Species Account

Policordia densicostata (Locard, 1898)

Verticordioidea : Verticordiidae

Tebble name: n/a
Smith & Heppell name: Policordia densicostata (Locard, 1898)

To size: To 18mm. Shell Structure: Thin. Equivalve: Equivalve. Equilateral: Strongly inequilateral, beaks inturned and close to the anterior margin. Tumidity: Moderate. Outline: Rounded subquadrate, maximum dimension is from the beaks to the ventral margin; posterior dorsal margin long, forming a broad curve, posterior margin almost straight, as long or longer than post-dorsal margin; posterior ventral junction distinct, rounded; ventral margin curving to small rounded anterior margin. Contour: Concave depression below incurved beaks.

Sculpture: With increasing number of narrow radial raised lines, c. 35 at 5 mm to 50 at 10 mm; fine, dense, concentric striations between ribs. Margin: Inner margin smooth. Ligament: Internal with a lithodesma. Hinge: Teeth lacking. Pallial Musculature: Obscure. Periostracum: Thin, initially pale straw coloured, becoming darker, almost greenish in large specimens. Colour: Lustrous white.

Distribution & Ecology

Not recorded from British waters. Allen & Turner (1974) give range as off West Africa and the NW Atlantic; 1007-2325 m.

Depth Range
Bathyal (500 - 2000m)
Abyssal Rise (2000 - 4000m)

Additional Information & Related Species

Key Features & Similar Species

The Atlantic species of Policordia are difficult to identify on shell characters alone (see Allen & Turner, 1974). So far we have not seen enough material to add to Allen & Turner's comments. From the material that we have examined we are unable to be certain of the distinction between P. gemma and P. densicostata. Here we have included shells identified by others as P. gemma but we would probably have considered these to be the same as P. densicostata. P. densicostata was described from the Biscay region where most of our material has come from and therefore we would refer this material to this taxon. P. gemma has been identified from material collected further north and the shells have generally been much smaller rarely exceeding 5mm.

Additional Comments

See Policordia gemma

Related Species


Listed are literature citing Policordia densicostata (Locard, 1898). Reference containing the species Type Description is highlighted.

Locard A 1898. Expéditions scientifiques du Travailleur et du Talisman pendant les années 1880, 1881, 1882 et 1883. Mollusques testacés vol. 2. Paris, Masson. 517-1044, pls 23-40.


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Record last modified: 17/05/2016