Serrata arcuata, Boyer, 2008

Boyer, Franck, 2008, The genus Serrata Jousseaume, 1875 (Caenogastropoda: Marginellidae) in New Caledonia, Mémoires du Muséum national d'Histoire naturelle 196, pp. 389-436 : 423

Serrata arcuata n. sp.

Fig. 50

TYPE MATERIAL. — Holotype (dd) MNHN 20627 .

TYPE LOCALITY. — Off southwestern New Caledonia, 22°05’S, 165°58’E, 250-300 m [BATHUS 4: stn DW 885] .

MATERIAL EXAMINED. — Southwestern New Caledonia. BATHUS 4: stn DW 885, 22°05’S, 165°58’E, 250-300 m, 1 dd (holotype, Fig. 50) .

DISTRIBUTION. — Southwestern New Caledonia, one shell in 250-300 m.

DESCRIPTION. — Shell outline asymmetrical, rather subpyriform on left side and curved on right side. Moderately solid, opaque. Protoconch paucispiral, wide, low, smooth. Spire very short, wide, low, subconical, whorls weakly convex. Aperture subvertical, lower two thirds markedly open. Base rather wide. Outer lip smooth, arched, moderately thickened, shoulder slightly sloping, short, outer margin thick, protruding, flat, stepped, inner edge smooth, almost vertical over upper third, very slightly concave over lower two thirds. Four prominent columellar plaits, 2 lowest long, sinuous, oblique, 2 uppermost ones shorter, less oblique, very produced. Anterior plait tends to encompass border of siphonal canal.

Ground colour whitish (faded).

Dimensions: 5.10 x 2.80 mm.

Radula unknown.

REMARKS. — The shell morphology of S. arcuata is characterized by its arched labrum with smooth inner edge and its rather long and wide aperture, combined with a rather slender outline, a subpyriform left side, a short spire and a truncated base. In the shape of its aperture and its outer lip, S. arcuata matches the S. hians group, whereas it matches the S. boucheti group in the other features.

ETYMOLOGY. — Latin arcuatus (adj., arched), referring to the curved labrum of this species.