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Threeridge

Amblema plicata

Summary 5

Amblema plicata, common name the Threeridge, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Unionidae, the river mussels.

Distribution 6

The three-ridge mussel occurs in the Mississippi, Gulf of Mexico and St. Lawrence drainages. In the Mississippi it is found from western New York to Minnesota and eastern Kansas. In the Gulf rivers it occurs from central Texas to the Yellow River of Florida. In the St. Lawrence it is absent from Lake Superior and its drainages. Its northern range includes the Red River of the North, Winnipeg River and Nelson River.

In Michigan this species is found mainly in rivers in the lower peninsula from the Saginaw and Grand drainages south. However, there are also records from the Sturgeon River in the upper peninsula.

Biogeographic Regions: nearctic (Native )

Habitat and ecology 7

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).


Systems
  • Freshwater

Iucn red list assessment 8


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

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.

Justification
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.

Morphology 9

The three-ridge is a thick shelled species up to 17.8 cm (7 inches) long, and rounded or quadrate. The anterior end is uniformly rounded, the posterior end truncated, rounded, truncated or bluntly pointed. The dorsal margin is long and straight and the ventral margin is slightly curved.

Umbos are low and slightly raised above the hinge line. Younger specimens will have a beak sculpture of three or four concentric double looped ridges.

The periostracum (outer shell layer) is brown and brownish-black in older individuals. The shell sculpture is distinct, with four to six prominent ridges parallel to the posterior ridge.

On the inner shell, the left valve has two pseudocardinal teeth, which are grooved, large, and triangular. The two lateral teeth are long, slightly curved, and serrated. The right valve has one stout, elevated, triangular and serrated. Anterior to this tooth is a smaller (lamellar) tooth. The one lateral tooth is high, slightly striated and curved.

The beak cavity is moderately deep. The nacre is white, and iridescent at the posterior end.

In Michigan, the three-ridge is fairly distinct and not easily confused with any other species.

Range length: 17.8 (high) cm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: sexes alike

Nature serve conservation status 10

Rounded Global Status Rank: G5 - Secure

Reasons: This species is considered common and widespread throughout much of the U.S. and Canada and is considered stable, or in some cases expanding, throughout its range.

Range description 11

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).

Sources and Credits

  1. (c) Wisconsin Department of Natural Resources, some rights reserved (CC BY-ND), https://www.flickr.com/photos/widnr/6511514061/
  2. (c) EOL Learning and Education Group, some rights reserved (CC BY), https://www.flickr.com/photos/44919417@N04/6810513508/
  3. (c) Sarah Robertson, some rights reserved (CC BY-NC), uploaded by Sarah Robertson
  4. (c) dbarclay, some rights reserved (CC BY-NC), uploaded by dbarclay
  5. Adapted by rkkessler from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Amblema_plicata
  6. Adapted by rkkessler from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31376220
  7. Adapted by rkkessler from a work by (c) International Union for Conservation of Nature and Natural Resources, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/34294074
  8. Adapted by rkkessler from a work by (c) International Union for Conservation of Nature and Natural Resources, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/34294071
  9. Adapted by rkkessler from a work by (c) The Regents of the University of Michigan and its licensors, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/31376222
  10. Adapted by rkkessler from a work by (c) NatureServe, some rights reserved (CC BY-NC), http://eol.org/data_objects/28949690
  11. (c) International Union for Conservation of Nature and Natural Resources, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/34294072

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