Douglas Mason, USA
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Geukensia demissa (Dillwyn, 1817)
Geukensia demissa is a mussel from the mussel family (Mytilidae). Originally native to the east coast of North America, it has since been introduced to the west coast of North America. The ribbed mussel is the type species of the genus Geukensia Van den Poel, 1959.
The mussel grows up to 13 cm, but usually stays a little smaller at 10 cm. The posterior part of the shell in particular is covered with dense, radial ribs, to which the colloquial name "Ribbed Mussel" refers. The periostracum is olive-brown, yellowish-brown, dark brown or black. The mussel shell is off-white and can only be seen where the periostracum has been rubbed off. The inside is silver or bluish white and mostly iridescent.
There is a possibility of confusion with Geukensia demissa of the mussel Geukensia granosissima, but it has a fewer ribs that are further apart. Also, in Geukensia granosissima, the species name "granosissima" refers to the granulation of the ribs. Geukensia demissa lacks granulation and has smooth ribs.
Geukensia demissa lives partially buried in the muddy intertidal area, attached with their byssus threads. The mussel is said to be up to 20 years old.
Synonymised names:
Brachidontes demissus (Dillwyn, 1817) · unaccepted
Brachydontes clava Mörch, 1853 · unaccepted
Modiola plicatula Lamarck, 1819 · unaccepted (junior synonym)
Modiola semicostata Conrad, 1837 · unaccepted
Modiolus demissus (Dillwyn, 1817) · unaccepted (unaccepted combination)
Modiolus demissus var. plicatula Lamarck, 1819 · unaccepted (junior synonym)
Mytilus demissus Dillwyn, 1817 · unaccepted
Volsella demissa (Dillwyn, 1817) · unaccepted
Geukensia demissa is a mussel from the mussel family (Mytilidae). Originally native to the east coast of North America, it has since been introduced to the west coast of North America. The ribbed mussel is the type species of the genus Geukensia Van den Poel, 1959.
The mussel grows up to 13 cm, but usually stays a little smaller at 10 cm. The posterior part of the shell in particular is covered with dense, radial ribs, to which the colloquial name "Ribbed Mussel" refers. The periostracum is olive-brown, yellowish-brown, dark brown or black. The mussel shell is off-white and can only be seen where the periostracum has been rubbed off. The inside is silver or bluish white and mostly iridescent.
There is a possibility of confusion with Geukensia demissa of the mussel Geukensia granosissima, but it has a fewer ribs that are further apart. Also, in Geukensia granosissima, the species name "granosissima" refers to the granulation of the ribs. Geukensia demissa lacks granulation and has smooth ribs.
Geukensia demissa lives partially buried in the muddy intertidal area, attached with their byssus threads. The mussel is said to be up to 20 years old.
Synonymised names:
Brachidontes demissus (Dillwyn, 1817) · unaccepted
Brachydontes clava Mörch, 1853 · unaccepted
Modiola plicatula Lamarck, 1819 · unaccepted (junior synonym)
Modiola semicostata Conrad, 1837 · unaccepted
Modiolus demissus (Dillwyn, 1817) · unaccepted (unaccepted combination)
Modiolus demissus var. plicatula Lamarck, 1819 · unaccepted (junior synonym)
Mytilus demissus Dillwyn, 1817 · unaccepted
Volsella demissa (Dillwyn, 1817) · unaccepted
