Species Account

Portlandia intermedia (M.Sars, 1865)

Nuculanoidea : Nuculanidae

Tebble name:
Smith & Heppell name: Yoldiella intermedia (M Sars, 1858)

Notes on Nomenclature

Nuculanidae in place of Yoldiidae
Killeen & Turner (2009) use Nuculanidae instead of Yoldiidae in agreement with Ockelmann & Warén (1998) who explan that the distinguishing characters between these two families has never been well documented. Until the Yoldiidae can be clearly distinguished from the Nuculanidae we shall treat them under the single family Nuculanidae.

To size: To 13mm. Shell Structure: Solid, but not robust. Equivalve: Equivalve. Equilateral: Moderately inequilateral, the beaks lie at least 40% of dorsal margin length from anterior. Becomes more inequilateral with growth. Tumidity: Moderately inflated. Outline: Elongate-oval: antero-dorsal margin short, slightly curved; postero-dorsal margin long, almost horizontal with a dorsal margin – posterior margin junction; lower posterior margin obliquely truncated; to a lesser extent the upper posterior margin may also be obliquely truncated, creating a pointed or weakly rostrate posterior margin; anterior margin rounded; ventral margin shallowly curved. Dorsal margin crimped either side of the umbo. Elongate lunule and escutcheon. Umbo broad, swollen and prominent above the dorsal margin, well to the anterior of midline.

Sculpture: Virtually lacking sculpture, with only faint concentric lines and growth stops. Margin: Smooth. Ligament: Amphidetic, with the ligament seated in a well developed, projecting chondrophore. Hinge: Taxodont: Hinge plate continuous, relatively narrow with 5-6 blunt, chevron-shaped teeth on either side of the ligament. Periostracum: Glossy, dark straw-coloured with darker bands at growth stops. Colour: White. Additional Characters: The hind-gut forms a simple, rounded loop on the right side of the body.

Distribution & Ecology

Not known living in this area. Only dead and fossil shells recorded around Shetland in depths from 420 to 1150m.
Arctic, circumpolar species, living mostly in depths of 20-300m. Richling (2000) gives a depth range of 7-520m.

Depth Range
Continental Shelf (to 200m)
Continental Margin Zone (200 - 500m)

Additional Information & Related Species


Listed are literature citing Portlandia intermedia (M.Sars, 1865). Reference containing the species Type Description is highlighted.

Killeen I.J. & Turner J. 2009. Yoldiella and Portlandia (Bivalvia) from the Faroe-Shetland Channel and Rockall Trough, Northeast Atlantic. Journal of Conchology. 39 (6): 733-778.
Sars M 1865. Malacozoologiske lagttagelser. Forhandlinger i Videnskabsselskabet i Kristiania. 1864: 283-315.
Warén A 1989. Taxonomic comments on some protobranch bivalves from the northeastern Atlantic. Sarsia. 74: 223-259.


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Record last modified: 22/03/2016