Serrata aureosa, 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 : 402-403

Serrata aureosa n. sp.

Figs 17, 18

TYPE MATERIAL. — Holotype (lv) MNHN 20597 and 1 paratype (dd) MNHN 20598 .

TYPE LOCALITY. — Southern New Caledonia , 22°54’S, 167°17’E, 525-547 m [BATHUS 2: stn DW 721]. MATERIAL EXAMINED . — Southern New Caledonia. BIOCAL: DW 721, 22°54’S, 167°17’E, 525-547 m, 1 lv (holotype, Fig. stn DW 46, 22°53’S, 167°17’E, 570-610 m, 1 dd (Fig. 18). — BA- 17) and 1 dd (paratype) .

THUS 2: stn DW 720, 22°52’S, 167°16’E, 530-541 m, 2 dd; stn

DISTRIBUTION. — Southern New Caledonia, live in 525-547 m, shells in 541-570 m.

DESCRIPTION.— Shell ovate subcylindrical, solid, subtranslucent. Protoconch paucispiral, small, slightly bulging, smooth. Spire short, conical, whorls flat. Aperture moderately open, subvertical, widening towards base. Base moderately tapering, rather rounded. Outer lip regularly thickened, slightly reflected in centre. Shoulder slightly sloping, outline irregular making a double angle, central part of outer edge of the lip subvertical, anterior part weakly arched above base, outer margin thick, protruding, flat, stepped, inner edge subvertical, weakly convex, weakly excavated anteriorly, bearing 17 small denticles smaller than the interspaces, 3 tiny closely spaced denticles along siphonal canal, 14 subequal small ones along entire length of inner lip. Four prominent columellar plaits, 2 anterior plaits sinuous, oblique, second one very long, 2 upper ones simple, less oblique, decreasing in size posteriorly. One very small pleat just above upper columellar plait.

Ground colour creamy white, opalescent on ventral side, very pale amber on dorsum, medium golden amber to left of columellar plaits and on outer margin. Base, aperture and spire whitish.

Dimensions: 6.05 x 3.05 mm.

Radula unknown.

REMARKS. — Serrata aureosa , known from one seamount, appears somewhat variable in the number (13-17) of its more or less sharp labial denticles, the more or less reflected inner labrum, and the thickness of its columellar plaits. The shell outline and the shape of the aperture are more constant. The labial denticles are lacking in some specimens (Fig. 18). The shell decoration of only the live-collected holotype is described, as it is not distinct in the other specimens, except for a pale orange mark at about the posterior end of the margin in most specimens.

Serrata aureosa looks quite distinct from the other species in the S. boucheti group. It differs from S. orientalis principally in its more cylindrical and less stout shell outline, its slightly shorter and less pointed spire, its less rounded labial shoulder, and its narrower and less reflected outer lip with smaller denticles.

ETYMOLOGY. — Latin aureosus (adj., tending to gold), referring to the golden colour of the shell.