Species Account

Mytilopsis leucophaeta (Conrad, 1831)

Dreissenoidea : Dreissenidae

Tebble name: n/a
Smith & Heppell name: n/a

To size: Up to 4cm. Shell Structure: Thin but not fragile. Equivalve: Slightly inequivalve (RV slightly larger). Equilateral: Strongly inequilateral. Tumidity: Tumid. Outline: Mytiliform, narrow wedge-shaped.

Sculpture: Commarginal lines and growth stops. Margin: Inner margin smooth. Ligament: External, sunken. Hinge: Septum (shelf) with a triangular tooth arising from the inner dorsal edge. Pallial Musculature: Posterior adductor and pedal retractor scars coalesced as a long, crescent shape on posterior dorsal area. Pallial line slightly concave below the adductor scar. Periostracum: Thick with dense erect concentric laminae. Colour: Brown periostracum, white shell, tinged with purple.

Distribution & Ecology

Found in brackish waters such as lagoons, docks and estuaries. Uses a byssus to attach to hard substrates such as rocks, oysters, ropes and boats.

Native to the Gulf of Mexico it has spread in ballast water North to the Hudson River in New York state and south to Brazil. Distributed in Europe from Normandy to Denmark, Mediterranean, Black Sea and Caspian Sea.

Known from a few scattered locations in the UK: Roath Dock, Cardiff; Cliffe Fort Lagoon, Kent and Hubbert’s Bridge, Boston, Lincolnshire.

Depth Range

Additional Information & Related Species

Key Features & Similar Species

Distinguished from Dreissena polymorpha (zebra mussel) by presence of the tooth on septum. Small zebra mussels are more triangular-wedge shaped with a very long posterior dorsal margin. Whereas small Mytilopsis have a more streaam-lined, elongate profile. Mytilus edulis can be separated from Mytilus by its smooth periostracum and tan/blue coloured shell.

Related Species

Dreissenoidea : Dreissenidae


Listed are literature citing Mytilopsis leucophaeta (Conrad, 1831). Reference containing the species Type Description is highlighted.

Bamber R.N. & Taylor J.D. 2002. The brackish water mussel Mytilopsis leucophaeta (Conrad, 1831) (Bivalvia: Dreissenidae) in the river Thames. Journal of Conchology. 37 (4): 403-404.
Conrad T A 1831. Description of fifteen new species of Recent, and three of fossil shells, chiefly from the coast of the United States. Journal of the Academy of Natural Sciences of Philadelphia. 6: 256-268, pl 11.
Oliver P.G., Holmes A.M. & Mettam C. 1998. A species new to the British fauna. Journal of Conchology. 36 (2): 13-18.
Willing M.J. 2015. Two invasive bivalves, Rangia cuneata (GB Sowerby I, 1831) and Mytilopsis leucophaeta (Conrad, 1831), living in freshwater in Lincolnshire, Eastern England.. Journal of Conchology. 42 (2): 189-192.


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Record last modified: 13/05/2016