Pillucina copiosa, Glover & Taylor, 2007

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 : 158-161

Pillucina copiosa n. sp.

( Figs 32 ; 34D )

TYPE MATERIAL. — Holotype: 1 sh, L 2.9 mm, H 2.7 mm, T 0.9 mm ( MNHN).

Paratypes: from type locality, 42 shells, 37 v ( MNHN) ; 4 v ( BMNH 20050577 ). — Figured paratypes: from type locality, 1 sh, L 1.5 mm, H 1.5 mm ; 1 RV, L 3.0 mm, H 2.9 mm, T 1.2 mm; 1 LV, L 3.3 mm, H 3.2 mm, T 1.1 mm; 1 LV, L 2.8 mm, H 2.8 mm, T 1.0 mm; 1 shell, L 2.5 mm, H 2.2 mm ( MNHN).

TYPE LOCALITY. — New Caledonia, Anse de Koumac, 20°34’S, 164°16’E, 0-2 m, Expédition Montrouzier.

ETYMOLOGY. — Latin copiosus, abundant, a reference to the frequency of the species at Koumac.

MATERIAL EXAMINED. — Koumac. 22 stn, 0-120 m, 188 v, 61 live.

Touho. 10 stn, 0-30 m, 76 v, 2 live.

Other New Caledonia. Secteur de Nouméa, Pointe Magnin, stn 1355, 7- 10 m, 5 v. — Platier Îlot Maitre, stn 1351, intertidal, 2 v.

DISTRIBUTION. — Known only from New Caledonia.

DESCRIPTION

Shell small, white to grey, H to 4.2 mm, L to 4.1 mm, moderately inflated, longer than high, ovoid to obliquely oval (H/L 0.97). Umbones prominent. Protoconch 150 µm, PI about 70 µm, PII with regular growth increments. Shell sculpture of fine radial ribs (c. 40-48), that both bifurcate and intercalate, more distinct at posterior and anterior. Ribs crossed by fine, regularly spaced, slightly elevated, commarginal lamellae.Ribs strongly divergent in anterior third of shell. Juvenile shell to around 350 µm with commarginal lamellae only. Lunule broad, lanceolate, asymmetric, greater part in right valve. RV with two cardinal teeth the posterior much larger, a small anterior lateral, and short, posterior lateral. LV with two cardinal teeth, no anterior lateral and a short, posterior lateral. Ligament internal, short, occupying an obliquely extended triangular resilifer. Anterior adductor muscle scar short, detached for about one third of length. Posterior adductor muscle scar ovate. Pallial line patchily discontinuous. Ventral shell margin slightly thickened and finely dentate.

REMARKS

Previously, Glover & Taylor (2001: 270) included the New Caledonia specimens within our concept of Pillucina pisidium (Dunker, 1860) , but the new species is smaller, more elongate, with fewer, more prominent radial ribs. Pillucina neglecta Habe, 1960 , from Japan has a more scooped lunule, a larger posterior lateral tooth and fewer ribs (c. 30). Pillucina australis Glover & Taylor, 2001 , from southwestern Australia is similar in shape and ribbing but has a prominent anterior lateral tooth in the left valve and a single cardinal tooth in the right valve.

Pillucina pacifica Glover & Taylor, 2001 ( Figs 33 ; 34C )

Pillucina pacifica Glover & Taylor, 2001: 266 , figs 2a-g, 3.

TYPE MATERIAL. — Holotype ( AMS C.355685).

Paratypes: from type locality ( AMS C.380464, BMNH 2000204).

TYPE LOCALITY. — Australia, Michaelmas Cay, Great Barrier Reef, Queensland, 16°36’S, 145°59’E.

MATERIAL EXAMINED. — Koumac. 5 stn, 12-120 m, 21 v.

Lifou. 10 stn, 4-30 m, 34 v, 1 live.

DISTRIBUTION. — Known from Queensland, Australia, Papua New Guinea, Kiribati and New Caledonia but probably more widespread in the West Pacific ( Glover & Taylor 2001: 268).

DESCRIPTION

Shell small (H to 8 mm), white, robust, inflated, obliquely ovoid, slightly higher than long (H/L 1.1). Sculpture of fine radial ribs(>50) that are slightly more prominent in anterior of the shell, broader posteriorly. Radial ribs are crossed by thread-like, commarginal lamellae giving a reticulate ornament.Ribbing is often worn in the middle part of the shell. Lunule short, broad and slightly impressed. Hinge plate sinuous, with cardinal teeth located on downward projection. RV with single prominent cardinal tooth, a thin, elongate posterior lateral tooth and a short anterior lateral.LV with two cardinal teeth of which the anterior is larger. Posterior lateral tooth a thin ridge, anterior lateral indistinct. Ligament internal, short. Anterior adductor scar short, barely detached from the pallial line,posterior scar ovate.Pallial line sometimes divided. Shell margin finely and evenly crenulate.

Figures

FIG. 32. — Pillucina copiosa n. sp., Koumac,stn 1277, New Caledonia:A, B, holotype (MNHN), exterior of left valve and interior of right valve; C, juvenile shell, right valve; D, E, paratypes (MNHN),interior of right and left valves;F, paratype (MNHN) exterior of right valve; G, paratype (MNHN), dorsal view; H, umbonal area of G; I, detail of protoconch. Scale bars: A-G, 1.0 mm; H, 200 µm; I, 50 µm.

FIG. 34. — Outline drawings of interiors of right valves of Pillucina Pilsbry, 1921, Wallucina Iredale, 1930, Chavania Glover & Taylor, 2001 and Funafutia Glover & Taylor, 2001 species: A, W. fijiensis (Smith, 1885); B, C. striata (Tokunaga, 1906); C, P. pacifica Glover & Taylor, 2001; D, P. copiosa n. sp.; E, F. levukana (Smith, 1885). Not to scale.

FIG. 33. — Pillucina pacifica Glover & Taylor, 2001, Lifou, stn 1430, Loyalty Islands (MNHN): A, exterior of left valve; B, C, interior of left and right valves. Scale bars: 2 mm.