Species Account

Bathyarca inaequisculpta (E A Smith, 1885)

Arcoidea : Arcidae

Tebble name: n/a
Smith & Heppell name: Bathyarca inaequisculpta (E A Smith, 1885)

To size: To 7mm. Shell Structure: Thin but not fragile, opaque. Equivalve: Inequivalve, left valve noticeably larger, right valve sitting inside left valve. Equilateral: Almost equilateral, beaks just in front of midline. Tumidity: Inflated. Outline: Subcircular (height = length), dorsal margin long, straight; umbos prominent; anterior, ventral and posterior margins forming a broad even curve; some with ventral slightly extended. Contour: Dorsal area narrow, flat; posterior angle indistinct.

Sculpture: Subcancellate, of numerous comarginal low ridges crossed by numerous radial raised lines; radial elements more prominent on the smaller right valve. Margin: Inner margin of larger left valve weakly crenulate adjacent to a submarginal groove; right valve smooth. Ligament: Duplivincular, chevrons developing from the posterior of the dorsal area. Hinge: Taxodont, teeth in two series set on a gently curved hinge plate, anterior set with up to 5 teeth, posterior set up to 5; posterior teeth subparallel to dorsal margin anterior teeth oblique. Pallial Musculature: Anterior adductor scar slightly smaller than posterior; smooth area below posterior scar indicates attachment of the expanded posterior mantle edge. Periostracum: Of fragile, pale straw coloured, very short bristles. Colour: white.

Distribution & Ecology

Semi-infaunal, attached by a few byssus threads in abyssal ooze. An abyssal species recorded widely in the Atlantic, including the Bay of Biscay, 3300-4700m.

Depth Range
Abyssal Rise (2000 - 4000m)
Abyssal Plain (4000m +)

Additional Information & Related Species

Key Features & Similar Species

The only Bathyarca that is subcircular and lacks a byssal notch or sulcus.

Related Species


Listed are literature citing Bathyarca inaequisculpta (E A Smith, 1885). Reference containing the species Type Description is highlighted.

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.
Oliver G & Allen J A 1980. The Functional and Adaptive Morphology of the Deep-Sea Species of the Arcacea (Mollusca: Bivalvia) from the Atlantic. Philosophical Transactions of the Royal Society of London Series B. 291: 45-76.
Smith E A 1885. Report on the Lamellibranchiata collected by HMS Challenger during the years 1873-1876. Reports of the scientific results of the voyage of HMS “Challenger”, Zoology. 13 (35): 1-341, 25pls.


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Record last modified: 17/05/2016