Species Account

Cuspidaria obesa (Lovén, 1846)

Verticordioidea : Cuspidariidae

Tebble name: n/a
Smith & Heppell name: Cuspidaria obesa (Lovén, 1846)

To size: To 12mm. Shell Structure: Thin but robust. Equivalve: Slightly inequivalve LV overlapping RV ventrally. Equilateral: Equilateral, beaks close to midline. Tumidity: Moderately inflated. Outline: Body of shell subovate, rather deep; dorsal anterior area small; anterior broadly rounded and continuous with broadly curved ventral margin. Umbos relatively low. Rostrum relatively long, dorsal margin straight and gently sloping or slightly curved, ventral margin concave corresponding to shallow sulcus between body and rostrum.

Sculpture: Of fine concentric lines and growth stops, those more coarse over rostrum. Margin: Inner margin smooth. Ligament: Internal, small beneath beaks. Hinge: RV with a prominent posterior lateral flange. Pallial Musculature: Obscure. Periostracum: Thin, lamellar over rostrum, brownish in colour. Colour: Shell white.

Distribution & Ecology

A subarctic and north boreal species commonly found at shelf depths off northern Norway, Iceland, Greenland. Both Allen & Morgan (1981) and Olabarria (2005) record it from bathyal and abyssal depths in the Bay of Biscay. We are uncertain of its occurrence in the northern North Sea and along the Atlantic margin from where it has been recorded down to depths of 4900m. The enormous bathymetric range attributed to this species suggests that there is more than one species involved.

Depth Range
Continental Shelf (to 200m)
Continental Margin Zone (200 - 500m)
Bathyal (500 - 2000m)
Abyssal Rise (2000 - 4000m)
Abyssal Plain (4000m +)

Additional Information & Related Species

Key Features & Similar Species

In British waters, if this species does occur here, it will be confused with small specimens of C. cuspidata in which the anterior is rounded and not sloping steeply. In large shells of C. cuspidata the anterior slopes steeply and is almost straight. If C. obesa does occur in bathyal depth then small specimens are similar to C. parva in outline but lack the microscopic punctae. Can also be confused with C. subtorta but that shell is very tumid and the rostrum proportionately shorter.

Related Species


Listed are literature citing Cuspidaria obesa (Lovén, 1846). Reference containing the species Type Description is highlighted.

Allen J A & Morgan R E 1981. The functional morphology of Atlantic deep water species of the families Cuspidariidae and Poromyidae (Bivalvia): an analysis of the evolution of the septibranch condition. Philosophical Transactions of the Royal Society of London Series B. 294: 413-546.
Lovén S 1846. Index Molluscorum litora Scandinaviae occidentalia habitantium Öfversigt af Kongliga Vetenskaps Akademiens Förhandlingar. 134-160, 182-204.
Olabarria C. 2005. Patterns of bathymetric zonation of bivalves in the Porcupine Sea Bight and adjacent abyssal plain, NE Atlantic. Deep-Sea Research I. 52: 15-31.


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Record last modified: 22/03/2016