Species Account

Dacrydium ockelmanni Mattson & Warén, 1977

Mytiloidea : Mytilidae

Tebble name: n/a
Smith & Heppell name: Dacrydium ockelmanni Mattson & Warén, 1977

To size: Very small to 4mm. Shell Structure: Fragile, hyaline. Equivalve: Equivalve. Equilateral: Inequilateral beaks close to anterior margin. Tumidity: Compressed. Outline: Outline modioliform, beaks subterminal; ventral margin long more or less straight; dorsal margins almost straight, anterior dorsal very short, anterior narrowly rounded and pronounced, posterior dorsal long sloping steeply relative to ventral margin; posterior and posterior ventral margins forming a smooth broad curve. Contour: Prodissoconch small about 140μm in diameter.

Sculpture: Sculpture smooth except for scattered weak growth lines. Margin: Inner margin smooth. Ligament: Ligament small, internal, situated in a distinct sunken resilifer beneath the beaks. Hinge: Hinge plate narrow, ligament margin with up to 50 small dysodont teeth, these decreasing in size towards the beaks; a few small teeth are also present anterior of the beaks. Pallial Musculature: Anterior adductor scar about 1/2 size of posterior. Periostracum: Transparent. Colour: White, glassy.

Distribution & Ecology

Along the Atlantic Margin this species is typically found on the upper slope but has a shallower range further north and a deeper range further south

Depth Range
Continental Margin Zone (200 - 500m)
Bathyal (500 - 2000m)

Additional Information & Related Species

Key Features & Similar Species

The very steep angle of the dorsal margin relative to the ventral margin is characteristic, this angle being much less in D. vitreum. The teeth along the ligament margin are fine and simple unlike the irregular bar shaped teeth in D. vitreum.

Related Species


Listed are literature citing Dacrydium ockelmanni Mattson & Warén, 1977. Reference containing the species Type Description is highlighted.

Mattson S & Warén A 1877. Dacrydium ockelmanni sp. n. (Bivalvia: Mytilidae) in Western Norway. Sarsia. 63: 1-6.
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.
Salas C & Gofas S 1997. Brooding and non-brooding Dacrydium (Bivalvia: Mytilidae): a review of the Atlantic species. Journal of Molluscan Studies. 63: 261-283.
Warén A 1991. New and little known Mollusca from Iceland and Scandinavia. Sarsia. 76: 53-124.


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Record last modified: 22/03/2016