Pseudofulvia arago, 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 : 94-96

Pseudofulvia arago n. sp.

( Fig. 4 D-F)

TYPE MATERIAL. — Holotype, live-collected cv, 27.0 × 23.3 × 17.5 mm.

TYPE LOCALITY. — BENTHAUS 2002, Austral Ridge, Arago Bank , stn 1985, 23°26.3’S, 150°44.2’W, 100- 107 m.

ETYMOLOGY. — In reference to the discovery of this species from the Arago Bank.

MATERIAL EXAMINED. — The holotype.

DISTRIBUTION. — Presently only known from the Arago Bank, Austral Islands.

DESCRIPTION

Shell medium, thin but solid, rather fragiform and inequilateral with posterior slope higher, more flattened and truncated than medio-posterior and anterior shell regions; anterior margin well rounded.

Lunular area narrow, short, very slightly depressed, smooth, with margins slightly raised but not touching umbo, no sublunule.

External colour white to light yellow on the umbonal area; interior white with yellow to yelloworange spots in the umbonal cavity.

Cardinals connected in the right valve, unconnected in the left valve.

Ribs approximately 80.

Ribs on posterior slope divided into two regions (PT1 and PT2, Fig. 2B ) of comparable size, separated by a very slight depression on the margin. Posterior zone (PT2) with 9 or 10 flatly triangular ribs, ornamented with serried tubercular scales on rib tops. Anterior zone (PT1) with approximately 9 or 10 ribs, wider and more triangular than ribs of PT2 and without ornaments. Median region with more than 60 narrow, flat to rounded ribs, with no indication of periostracal insertions.

Ocular organs absent.

ANATOMY

Siphonal area with two elongated apertures surrounded with thin, white tentacles.

MICROHABITAT

The single, live-collected specimen was recovered from 100- 107 m.

REMARKS

This taxon shares one character with the genus Fulvia , stronger ribs on the posterior slope than on the median and anterior shell regions. However, unlike most other Fulvia studied so far, Pseudofulvia arago n. sp. has a “fragiform” outline, with a relatively pronounced keel or carina, very thin ribs in the median and anterior shell regions, posterior ribs and interstices very strong and triangular, no periostracal insertions on any shell region, no granulations on the exterior shell surface and finally, no ocular organs on siphonal tentacles. Pseudofulvia arago n. sp. is distinguished from P. caledonica n. sp. by its larger adult size, absence of exterior granulations, connected cardinals in the right valve and unconnected cardinals in the left valve, no sublunule and the complete absence of periostracal insertions.

Figures

FIG. 4. — A-C, Pseudofulvia caledonica n. gen., n. sp.; D-F, P. arago n. gen., n. sp.; G-J, Acrosterigma capricorne n. sp.; I, highlighting detail of posterior and medio-posterior zones of left valve; J, highlighting medio-zones, with no herringbone structures in central region. Scale bars: 5 mm.

FIG. 2.— Morphometrics used in this study to differentiate cardiid taxa:A, delineates height (H) and length (L) measurements;B, external shell regions PT1, PT2 (typical of Pseudofulvia n. gen.); C, width (W); D, angle A, the angle formed by the most dorsal cardinal and laterals;E, I, the lunular heart and II, the lunular area (typical of Fulvia); F, I, the lunule s.s. and II, the lunular area (typical of Ctenocardia). For A, B, D the left valve is figured. Refer to Materials and methods for further description of these terms, see also Vidal (1994).