Bentharca asperula (Dall 1881)Arcoidea : Arcidae
Inequilateral, beaks at about 1/4 length of dorsal margin from anterior.
Trapezoidal – wedge shaped, posterior greatly expanded, umbos low; dorsal margin long, straight; posterior margin broadly rounded; ventral and anterior margins continuous gently curved with a prominent byssus indentation; anterior roundly pointed.
Posterior angle indistinct; median area with byssal sinus; dorsal area narrow, flat.
Sculpture: Weak, primarily of well spaced, comarginal, low ridges these cut by radial rows of bristle insertion marks. Margin: Inner margin smooth. Ligament: Duplivincular, v-shaped ligament bands arising from posterior of dorsal area at first, then between beaks. Hinge: Taxodont, teeth very small, in two series separated by an edentulous space, set on a narrow straight hinge plate; up to 5 anterior and 6 posterior teeth; anterior set angled obliquely, posterior set subparallel to dorsal margin. Pallial Musculature: Adductor scars unequal, anterior is smaller than posterior. Periostracum: Of brown to dark brown bristles over the posterior area, as frills on median and anterior. Colour: White.
Distribution & Ecology
Attached by a thin byssus to small stones, gravel and often the shells of Limopsis tenella. At the abyssal rise and abyssal depths, generally greater than 2000m. Rare in Rockall Trough, more frequent in Biscay basin.
Bathyal (500 - 2000m)
Abyssal Rise (2000 - 4000m)
Abyssal Plain (4000m +)
Juveniles & Similar Species
Key Features & Similar Species
Wedge shape and co-marginal sculpture is unlike all other deep water arcids.
Listed are literature citing Bentharca asperula (Dall 1881). Reference containing the species Type Description is highlighted.
Dall W H 1881. Reports on the results of dredging, under the supervision of Alexander Agassiz, in the Gulf of Mexico and in the Caribbean Sea, 1877-79, by the U.S. Coast Survey Steamer “Blake”. XV, Preliminary report on the Mollusca. Bulletin of the Museum of Comparative Zoology, Harvard. 9: 33-144.
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.
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