Leucosphaera Taylor & Glover, 2005

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 : 116

Genus Leucosphaera Taylor & Glover, 2005

Leucosphaera Taylor & Glover, 2005: 331 .

TYPE SPECIES. — Lucina (Loripinus) salamensis Thiele & Jaeckel, 1931 (original designation).

DIAGNOSIS. — Shells small (<10 mm), inflated, thinshelled, white to translucent. Outline ovoid, longer than high. Posterior shell margin often truncated. Shell anteriorly extended. Sculpture of regularly spaced, thin commarginal lamellae.Hinge narrow, normal hinge teeth absent. Small knob lies below the umbones of both valves contiguous with thin flange on the anterior part of the hinge ( Fig. 4G, H ). Ligament narrow, short, set in shallow groove. Anterior adductor muscle scar short, ovoid to reniform in outline, slightly detached from the pallial line. Pallial line entire, sometimes with dorsal extensions. Shell margin with thin peripheral groove.

REMARKS

Shells of this newly described genus have been confused with juvenile Anodontia in museum collections but can be separated by the ovoid shape, the regularly spaced, fine commarginal lamellae, and the extremely short, slightly detached anterior adductor muscle scar. The hinge bears a tooth-like central knob extending anteriorly as a flange. We are uncertain whether the knob is homologous with normal cardinal teeth of other lucinids. In addition to the type species and Leucosphaera diaphana n. sp. described below, we are aware of undescribed taxa from the Indo-Pacific, including Philippines, Malaysia, Maldives and the Seychelles.It is likely that Leucosphaera species are widely distributed in offshore muddy habitats but further work is needed to review the genus in detail.

Figures

FIG. 4 — Leucosphaera diaphana n. sp.: A, B, holotype (MNHN), outside of left valve and inside of right valve, secteur de Yaté, New Caledonia, stn 622; C, paratype (MNHN), exterior of right valve, Passe de Touho, stn 1249, New Caledonia; D, paratype (MNHN), interior of left valve; E, paratype (MNHN), exterior of left valve; F, paratype (MNHN), interior of right valve; G, H, details of hinge of E and F; I, J, dorsal views of G, H; K, protoconch. Scale bars: A-F, 1.0 mm; K, 100 µm.