Cyclopecten kantori, Dijkstra & Maestrati, 2015

Dijkstra, H. H. & Maestrati, P., 2015, Pectinoidea (Bivalvia: Propeamussiidae and Cyclochlamydidae) from the southwestern Indian Ocean, African Invertebrates 56 (3), pp. 585-585 : 618-619

Cyclopecten kantori sp. n.

Fig. 7A–G

Etymology:After Dr Yuri I. Kantor, leading researcher of the Department of Invertebrate Morphology at the A.N. Severtzov Institute of Ecology and Evolution, Russian Academy of Sciences in Moscow. Participant of several French expeditions.

Description: Shell up to 11.9 mm in height, fragile, subcircular, inequivalve, almost equilateral, left valve more inflated than right valve (nearlY flat), auricles dissimilar in shape, anterior auricle larger than posterior one, umbonal angle 120°, internal ribs lacking, semi-translucent whitish. Prodissoconch 220 µm long. Left valve reticulately sculptured throughout shell disc by narrow radial riblets and overrunning commarginal lirae with delicate solide nodules on intersections. On central part of disc c. 10 radial riblets per mm, c. 7–8 commarginal lirae. Reticular sculpture commences in early growth stage, radial riblets enlarge gradually in ontogeny by intercostal riblets towards the ventral margin. Commarginal lirae more prominent than radial riblets, very closely spaced in early growth stage, gradually wider in later ontogeny. Auricular sculpture similar to that of shell disc with stronger solid nodules on the intersections. Right valve sculptured with commarginal lirae, closely spaced (c. 30 per mm) near umbonal area, coarser and wider on central part of disc (c. 8 per mm). Posterior auricle continuous with shell disc, sculptured with fine close-set commarginal lirae, anterior auricle and byssal fasciole seperated from shell disc by sharply incised groove, sculptured with prominent commarginal lirae and 8 crowded radial riblets with nodular intersections. Byssal notch moderately deep, byssal fasciole narrow.

Dimensions: Holotype: Height 11.9 mm, width 11.1 mm, convexity 3.2 mm.

Type material: Holotype, pr ( MNHN IM-2007-38440). Type locality: NW MADAGASCAR: In front of Narendry Bay (14°30'S 47°27'E), - 274–325 m, live, campaign Miriky, stn CP3241, 06.vii.2009.

Distribution and habitat: So far northwestern Madagascar, living bathyally on soft substrata at - 274– 325 m.

Remarks: The morphologically closest congeneric species is the abyssally (- 2928– 2930 m) living similar sized Cyclopecten textus Dijkstra & Marshall, 2008 , recorded from the Lord Howe Rise. This species could be distinguished from C. kantori by the following characters: by shell shape ( C. textus is almost circular, C. kantori somewhat higher than wide), by shape of auricles ( C. textus has smaller auricles (c. 2 mm) measured between end of hinge and disc, C. kantori somewhat broader (2.5 mm)), by commarginal sculpture of the left valve ( C. textus has less commarginal sculpture in early ontogeny, P. kantori more close-set), and by reticulate sculpture in the central part of the disc of left valve ( C. textus more squarely, C. kantori more elongate).

A somewhat similar reticulated sculptured bathyally living species is Parvamussium retiolum Dijkstra, 1995 , recorded from the southwestern Pacific. This species could be easily distinguished from C. kantori by its more oblique elongate shape ( C. kantori sub-circular), and by its well-developed internal ribs (lacking in C. kantori ).

Figures

Fig. 7 (A–J). Cyclopecten spp.: (A–G) C. kantori sp. n., holotype: campaign Miriky, stn CP3241, (A) external view of the left valve, H = 11.3 mm, scale bar = 2 mm; (B) internal view of the left valve, H = 11.3 mm, scale bar = 2 mm; (C) external view of the right valve, H = 9.8 mm, scale bar = 2 mm; (D) internal view of the right valve, H = 9.8 mm, scale bar = 2 mm; (E) prodissoconch of the left valve, H = 11.3 mm, scale bar = 0.2 mm; (F) details of the left valve, H = 11.3 mm, scale bar=0.1 mm; (G) details of the right valve, H = 9.8 mm, scale bar = 0.2 mm (MNHN 38440). (H–J) C. kapalae Dijkstra, 1990: campaign Mainbaza, stn CC3166, (H) external view of the left valve, H=5.6 mm, scale bar = 2 mm; (I) external view of the right valve, H = 4.9 mm, scale bar = 2 mm; (J) details of the left valve, H = 5.6 mm, scale bar = 0.1 mm (MNHN).