Amblema plicata 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Bivalvia Unionoida Unionidae

Scientific Name: Amblema plicata (Say, 1817)
Common Name(s):
English Threeridge
Unio plicata Say, 1817

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-03-05
Assessor(s): Cordeiro, J. & Bogan, A.
Reviewer(s): Bohm, M., Collen, B. & Seddon, M.
Contributor(s): Richman, N., Duncan, C., Offord, S., Dyer, E., Soulsby, A.-M., Whitton, F., Kasthala, G., McGuinness, S., Milligan, HT, De Silva, R., Herdson, R., Thorley, J., McMillan, K. & Collins, A.
Amblema plicata has been assessed as Least Concern, due to the fact that it has a broad distribution in North America and is widespread and abundant throughout its range. It is also considered to be stable and in some cases expanding throughout its range.

Geographic Range [top]

Range Description:

This species is endemic to North America. It is distributed from the coastal plain portion of the Gulf of Mexico drainages from the Escambia River in Florida west to Texas and north into the Mississippi River drainage (Mulvey et al. 1997). It is also known from the St. Lawrence River drainage, but it is absent from Lake Superior and its drainages (Burch 1975). Butler (1989) lists the distribution as throughout the Interior Basin and from the San Antonio River, Texas, east to the Choctawhatchee River, but it is not known from the Yellow River. In Michigan the species is found mainly in rivers in the lower peninsula from the Saginaw and Grand River drainages to the south. However, there are some records from the Sturgeon River in the upper peninsula (Burch 1975). In Canada, the species’ range is restricted to southern Ontario, southern Manitoba and southeastern Saskatchewan. It is widely distributed and often abundant in Canada. It is restricted to the Lake Erie drainage in Ontario (Metcalfe-Smith and Cadmore-Vokey 2004). Its northern range includes the Red River of the North, Winnipeg River and Nelson River (Burch 1975). It extends into the Niagara River drainage in western New York State (Strayer and Jirka 1997). 

Countries occurrence:
Canada (Manitoba, Ontario, Saskatchewan); United States (Alabama, Arkansas, Florida, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New York, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Virginia, West Virginia, Wisconsin)
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]


In Canada, the species is often abundant (Metcalfe-Smith and Cadmore-Vokey 2004). In the United States, the species is widespread and common throughout most of its range but is apparently declining in some smaller streams (Illinois Natural History Survey 2009). Overall, it is considered to be stable, and in some cases expanding, throughout its range (NatureServe 2009).

Current Population Trend:Stable
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:

This species is a generalist and is known from a variety of habitats, ranging from small streams to big rivers, as well as lakes. It is known to occur in habitats with little or no current, and also from habitats where there is a very fast current. It is also known to occur on a variety of substrates, including clay, mud, sand and gravel. It is however most common on substrates composed of sand and gravel at depths of one to three feet, though it has been found at depths of up to 30 feet (Parmalee and Bogan 1998).

The age of sexual maturity for this species is not known. It is, as a unionid, gonochoristic and viviparous. The glochidia (larval stage) are released as live offspring from the female after they are fully developed. The species is a short-term brooder and breeds once annually in the spring. In the Huron River, the species is gravid from early June to mid-July and it probably spawns in May (Lefevre and Curtis 1912, van der Schalie 1938, Watters 1995).


Use and Trade [top]

Use and Trade:

The species is harvested for use by the pearl industry due to its sturdy shell. The shell of the species is sliced and ground into beads (“slugs”) which are then placed in pearl-producing oysters in order for them to create a large pearl over the basis of the freshwater mussel shell (Oesch 1984, Watters 1995).

Threats [top]

Major Threat(s):

The species is harvested and utilised by the pearl industry (Oesch 1984, Watters 1995), but other threats to the species throughout its range are not known. It is considered stable throughout its range and is therefore unlikely to be significantly affected by any major threats.

Conservation Actions [top]

Conservation Actions:

The species has been given a NatureServe Global Heritage ranking of G5 – Secure (NatureServe 2009). There are no species-specific conservation measures in place for this species.

Citation: Cordeiro, J. & Bogan, A. 2012. Amblema plicata. The IUCN Red List of Threatened Species 2012: e.T203724A2770567. . Downloaded on 16 July 2018.
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