Musculus costulatus (Risso, 1826)
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, rather narrow; ligament margin long, not sloping steeply and continuously curving with posterior dorsal margin; posterior narrowly rounded; ventral margin long, more or less straight but often depressed adjacent to non ribbed area; anterior narrow, rounded protruding slightly.
Sculpture: Radially ribbed except for smooth median area; 20-30 flat posterior ribs, interspaces about 1/2 width of ribs; 8-10 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 contiguous with marginal crenulations, otherwise smooth. Pallial Musculature: Mostly obscure. Periostracum: Thin persistent. Colour: A combination of periostracal and shell colouration renders fresh shells an overall rather vivid green with brown to brown black maculations these most bold over the dorsal area.Internally lustrous with brown colouration showing through.
Distribution & Ecology
Continental Shelf (to 200m)
Additional Information & Related Species
Mytiloidea : Mytilidae
Listed are literature citing Musculus costulatus (Risso, 1826). Reference containing the species Type Description is highlighted.
Risso A 1826. Histoire naturelle des principales productions de l'Europe Méridionale et particulièrement de celles des environs de Nice et des Alpes Maritimes 1. Paris, Levrault. 448pp.
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