Fulvia (Laevifulvia) subquadrata, 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 : 90-93

Subgenus Laevifulvia Vidal, 1994

Fulvia (Laevifulvia) subquadrata n. sp. ( Fig. 3 G-I; Table 3)

TYPE MATERIAL. — Holotype: cv, 6.4 × 6.4 × 4.7 mm. Paratypes (4): 1 lv, 8.3 × 8.0 × (6.4) mm; 1 lv, 8.0 × 8.0 × (6.0) mm; 1 rv, 6.8 × 6.6 × (4.8) mm; cv, 6.0 × 6.1 × 4.6 mm.

TYPE LOCALITY. — Expédition MONTROUZIER 1993, Baie de Touho, E coast of New Caledonia, stn 1250, 20°46.7’S, 165°13.7’E, 3-6 m, in sandy mud (paratypes come from type locality).

ETYMOLOGY. — In reference to the quadrate character of the shell that differentiates it from other small or juvenile Fulvia in this region.

MATERIAL EXAMINED. — New Caledonia. Expédition MONTROUZIER 1993, Baie de Touho, stn 1250, 20°46.7’S, 165°13.7’E, 3-6 m, sandy mud, numerous

cv and valves. — Baie de Touho, stn 1237, 20°49.9’S, 165°13.8’E, 0-1 m, fine sand, numerous cv and valves. — Anse de Tiouandé, stn 1267, 20°43’S, 165°02,0’E, 0 m, fine sand, 1 valve. — Baie de Gatope, stn 1295, 20°58’S, 164°39.5’E, 0 m, fine sand, 1 rv + 1 lv.

Solomon Islands. SALOMON 1 2001, stn 1767, 8°19.4’S, 160°39.9’E, 98-200 m, 4 valves. — Stn 1768, 8°21.4’S, 160°41.8’E, 194-286 m, 1 rv.

DISTRIBUTION. — Known from the northern part of New Caledonia and the Solomon Islands.

DESCRIPTION

Shell very small to small (max.H = 8.8, L = 9.0 mm), subquadrangular;almost symmetrical.Posterior margin quite straight and forming a weak, rounded angle with the middle third of the shell. Anterior margin rounded and slightly angled in the lunular area.

Lunular area narrow, flattened,occasionally slightly concave in the right valve; lunular heart small and well-formed; sublunule short.

Colour uniformly red-brown, rarely entirely white, shell neither translucent nor glossy; except for lunular region that ranges from white to translucent.

Ribs 36-42.

Posterior third of valve sculpted by approximately 10 rounded ribs with rounded interstices of comparable width. In middle and anterior shell regions, ribs becoming narrower, flatter and least distinct in median third of valve. Periostracal insertions absent along the ribs. Entire external shell surface of adult specimens covered with abundant, pronounced, irregular granulations, except on lunular and sublunular areas.

MICROHABITAT This species has been live-collected from 0-6 m in fine to muddy sand in Baie de Touho, New Caledonia.

REMARKS

Fulvia (Laevifulvia) subquadrata n. sp. lacks periostracal insertions on the external shell surface, like other Laevifulvia species, but unlike F. ( Fulvia ). Fulvia (L.) subquadrata n. sp. is most similar to juvenile specimens of F. (L.) undatopicta among small, co-occurring Laevifulvia . However, it is smaller (adult comparison), much more tumid, more subquadrate, more uniform in colour, with stronger ribs and stronger and much more numerous, sporadically-distributed granulations ( Table 9).

Fulvia (Laevifulvia) imperfecta n. sp. ( Fig. 3 J-L)

TYPE MATERIAL. — Holotype: cv, 10.9 × 10.3 × 5.8 mm. Paratype: cv, 8.4 × 8.2 × 4.3 mm.

TYPE LOCALITY. — SALOMON 1 2001, E of Guadalcanal, Solomon Islands, stn CP 1809, 9°48.4’S, 160°51.0’E, 39- 53 m.

ETYMOLOGY. — In reference to the “imperfect” character of lacking ribs on the posterior half of the posterior slope (zone PT 2).

MATERIAL EXAMINED. — Solomon Islands. SALOMON 1 2001, E of Guadalcanal, stn CP 1809, 9°48.4’S, 160°51.0’E, 39-53 m (holotype).

Philippines. Bohol Island, Pipe Point, 1 cv paratype, 8.4 × 8.2 × 4.3 mm (Ter Poorten collection).

Indonesia. Irian Jaya, Ostheimer Orr, stn 489, 1 cv, ANSP 206060 (fide Ter Poorten). — Not specified locality, 1 cv, 17.2 × 15.2 × 9.4 mm, 74 ribs ( MNHN, H. Fischer collection).

DESCRIPTION

Shell small, thin, rounded and compressed, symmetrical, very slightly oblique.

Lunular area poorly differentiated, smooth; lunular heart long and very narrow, hardly visible in right valve; sublunule approximately as half as long as hinge.

Shell translucent with numerous, small, irregular, longitudinally-arranged brown splashes, most intense along the medio-anterior margin. Shell interior reflects exterior by transparency.

Hinge plate characteristic of the genus Fulvia ( Vidal 1994: 97) in being narrow, thin and moderately curved (120-150°), occasionally angled in the anterior, but different in this taxon as notably and consistently red in coloration.

Ribs approximately 76.

Six to seven large ribs on the posterior slope, close to the median shell region (zone PT1, Fig. 2B ), are coloured by white splotches observable both on the exterior and interior of the shell. The remaining part of the posterior margin (zone PT2, Fig. 2B ) is larger than PT1, smooth and without marginal crenulations. Ribs of the anterior and median shell regions (zones AT1 and MT, Vidal 1994) are virtually impossible to discern externally, but clearly evident as internal marginal crenulations, about 70 in number. Periostracal insertions absent along the ribs.

REMARKS

Fulvia (L.) imperfecta n. sp. is attributable to Laevifulvia because it lacks periostracal insertions on the external shell surface.Unlike co-occurring congeners, F. (L.) imperfecta n. sp. lacks any evidence of ribs on the posterior part of the posterior slope (zone PT 2). Although many other character combinations also distinguish F. (L.) imperfecta n. sp. from the other new species of Fulvia described here ( Table 9), this character most readily distinguishes this taxon from all others.

Figures

FIG. 3. — A-C, Fulvia colorata n. sp.; D-F, F. vepris n. sp.; G-I, F. subquadrata n. sp.; J-L, F. imperfecta n. sp. 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).