimes, throughout all occupied river systems. This may be partially accomplished via establishment of buffers and streamside management zones for all agricultural, silvicultural, mining, and developmental activities; protection of floodplain forests and adjoining upland habitat is paramount. Best management practices to follow include employing forestry practices that cause minimal soil erosion; preventing access of livestock to natural surface waters and drains; situating roads at least 0.25 mi. (0.4 km) from heads of all tributaries, even more on steep slopes; using silt fencing and vegetation to control runoff and siltation at all stream crossings, especially during construction and maintenance; using and maintaining sewer systems rather than septic tanks and stream-dumping for management of wastewater; and avoiding use of agricultural pesticides on porous soils near streams. Prevent damming, dredging, and pollution throughout drainages, but especially near recorded sites. Remove existing dams, but with great care to limit downstream sedimentation. Limit withdrawal of surface and subterranean waters as necessary to maintain normal stream flows, especially during drought. Prevent or limit establishment of invasive species (including zebra mussel, Dreissena polymorpha) to the extent possible. Where appropriate, protect populations through acquisitions and easements over streamside lands by working with government agencies and conservation organizations.

Global Range: (1000-20,000 square km (about 400-8000 square miles)) Although formerly attributed to Utterbackia peggyae (Johnson, 1965; 1972), this species was subsequently recognized as distinct, with a distribution in peninsular Florida from the Suwannee River system (lower Suwanee and Santa Fe rivers) southward to the Hillsborough River system, Florida (Bogan and Hoeh, 1995).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States FL

Range Map
No map available.

U.S. Distribution by County Help
State County Name (FIPS Code)
FL Alachua (12001), Bradford (12007), Dixie (12029), Hillsborough (12057), Pasco (12101), Polk (12105), Union (12125)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
03 Oklawaha (03080102), Hillsborough (03100205)+, Tampa Bay (03100206), Withlacoochee (03100208)+, Lower Suwannee (03110205)+, Santa Fe (03110206)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
U.S. Distribution by Watershed (based on multiple information sources) Help
Ecology & Life History
Basic Description: a freshwater mussel
General Description: See Bogan and Hoeh (1993).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Riverine Habitat(s): CREEK, Low gradient, MEDIUM RIVER, Moderate gradient, Pool
Special Habitat Factors: Benthic
Habitat Comments: Found in canals, creeks, and rivers with sand and/or muddy substrates with slight to moderate current (Bogan and Hoeh 1993).
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
Group Name: Freshwater Mussels

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens, including live specimens or recently dead shells (i.e., soft tissue still attached and/or nacre still glossy and iridescent without signs of external weathering or staining), at a given location with potentially recurring existence. Weathered shells constitute a historic occurrence. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information.
Mapping Guidance: Based on the separation distances outlined herein, for freshwater mussels in STANDING WATER (or backwater areas of flowing water such as oxbows and sloughs), all standing water bodies with either (1) greater than 2 km linear distance of unsuitable habitat between (i.e. lotic connections), or (2) more than 10 km of apparently unoccupied though suitable habitat (including lentic shoreline, linear distance across water bodies, and lentic water bodies with proper lotic connections), are considered separate element occurrences. Only the largest standing water bodies (with 20 km linear shoreline or greater) may have greater than one element occurrence within each. Multiple collection or observation locations in one lake, for example, would only constitute multiple occurrences in the largest lakes, and only then if there was some likelihood that unsurveyed areas between collections did not contain the element.

For freshwater mussels in FLOWING WATER conditions, occurrences are separated by a distance of more than 2 stream km of unsuitable habitat, or a distance of more than 10 stream km of apparently unoccupied though suitable habitat. Standing water between occurrences is considered suitable habitat when calculating separation distance for flowing water mussel species unless dispersal barriers (see Separation Barriers) are in place.

Several mussel species in North America occur in both standing and flowing water (see Specs Notes). Calculation of separation distance and determination of separation barriers for these taxa should take into account the environment in which the element was collected. Juvenile mussels do not follow this pattern and juveniles are typically missed by most standard sampling methods (Hastie and Cosgrove, 2002; Neves and Widlak, 1987), therefore juvenile movement is not considered when calculating separation distance.

Separation Barriers: Separation barriers within standing water bodies are based solely on separation distance (see Separation Distance-suitable, below). Separation barriers between standing water bodies and within flowing water systems include lack of lotic connections, natural barriers such as upland habitat, absence of appropriate species specific fish hosts, water depth greater than 10 meters (Cvancara, 1972; Moyle and Bacon, 1969) or anthropogenic barriers to water flow such as dams or other impoundments and high waterfalls.
Separation Distance for Unsuitable Habitat: 2 km
Separation Distance for Suitable Habitat: 10 km
Alternate Separation Procedure: None
Separation Justification: Adult freshwater mussels are largely sedentary spending their entire lives very near to the place where they first successfully settled (Coker et al., 1921; Watters, 1992). Strayer (1999) demonstrated in field trials that mussels in streams occur chiefly in flow refuges, or relatively stable areas that displayed little movement of particles during flood events. Flow refuges conceivably allow relatively immobile mussels to remain in the same general location throughout their entire lives. Movement occurs with the impetus of some stimulus (nearby water disturbance, physical removal from the water such as during collection, exposure conditions during low water, seasonal temperature change or associated diurnal cycles) and during spawning. Movement is confined to either vertical movement burrowing deeper into sediments though rarely completely beneath the surface, or horizontal movement in a distinct path often away from the area of stimulus. Vertical movement is generally seasonal with rapid descent into the sediment in autumn and gradual reappearance at the surface during spring (Amyot and Downing, 1991; 1997). Horizontal movement is generally on the order of a few meters at most and is associated with day length and during times of spawning (Amyot and Downing, 1997). Such locomotion plays little, if any, part in the distribution of freshwater mussels as these limited movements are not dispersal mechanisms. Dispersal patterns are largely speculative but have been attributed to stream size and surface geology (Strayer, 1983; Strayer and Ralley, 1993; van der Schalie, 1938), utilization of flow refuges during flood stages (Strayer, 1999), and patterns of host fish distribution during spawning periods (Haag and Warren, 1998; Watters, 1992). Lee and DeAngelis (1997) modeled the dispersal of freshwater into unoccupied habitats as a traveling wave front with a velocity ranging from 0.87 to 2.47 km/year (depending on mussel life span) with increase in glochidial attachment rate to fish having no effect on wave velocity.

