Falsolucinoma leloeuffi Cosel 2006, n. comb.

Falsolucinoma leloeuffi (Cosel, 1989) n. comb.

(Figs 7; 8)

Lucina leloeuffi Cosel, 1989: 315, 316, pl. 1, figs 1-3.

TYPE MATERIAL. — Holotype: E Liberia, off Cap des Palmes, c. 4°10’N, 7°40’W, 250 m, dredged RV Reine Pokou, 13.X.1971, leg. Le Loeuff (IRD), 1 lv. (MNHN).

Paratypes: same locality, 2 lv. (MNHN). TYPE LOCALITY. — Cap des Palmes, E Liberia, tropical

West Africa.

OTHER MATERIAL EXAMINED. — Cameroon. 1 spm (MNHN) taken by RV Fridtjof Nansen during a cruise off the coast of Cameroon for FAO purpose. Data of the specimen unknown.

DISTRIBUTION. — Gulf of Guinea, apparently from western Côte d’Ivoire to Cameroon.

DESCRIPTION

Shell large, up to 56 mm long, length/height ratio 1.2, relatively thin-shelled, but solid, inequilateral, compressed, subcircular-triangular-rostrate, slightly variable in outline and length/height ratio. Beaks situated at or just behind the anterior third of the valve. Anterior part triangular-rostrate, anterior margin pointed. Posterior part broad, posterior margin obliquely truncate. Postero-dorsal corner rather broadly rounded. Antero-dorsal margin nearly straight, postero-dorsal margin slightly convex. Ventral margin behind the anterior point slightly concave, then to postero-ventral corner evenly rounded, this latter narrowly rounded.

Exterior with 10-15 conspicuous, prominent, thin, raised and widely spaced commarginal lamellae: 15 in the holotype, 10 and 14 in the paratypes, which on the early and middle part of the valves are evenly spaced, and may become slightly more closely spaced ventrally. Interspaces smooth, with shallow commarginal growth waves. Posterior area with a broad and shallow radial depression, separated from the disk by a broadly rounded posterior angle. Anterior area with a well marked and sharp radial depression, ending in a sinuosity in the upper anterior margin. Anterior angle narrowly rounded.

Hinge plate narrow, in the left valve with a small anterior cardinal and a narrow lamellar posterior cardinal, a strong anterior lateral and a narrow and long posterior lateral and above both more or less strong, tooth-like reinforcements. Right valve with a short, thick, bifid and only slightly inclined anterior cardinal and a thin, oblique posterior cardinal.Two anterior laterals with a deep depression between them; lower lateral more forward placed than upper lateral. Lower posterior lateral narrow but rather strong, upper posterior lateral thin and much weaker. Ligament short. Lunule very short and small, deeply sunken, slightly asymmetric, escutcheon almost entirely filled by the ligament. Adductor scars small, anterior scar with short, rather narrow and somewhat tapering diverging part, pallial line meeting the scar about in its middle. Inner margin of valves not visibly and regularly crenulate but with shallow radial waves on the zone between pallial line and margin and sometimes a few vestiges of irregular crenulations.

Valves entirely white; periostracum rather strong, almost white-translucent to pale straw-coloured or brownish, often peeling off in the interspaces of the lamellae.

Measurements are provided in Table 3.

REMARKS

As for the genus. The most similar looking species is Lamellolucina jawa Taylor & Glover, 2002, from Madura, Indonesia. It has a similar general shell shape, a similar hinge dentition and also extremely small adductor scars but is distinguished by the smaller size, the more circular outline, the presence of a finely and regularly crenulate margin and much more densely spaced commarginal lamellae. Falsolucinoma leloeuffi n. comb. was described only from three right valves, but fortunately now a single complete live-collected specimen, albeit without any precise data, became available. It was trawled by the RV Fridtjof Nansen in the Gulf of Guinea, apparently off Cameroon; the known range is thus extended considerably eastward.