Mesopeplum convexum (Quoy & Gaimard 1835)

“Pecten convexus, Quoy and Gaimard, 1835. Plate 56, figs. 8, a.

Shell slightly inequivalve, the right valve generally more inflated, the anterior ears somewhat larger, rounded, solid, with 4 to 5 broadly convex radiate ribs and very numerous finer ones, white spotted with pink, or reddish to purplish. Beaks minute, approximate, the prodissoconch smooth and sharply pointed. Ears unequal, the anterior ones larger; they are radially strongly ribbed, and the ribs crossed by numerous fine concentric striæ, some of which are squamose; right anterior auricle with very narrow byssal fissure, the opposite margin of the disc with a ctenolium. Discs triangular above, distinctly shouldered at the ears, rounded below, anterior end narrowly convex, posterior end a little more produced than the anterior, angularly rounded. Sculpture of discs consisting of 4 or 5 broad rounded radiate ribs and numerous small unequal and inequidistant radiate ribs, crossed by fine wavy concentric growth-lamellæ. Colour white spotted with pink or flesh-red, the right valve always of a paler colour than the left, sometimes reddish, purplish, or white with the large ribs only pink-coloured. Interior pinkish or white, shining, deeply grooved. Margins undulating, finely crenulate. Hinge-plate moderately broad, with rather indistinct cardinal crura. Resilifer small, triangular; external ligament narrow, extending the whole length of the hinge-line. Adductor-scar hardly impressed, irregularly rounded, subcentral, nearer the posterior end. Pallial line simple.

Diameter – Ant.-post., 46 mm.; dorso-ventral, 43 mm.; thickness, 20 mm.

Type in the Mus. Hist. Nat., Paris

Hab. – North and South Islands of New Zealand: Bay of Islands; Hauraki Gulf, in 25 fathoms; near Cuvier Island, in 38 fathoms; Cook Strait; Dusky Sound. Stewart Island.

Remarks – Although provided with a byssus, this mollusk has been observed swimming about. (Captain Bollons.)

The species is not common at all, and good specimens are only obtained by dredging. During the voyage of the “Astrolabe” only two empty shells were collected.

Fossil in the Miocene and Pliocene.”

(Suter, 1913)

Mesopeplum convexum is a species of scallop, marine bivalve molluscs in the family Pectinidae.