Smithsonian National Museum of Natural History

Original Description
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“Arca (Barbatia) novae-zealandiae, n. sp. Pl. II, figs. 1, 2.

Arca decussata of New Zealand authors (non Sowerby).

Arca (Barbatia) decussata: Suter, Man. N.Z. Moll., p. 848, pl. LVI, figs. 2, 2a (1913).

This species, hitherto confused with A. decussata, may be recognized by the minute crenulation on the anterior and posterior inner margins of the valves, and also by both the exterior and interior being more or less stained with a reddish tint. Neither of these features is met with in the true decussata, which is always pure white within and without, and its lateral margins are broader, flattened, and invariably smooth. Although very similar externally, it may be observed that the radiating sculpture upon the posterior dorsal area is finer than in A. decussata, and more distinctly defined by an obtuse, rounded umbonal ridge. The posterior adductor impression in A. decussata is large and round, whereas in A. novae-zealandiae it is obliquely truncate behind.

Length, 67 mm.; height, 36; diameter, 24.

Station 96, north of New Zealand: 70 fathoms.

The three characters above referred to –(1) the crenulation of the lateral margins; (2) colour; (3) fine posterior dorsal sculpture – should, I think, be sufficient to separate this species from A. decussata of Sowerby.

Similar marginal crenulation occurs in Arca fusca, Bruguiere, of which A. rodatzi, Dunker, is a synonym.”

(Smith, 1915: 88-89; Pl. II, figs. 1, 2)