Serrata carinata, 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 : 413

Serrata carinata n. sp.

Fig. 35

TYPE MATERIAL. — Holotype (dd) MNHN 20616 .

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. 35) .

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

DESCRIPTION. — Shell ovate fusiform, thin, opaque. Protoconch paucispiral, medium-sized, bulging, eroded. Spire medium-sized, conical, whorls flat. Aperture moderately wide, very oblique, widening slightly towards base. Base slightly tapering. Outer lip very thin, very oblique, weakly arched, shoulder sloping at very low angle, outer margin slightly thickened, moderately wide, sharply bevelled, inner edge sharp, smooth. Four very thin columellar plaits, lowest one long, very oblique, faintly angled anteriorly, 3 upper ones much less oblique, decreasing regularly in size posteriorly, fourth plait nearly horizontal.

Colour brownish (stained).

Dimensions: 6.65 x 3.20 mm.

Radula unknown.

REMARKS. — Serrata carinata was found syntopically with S. laevis . It seems to form an intergrade between S. laevis and the following species. Serrata carinata matches S. laevis more closely because of its noticeably widened aperture and its truncated base. It differs from S. laevis mainly in its less inflated outline, its more attenuated spire, its slightly less widened aperture, the sharper inner border of its labrum and the carinate appearance of its outer margin. Serrata laevis itself links S. carinata and S. perlucida . Serrata carinata also appears to match the shell morphology of S. hians closely, differing principally from this species in its smaller size, its lighter shell with a thinner labrum, its less oblique columellar plaits and the more widening upper part of its aperture.

ETYMOLOGY. — Latin carina (n., convex base of a ship’s hull, the keel) and –ta (adjective suffix), referring to the angled section of the outer margin of the shell.