Ctena bella ( Conrad, 1837 )

Glover, Emily A. & Taylor, John D., 2007, Diversity of chemosymbiotic bivalves on coral reefs: Lucinidae (Mollusca, Bivalvia) of New Caledonia and Lifou, Zoosystema 29 (1), pp. 109-181 : 134-136

Ctena bella ( Conrad, 1837)

( Figs 15D ; 16 )

Lucina bella Conrad, 1837: 254 , pl. 19, fig. 11.

Lucina divergens Philippi, 1850 (April) : 103, pl. 2, fig. 4.

Lucina ramulosa Gould, 1850 (June) : 255; 1852: 415, pl. 36, fig. 523a, b.

Lucina fibula Reeve, 1850 (June) : pl. 7, figs 33, 37, 38.

Ctena bella – Dall et al. 1938: 129, pl. 35, figs 1-8. — Kay 1979: 543, fig. 176A-D.

TYPE MATERIAL. — Lucina bella : type not located (Academy of Natural Sciences, Philadelphia?).

Lucina fibula : 3 syntypes, St Elena, W Columbia (error?) and Isle of Ticao, Philippines ( BMNH 196338/1, 196339, 196337/1).

Lucina ramulosa : holotype, Paumoto, Tuamotu Islands (USNM 427778).

TYPE LOCALITY. — Although the type locality of L. bella is given as muddy marshes near San Diego, Dall (1901) and Dall et al. (1938) argue that Nuttall (collector of the shells described by Conrad) most likely collected the specimens from the Hawaiian Islands.

MATERIAL EXAMINED. — Koumac. 16 stn, 0-120 m, 33 v, 8 live.

Touho. 13 stn, 0-35 m, 65 v, 6 live.

Lifou. 37 stn, 2-38 m, 650 v, 68 live.

ChesterfieldIslands. CHALCAL 1, stn DC 27, 19°17.15’S, 158°34.05’E, 67 m, 2 v.

CORAIL 2, stn DW 148, 19°54.08’S, 158°27.12’E, 34 m, 3 v. — Stn DW149, 19°57.0’S, 158°28.0’E, 19 m, 1 v. —Stn DW 150, 19°54.0’S, 158°25.20’E, 39 m, 50 v. — Stn DW 154, 19°52.04’S, 158°26.50’E, 35 m, 2 sh, 3 v. — Stn DW 155, 19°49.08’S, 158°24.85’E, 42 m, 9 v.

Other New Caledonia. Stn 374, Grand Récif Sud, 22°30’S, 167°09’E, 70 m, 1 v. — Stn 1034, secteur de Poum, 19°58’S, 163°58’E, 23 m, 1 v. — Stn 1073, secteur de Belep, 19°60’S, 164°04’E, 28 m, 2 v. — Stn 1095, 19°53’S, 163°38’E, 29 m, 1 sh. — Stn 1102, 19°43’S, 163°54’E, 38 m, 1 v. — Stn 1106, 19°40’S, 163°53’E, 39 m, 1 sh. — Stn 1165, 19°15’S, 163°15’E, 65 m, 5 v. — Stn 1168, 19°16’S, 163°09’E, 50 m, 1 v. — Stn 1170, 19°18’S, 163°14’E, 65 m, 3 v. — Stn 1172, 19°18’S, 163°20’E, 65 m, 3 v. — Stn 1173, 19°19’S, 163°16’E, 64 m, 2 v.

Loyalty Islands. MUSORSTOM 6, stn DW 433, 20°20’S, 166°09’E, 24 m, 1 v. — Stn 1219, Lagon d’Ouvéa, 20°30’S, 166°28’E, 15 m, 1 v. — Stn 1221, 20°29’S, 166°31’E, 10 m, 5 sh, 1 v. — Stn 1224, 20°32’S, 166°28’E, 18 m, 3 v. — Stn 1227, 20°37’S, 166°25’E, 12 m, 1 sh.

DISTRIBUTION. — Widely distributed across Indian and Pacific oceans to Marquesas and Rapa.

DESCRIPTION

Small to medium sized (H to 23 mm, L to 25 mm), sub-circular, anteriorly extended. Umbones prominent. Colour white, orange pink or yellow. Protoconch 160 µm long, PI smooth, 70 µm, PII with prominent growth increments. Sculpture of strong, radial ribs that bifurcate ventrally, with new ribs intercalating into interspaces. Ribs crossed by concentric lamellae forming scales on summit of ribs. Juvenile shells with more prominent and irregular ribs ( Fig. 16E ). Lunule elongate, asymmetric, larger in RV. Hinge with 2 cardinal teeth in each valve, anterior cardinal usually small and thin; single, large posterior and anterior lateral teeth in RV and two anterior and posterior laterals in LV. Ligament short, set deeply in an obliquely triangular resilifer. Anterior adductor muscle scar medium long, detached for half of length, diverging from pallial line at angle of about 25°. Pallial line entire. Shell margin smooth.

REMARKS

Although there are likely several species of Ctena living within the IWP, identification is difficult and the genus worldwide is in need of taxonomic revision. The New Caledonia specimens are very similar to samples from Hawaii, the probable type locality of C. bella . Zuchsin & Oliver (2003) illustrate (as Ctena divergens ) very similar shells from the northern Red Sea.

Figures

FIG. 15 — Outline drawings of interiors of right valves of Codakia Scopoli,1777 and Ctena MÖrch,1861 species:A, Codakia paytenorum (Iredale, 1937); B, Codakia punctata (Linnaeus, 1758); C, Codakia tigerina (Linnaeus, 1758); D, Ctena bella (Conrad, 1837). Not to scale.

FIG. 16. — Ctena bella (Conrad, 1837): A, B, exterior and interior of left valve, Lifou, stn 1417, Loyalty Islands (MNHN); C, exterior of left valve, Koumac, stn 1282, New Caledonia (MNHN); D, E, exterior and interior of juvenile shell, Lifou, stn 1425, Loyalty Islands (MNHN); F, G, details of hinge teeth, Lifou, stn 1425 (MNHN); H, exterior of left valve, Lifou, stn 1425; I, protoconch, Lifou, stn 1425; J, detail of external shell surface. Scale bars: A-C, 10 mm; D, E, 1.0 mm; F-H, 2.0 mm; I, 100 µm; J, 50 µm.