Ennucula granulosa (Verrill, 1884)

Notes on Nomenclature

To size: To 2.5mm. Shell Structure: Relatively solid. Equivalve: Equivalve. Equilateral: Inequilateral, the beaks lie approximately 30% of dorsal margin length from posterior. Tumidity: Relatively tumid. Outline: Broadly oval: height of shell approximately 85% of length; antero-dorsal margin rather short, curved and sloping with an angle at the junction with the anterior end; postero-dorsal margin slightly curved, steeply sloping with angled junction at posterior margin; anterior margin gently rounded with a slight angle at the junction with the ventral margin; posterior margins relatively straight, steeply sloping and with a distinct posterior-ventral junction; ventral margin deeply rounded; escutcheon indistinct, slightly raised, without defined edges; lunule lanceolate, not raised with poorly defined edges; umbo slightly swollen, rather broad and prominent. Contour: Slightly swollen umbonate.

Sculpture: Very fine concentric lines – appears almost smooth. Surface of shell also covered with dense, closely spaced, raised granules. Margin: Smooth. Ligament: Internal, opisthodetic, with a relatively large, rounded, triangular ligament seated in a well-developed resilifer. Hinge: Taxodont: Solid, continuous hinge plate, narrow below the beaks, broadening towards the anterior and posterior ends, with a well-developed, rounded resilifer which projects down from the hinge plate. Teeth robust, moderately long and blunt, usually 4-5 posterior and 6 anterior of the resilifer. Pallial Musculature: Pallial line indistinct, continuous with no pallial sinus. Adductor muscle scars; posterior oval, anterior elongate. Periostracum: Silky, grey green to olive; sometimes with deposits of hardened mud. Colour: White to bluey grey, slightly nacreous. Additional Characters: Series of coils on the right side of the body.

Distribution & Ecology

Northern part of Rockall Trough (~ 56°N, 09°W) in depths of 900-1300m. Also Bay of Biscay.
North American Basin (depth range 530-2178m) and Western European Basin.

Depth Range
Bathyal (500 - 2000m)

Additional Information & Related Species

Related Species

Nuculoidea : Nuculidae

Brevinucula verrilli

Ennucula corbuloides

Ennucula corticata

Ennucula granulosa

Ennucula tenuis

Nucula atacellana

Nucula hanleyi

Nucula nitidosa

Nucula nucleus

Nucula sulcata

Nucula tumidula

References

Listed are literature citing Ennucula granulosa (Verrill, 1884). 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.

Rhind P.M. & Allen J.A. 1992. Studies on the deep-sea Protobranchia (Bivalvia): the family Nuculidae. Bulletin of the British Museum of Natural History. 58 (1): 61-93.

Verrill 1884. Second Catalogue of Mollusca recently added to the fauna of the New England Coast and the adjacent parts of the Atlantic, consisting mostly of Deep Sea species, with notes on others previously recorded 6 . Transactions of the Connecticut Academy of Arts and Sciences. 139-294, pls. 28-32..

Verrill A E & Bush K J 1898. Revision of the deep water Mollusca of the Atlantic Coast of North America with descriptions of new genera and species Part 1 Bivalvia. Proceedings of the United States National Museum. 20: 775-901.

Resources

• Conchological Society of Great Britain & Ireland
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• CLEMAM
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• MarLIN
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• BivAToL
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