Musculus discors (Linnaeus, 1767)Mytiloidea : Mytilidae
To size: To 12mm. Shell Structure: Thin but not fragile. Equivalve: Equivalve. Equilateral: Strongly inequilateral beaks close to the anterior margin. Tumidity: Not inflated, umbos low. Outline: Modioliform; ligament margin long, not sloping steeply, angled to posterior dorsal margin; posterior rounded; ventral margin long, more or less straight but often depressed adjacent to non ribbed area; anterior narrow, rounded.
Sculpture: Radially ribbed except for smooth median area; 30-40 flat posterior ribs often faint, interspaces narrow; 9-12 prominent anterior ribs; Overall with comarginal lines and growth stops. Margin: Crenulate where radial ribs meet margin. Ligament: Deeply inset extending for most of the posterior dorsal margin. Hinge: Hinge plate narrow, few large dysodont teeth posterior of ligament distinct from marginal crenulations, otherwise smooth. Pallial Musculature: Mostly obscure. Periostracum: Green to greenish brown, thin, persistent. Colour: Grayish white, internally lustrous.
Distribution & Ecology
Lower intertidal and shallow sublittoral attached to rocks and algae, occasionally forming dense rafts on stable gravel bottoms.
Continental Shelf (to 200m)
Juveniles & Similar Species
Key Features & Similar Species
Listed are literature citing Musculus discors (Linnaeus, 1767). Reference containing the species Type Description is highlighted.
Linnaeus C 1767. Systema Naturae. Editio duodecima. 1. Regnum Animale. 1&2 Homliae, Laurentii Salvii. 1-532: 533-1327.
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