Serrata laevis, 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 : 412-413

Serrata laevis n. sp.

Fig. 34

TYPE MATERIAL. — Holotype (dd) MNHN 20615 .

TYPE LOCALITY. — Norfolk Ridge , 24°52’S, 168°22’E, 635-680 m [BERYX 11: stn DW 09] .

MATERIAL EXAMINED. — Norfolk Ridge. BERYX 11: stn DW 09, 24°52’S, 168°22’E, 635-680 m, 1 dd (holotype, Fig.34) .

DISTRIBUTION. — Northern Norfolk Ridge , one shell in 635-680 m.

DESCRIPTION. — Shell ovate fusiform, thin, subtranslucent. Protoconch paucispiral, wide, dome-shaped, smooth. Spire moderate-sized, triangular, blunt, whorls weakly convex. Aperture wide, very oblique, widening slightly towards base, nearly parallel-sided. Base faintly tapering. Outer lip thin, weakly arched, subvertical, shoulder sloping, faintly angled at contact with last whorl, rounded, outer margin narrow, rounded, stepped, inner edge smooth. Four thin columellar plaits, very oblique, lower one long, subvertical, weakly angled over anterior part, 3 upper ones decreasing in size posteriorly.

Colour whitish (faded).

Dimensions: 5.10 x 2.20 mm.

Radula unknown.

REMARKS. — The shell morphology of Serrata laevis is very similar to that of S. perlucida , principally in the hyaline and juvenile appearance of the shell, the rather tall, massive spire with convex whorls, the wide aperture with a thin, smooth labrum, the narrow, rounded, stepped outer margin, and the thin, oblique, columellar plaits arranged in a fan-like pattern, with the lowest one weakly angled and subvertical. As in S. perlucida , the outer margin is stepped and well-marked. Serrata laevis differs from S. perlucida principally in its thicker shell, its less inflated shell outline, its less widened aperture and its less thin and sharp outer lip. The single shell was found at a shallower depth and further south than the 4 specimens of S. perlucida .

ETYMOLOGY. — Latin laevis (adj., light, not heavy), referring to the fragile consistency of the shell.