Serrata summa, 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 : 398

Serrata summa n. sp.

Fig. 9

TYPE MATERIAL. — Holotype (dd) MNHN 20586 .

TYPE LOCALITY. — Norfolk Ridge, 23°18’S, 168°15’E, 266-267 m [NORFOLK 1: stn DW 1723] .

MATERIAL EXAMINED. — Norfolk Ridge. NORFOLK 1: stn DW 1723, 23°18’S, 168°15’E, 266-267 m, 1 dd (holotype, Fig. 9) .

DISTRIBUTION. — P Bank, northern Norfolk Ridge, one shell from 266-267 m.

DESCRIPTION. — Shell slender subcylindrical, solid, opaque. Protoconch paucispiral, medium-sized, slightly bulging, smooth. Spire short, conical, whorls flat. Aperture narrow, long, vertical, widening gradually over its lower three quarters. Base moderately tapering. Outer lip moderately thickened, vertical, slightly arched, slightly more reflected at its posterior part. Shoulder sloping, weakly demarcated, rounded, outer edge slightly arched, outer margin narrow, slightly thickened, rounded, weakly stepped, inner lip weakly reflected over its upper third, slightly excavated below, bearing 12 low, subequal denticles, much smaller than the interspaces, the largest denticles bordering the siphonal canal. Four moderately thickened columellar plaits, anterior one oblique and sinuous, second longer, oblique, almost straight, 2 upper ones shorter, less oblique. A small horizontal fold just above fourth plait.

Ground colour horn-shaded beige (faded).

Dimensions: 4.40 x 2.05 mm.

Radula unknown.

REMARKS. — Serrata summa closely resembles the next species in general morphology, but differs in its smaller size, its more numerous and smaller, blunt denticles along the whole length of the inner lip, and its larger and more horizontal fourth plait. The upper fold may be a variable feature and is not considered diagnostic.

ETYMOLOGY. — Latin summus (adj., at the top), referring to the place where the species was discovered, on the crest of a seamount.