Nearly all mussels require a host or hosts during the parasitic larval portion of their life cycle. Hosts are usually fish, but a few exceptional species utilize amphibians as hosts (Van Snik Gray et al., 2002; Howard, 1915) or may metamorphose without a host (Allen, 1924; Barfield et al., 1998; Lefevre and Curtis, 1911; 1912). Haag and Warren (1998) found that densities of host generalist mussels (using a variety of hosts from many different families) and displaying host specialists (using a small number of hosts usually in the same family but mussel females have behavioral modifications to attract hosts to the gravid female) were independent of the densities of their hosts. Densities of non-displaying host specialist mussels (using a small number of hosts usually in the same family but without host-attracting behavior) were correlated positively with densities of their hosts. Upstream dispersal of host fish for non-displaying host specialist mussels could, theoretically, transport mussel larvae (glochidia) over long distances through unsuitable habitat, but it is unlikely that this occurs very often. D. Strayer (personal communication) suggested a distance of at least 10 km, but a greater distance between occurrences may be necessary to constitute genetic separation of populations. As such, separation distance is based on a set, though arbitrary, distance between two known points of occurrence.

Date: 18Oct2004
Author: Cordeiro, J.
Notes: Contact Jay Cordeiro (jay_cordeiro@natureserve.org) for a complete list of freshwater mussel taxa sorted by flow regime.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 15Jan2014
NatureServe Conservation Status Factors Author: Jackson, D. R. (2014); Cordeiro, J. (2007); Morrison, M. (1998)
Element Ecology & Life History Edition Date: 11Dec2007
Element Ecology & Life History Author(s): Cordeiro, J.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

  • Bogan, A.E. and W.R. Hoeh. 1995. Utterbackia peninsularis, a newly recognized freshwater mussel (Bivalvia: Unionidae: Anodontinae) from Peninsular Florida, U.S.A. Walkerana, 7(17/18): 275-287.

  • Hoeh, W.R. 1990. Phylogenetic relationships among eastern North American Anodonta (Bivalvia: Unionidae). Malacological Review, 23: 63-82.

  • Hoeh, W.R. 1991. The evolution and consequences of simultaneous hermaphroditism in the freshwater mussel genus Utterbackia (Bivalvia: Unionidae). Ph.D. Dissertation, Biology, University of Michigan, Ann Arbor, Michigan. 97 pp.

  • Hoeh, W.R., K.S. Frazer, E. Naranjo-Garcia, and R.J. Trdan. 1995. A phylogenetic perspective on the evolution of simultaneous hermaphorditism in a freshwater mussel clade (Bivalvia: Unionidae: Utterbackia). Malacological Review, 28: 25-42.

  • Howard, A.D. 1915. Some exceptional cases of breeding among the Unionidae. The Nautilus 29:4-11.

  • Johnson, R.I. 1965. A hithero overlooked Anodonta (Mollusca: Unionidae) from the Gulf drainage of Florida. Breviora, 213: 1-7.

  • Johnson, R.I. 1972a. The Unionidae (Mollusca: Bivalvia) of peninsular Florida. Bulletin of the Florida State Museum of Biological Science 16(4): 181-249.

  • Lefevre, G. and W.T. Curtis. 1912. Studies on the reproduction and artificial propogation of fresh-water mussels. Bulletin of the Bureau of Fisheries 30:102-201.

  • Moyle, P. and J. Bacon. 1969. Distribution and abundance of molluscs in a fresh water environment. Journal of the Minnesota Academy of Science 35(2/3):82-85.

  • Strayer, D. 1983. The effects of surface geology and stream size on freshwater mussel (Bivalvia, Unionidae) distribution in southeastern Michigan, U.S.A. Freshwater Biology 13:253-264.

  • Strayer, D.L. 1999a. Use of flow refuges by unionid mussels in rivers. Journal of the North American Benthological Society 18(4):468-476.

  • Strayer, D.L. and J. Ralley. 1993. Microhabitat use by an assemblage of stream-dwelling unionaceans (Bivalvia) including two rare species of Alasmidonta. Journal of the North American Benthological Society 12(3):247-258.

  • 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.

  • Van der Schalie, H. 1938a. The naiad fauna of the Huron River in southeastern Michigan. Miscellaneous Publication of the Museum of Zoology, University of Michigan 40:7-78.

  • Watters, G.T. 1992a. Unionids, fishes, and the species-area curve. Journal of Biogeography 19:481-490.

  • Williams, J. D., R. S. Butler, G. L. Warren, and N. A. Johnson.  2014a.  Freshwater Mussels of Florida.  University of Alabama Press, Tuscaloosa, Alabama. 498 pp.

  • Zanatta, D.T., A. Ngo, and J. Lindell. 2007a. Reassessment of the phylogenetic relationships among Anodonta, Pyganodon, and Utterbackia (Bivalvia: Unionoida) using mutation coding of allozyme data. Proceedings of the Academy of Natural Sciences of Philadelphia 156: 211-216.

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