Ctenocardia fijianum, Vidal & Kirkendale, 2007

Vidal, Jacques & Kirkendale, Lisa, 2007, Ten new species of Cardiidae (Mollusca, Bivalvia) from New Caledonia and the tropical western Pacific, Zoosystema 29 (1), pp. 83-107 : 98

Ctenocardia fijianum n. sp.

( Fig. 5 A-D; Table 6)

TYPE MATERIAL. — Holotype, 1 lv, 12.0 × 9.9 × (9.0) mm; Paratypes (2): 1 rv, 9.0 × 7.2 × (6.0) mm; 1 rv, 6.9 × 5.7 × (4.6) mm.

TYPE LOCALITY. — Fiji Islands. SUVA 4, Viti Levu, Beqa Lagoon, stn DW 15, 18°23.3’S, 178°10.5’E, 32-34 m (paratypes come from type locality).

ETYMOLOGY. — Named after the Fiji Islands, the type locality.

DISTRIBUTION. — Presently only known from Fiji Islands, south coast of Viti Levu, Beqa Lagoon.

DESCRIPTION

Shell small (holotype is the largest known: 12.0 × 9.9 × (9.0) mm), inequilateral. Posterior slope with a pronounced keel, forming a point on the ventral margin. Anterior and median slopes of the valve rounded and slightly concave just in front of the posterior slope; posterior slope very concave.

Lunular area small with a raised margin. Lunule small and flat, hardly differentiated from the lunular area.

Shell grey-white externally (although specimens may be more colourful in life), with pink spot on the lunular area close to the lunule. Interior grey- white, the external pink spot present internally, elongate and restricted to the hinge.

Anterior laterals slightly closer to cardinals than to the posterior lateral(s). Second small posterior lateral not observed.

Ribs 38-41.

Highly ornamented, square-sided, flat-topped ribs, receding anteriorly on the anterior region of the valve and posteriorly on the posterior slope. Interstices much narrower than ribs and finely striated; on posterior slope, the tops of ribs with thin, arched, concentric lamellae that become broader and longer and often overhang interstices; broader lamellae irregularly distributed and separated by a variable number (3-20+) of smaller lamellae. Ornamentation of anterior similar to posterior.

MICROHABITAT

Ctenocardia fijianum n. sp. was recovered from depths of 32.0- 35.6 m.

REMARKS

Ctenocardia fijianum n. sp. is most similar to Ctenocardia gustavi n. sp. (next entry), in size, shape, lunule and rib features. However, it differs from C. gustavi n. sp. in four main aspects, including: 1) a steeper posterior slope (as examined from keel to most posterior rib); 2) median region of the shell adjacent to the posterior slope more concave, and coupled with a more pronounced keel, results in a more angular shell outline; 3) a shallower lunule; and 4) pronounced recession of the flat rib tops.

Figures

FIG. 5.—A-D, Ctenocardia fijianumn.sp.;E-G, C.gustavi n.sp.,detail of lamellae on medio-anterior zone;H-J, C.(Microfragum) subfestivum n. sp., detail of lamellae in median zone; K-M, C. (M.) festivum (Deshayes, 1855), detail of lamellae in median zone. Scale bars: 5 mm.