Cyclopecten inoculatus, Dijkstra & Maestrati, 2017

Dijkstra, Henk H. & Maestrati, Philippe, 2017, New species and new records of littoral and bathyal living Pectinoidea (Bivalvia: Propeamussiidae, Cyclochlamydidae, Pectinidae) from the western and southwestern Pacific, Zoosystema 39 (4), pp. 473-485 : 477-478

Cyclopecten inoculatus n. sp.

( Fig. 2 A-G)

TYPE MATERIAL. — Bismarck Sea. MADEEP 2014, stn CP4251, 03°30’S, 148°02’E, 842-933 m, alive, holotype spm ( MNHN- IM-2013-44910). — Stn CP4245, 04°06’S, 148°10’E, 790-808 m, alive, paratype spm (MNHN-IM-2013-44742). — Stn CP4246, 04°07’S, 148°09’E, 695-899 m, alive, paratype spm ( MNHN- IM-2013-44801). — Stn CP4250, 03°31’S, 148°03’E, 780-855 m, alive, paratype spm (MNHN-IM-2013-44844). — Stn CP4256, 02°51’S, 150°56’E, 1200-1274 m, alive, 2 paratypes spms ( MNHN- IM-2013-45044, MNHN-IM-2013-45054).

TYPE LOCALITY. — Bismarck Sea, SE Sherburne reefs, SE Archipel Admirality Islands, 03°30’S, 148°02’E, 842-933 m (MADEEP 2014, stn CP4251).

ETYMOLOGY. — Ornamented with spoon-shaped lamellae on left valve (Latin inoculatus , adjective meaning ornamented).

DISTRIBUTION. — Bismarck Sea, live in 695-1274 m (maximum depth range), 808-1200 m (minimum depth range).

DESCRIPTION

Shell

Up to 13.1 mm high, fragile, compressed, slightly longer than wide, almost equilateral and equiconvex, auricles dissimilar in shape, anterior auricle larger than posterior, umbonal angle 80º, resilifer triangular, internal ribs lacking, opaque whitish.

Prodissoconch

145 µm long, larval shell weakly inflated and smooth.

Left valve

In early ontogeny sculptured with commarginal riblets (c. 6-8 per mm), more raised and prominent on central part of disc (4-5 per mm). Delicate intercostal radial riblets and spoonshaped lamellae on intersections of radial and commarginal sculpture commence after c. 5 mm below umbonal top, increasing downwards in number and prominence. Auricles sculptured with closely spaced commarginal lamellae, more prominent on anterior than on posterior.

Right valve

With closely and regularly spaced commarginal ridges, c. 8 per mm on central part of disc. Anterior auricle with fine, closely spaced radial riblets and strongly overrunning commarginal lamellae, with spines developed on dorsal margin of anterior hinge; posterior auricle with closely set, prominent commarginal lamellae. Byssal fasciole broad, byssal notch moderately deep.

Dimension of holotype

H 13.1 mm, W 11.9 mm, D 2.8 mm.

REMARKS

The present species is morphologically closest to its congener Cyclopecten kermadecensis (E. A. Smith, 1885) , known from the Kermadec Islands at lower bathyal depths, but differs in size ( C. inoculatus n. sp. up to 13.1 mm, C. kermadecensis up to 7.5 mm), and in sculpture of the left valve ( C. inoculatus n. sp. has regularly radially arranged spoon-shaped lamellae on the intersections, C. kermadecences has more irregularly, radially arranged curled lamellae of different prominence).

Another morphologically close congener is Cyclopecten incongruus (Dall, 1916) ( Coan et al. 2000: 249, pl. 47), known from the lower bathyal eastern Pacific. This species differs from the present species in its somewhat larger size ( C. inoculatus n. sp. up to 13.1 mm in height, C. incongruus up to 14 mm), in shape ( C. inoculatus n. sp. is more elongate, C. incongruus more circular), in sculpture of the left valve ( C. inoculatus n. sp. have strongly developed spoonshaped lamellae on the intersections, C. incongruus more delicately pustulose). Moreover, C. inoculatus n. sp. has a broad byssal fasciole, C. incongruus a narrow one ( Grau 1959: 203, pl. 13).

Figures

FIG. 2. — A-G, holotype of Cyclopecten inoculatus n. sp. (MNHN-IM-2013-44910): A, exterior rv; B, interior rv; C, exterior lv; D, interior lv; E, prodissoconch and early ontogeny of lv shell disc; F, exterior detail lv; G, exterior detail rv. Abbreviations: see Material and methods. Scale bars: A-D, 10 mm; E, F, G, 200 µm.