Species Account

Nucula tumidula Malm, 1861

Nuculoidea : Nuculidae

Tebble name: n/a
Smith & Heppell name: Nucula tumidula (Malm, 1860)

To size: To 7 mm. Shell Structure: Solid. Equivalve: Equivalve. Equilateral: Inequilateral, the beaks lie approximately 25-30% of dorsal margin length from posterior. Tumidity: Moderately tumid. Outline: Rounded triangular: height of shell approximately 85% of length; antero-dorsal margin long, curved and sloping with an angle at the junction with the anterior end; postero-dorsal margin slightly straight, steeply sloping with angled junction at posterior margin; anterior and posterior margins narrowly rounded; ventral margin more deeply rounded; escutcheon heart-shaped, slightly projecting, with poorly defined edges; lunule lanceolate, not raised with poorly defined edges; umbo rather flattened, not prominent.

Sculpture: Very finely decussate, sculpture of well defined, closely, but irregularly spaced, raised concentric lines which increase in prominence towards the outer margin, and numerous, very fine closely-spaced, radial riblets. Margin: Inner margin crenulate in correspondence to riblets. Ligament: Internal, opisthodetic, rounded triangular ligament seated in a well-developed resilifer. A thin, barely visible, external ligament lies anterior to the beaks. Hinge: Taxodont: Broad and continuous hinge plate with a well-developed triangular shaped resilifer. Teeth long and pointed, usually 5-7 posterior and 11-14 anterior. The teeth extend across the top of the resilifer. Pallial Musculature: Pallial line continuous with no pallial sinus. Periostracum: Slightly glossy, grey green to olive; periostracum and shell often eroded at the umbo. Colour: White. Inside of shell nacreous.

Distribution & Ecology

Widely distributed in the Eastern Atlantic primarily at bathyal depths. In study area known only from the slope off northern Scotland and Shetland.

Depth Range
Bathyal (500 - 2000m)

Additional Information & Related Species


Listed are literature citing Nucula tumidula Malm, 1861. Reference containing the species Type Description is highlighted.

Malm A W 1861. Raekke af fiske, krebsdjur og bloddjur, som ere nye for den Skandinaviske fauna. Skandinaviske Naturforskeres 8de møde i Kjøbenhavn 1860, Forhandlingar. 1860: 616-624.
Salas C. 1996. Marine Bivalves from off the Southern Iberian Peninsula collected by the Balgim and Fauna 1 expeditions. Haliotis. 25: 33-100.


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Record last modified: 17/05/2016