Yoldiella nana (M Sars, 1865)
Nuculanoidea : Nuculanidae
To size: To 3mm. Shell Structure: Thin, but not fragile. Equivalve: Equivalve. Equilateral: Equilateral. Tumidity: Moderately tumid. Outline: Ovate: antero- and postero-dorsal margins short, almost horizontal and slightly convex; anterior margin narrowly rounded, upper part very slightly obliquely truncated; lower posterior margin obliquely truncated; ventral margin shallowly rounded. Umbo central, moderately broad, prominent, projecting above the dorsal margin.
Sculpture: Virtually smooth with only very faint, closely spaced concentric lines and growth rings in larger specimens. Margin: Smooth. Ligament: Amphidetic, attached internally to the underside of the beak without a projecting chondrophore or resilifer. Moderately short and thin. Hinge: Taxodont: Hinge plate moderately broad (broadening rapidly away from the ligament) with 5-6 blunt, chevron-shaped teeth on either side of the umbo. Periostracum: Silky to slightly glossy, straw-coloured. Colour: Translucent white. Additional Characters: The hind-gut forms a simple, rounded loop on the right side of the body.
Distribution & Ecology
Found over a large area of the North Atlantic from Martha’s Vineyard in the west, to Lofoten, northern Iceland and the entire Norwegian coast in the east and south to include the Mediterranean. Around the Faroes at depths from 170-1200m (Sneli et al. 2005). Also recorded from the Laptev Sea, Siberia in depths of 96-670m.
Continental Shelf (to 200m)
Continental Margin Zone (200 - 500m)
Bathyal (500 - 2000m)
Additional Information & Related Species
Yoldiella nana form A is much more tumid than the typical form of Y. nana, and the shell is slightly more solid. The umbo is broader and more prominent in relation to the size of the shell. This form is also more angular at the postero-dorsal and antero-dorsal regions. The ventral margin is shallowly rounded as found in the typical Y. nana.
Yoldiella nana form B is also more tumid than the typical form of Y. nana, and the shell is slightly more solid. The umbo is broader and more prominent in relation to the size of the shell. The postero-dorsal and antero-dorsal regions more closely resemble that of typical Y. nana, but the ventral margin is much more strongly rounded and is more similar to ventral margin found in Y. solidula.
Nuculanoidea : Nuculanidae
Listed are literature citing Yoldiella nana (M Sars, 1865). Reference containing the species Type Description is highlighted.
Sars M 1865. Malacozoologiske lagttagelser. Forhandlinger i Videnskabsselskabet i Kristiania. 1864: 283-315.
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