Imbricaria cernohorskyi (Rehder & B. R. Wilson 1975)

Ziba cernohorskyi

DIAGNOSIS.—Shell of moderate size, 32.6 mm in length, elongately biconic, body whorl subsuturally obtusely angulate, with incised spiral lines, crossed in early whorls by equidistant axial grooves. It has somewhat the shape of Ziba bacillum (Lamarck, 1811) and Z. astyagis (Dohrn, 1860), and, on the body whorl, the sculpture of Z. turtoni (E. A. Smith, 1890), but is more strongly shouldered.

RANGE.—Off Pitcairn Island, in 45–55 fms, coral and rubble bottom.

DESCRIPTION.—Shell: Moderate size, 32.6 mm in length, elongately biconic, with spire somewhat shorter than apertural length, early whorls rather straight-sided with deeply impressed, subcanaliculate sutures, later whorls increasingly convexly shouldered. Protoconch missing, 8.25 whorls remaining, early whorls with straight, strong, broad, and flattened axial ribs, about 20 in first complete whorl, crossed by 4 spiral grooves that form elongate punctations at the intersections with the intersectional punctations rounder and smaller, the intersecting equal grooves forming relatively large, flat rectangles; in the last 0.25 of the penultimate whorl, the axial grooves become irregular and obscure, and on the body whorl they disappear, leaving only 15 spiral grooves which at the base become broader between rugose ridges; the uppermost grooves below the shoulder with some irregular punctations, especially near the lip; siphonal fasciole rather pronounced, with a narrow pseudumbilicus present between it and the edge of the columellar lip callus. Aperture narrow, elongate, rather rectilinear; six folds on the columellar lip, the uppermost the largest, the others gradually diminishing in size towards the base; anterior canal short and broad, siphonal sinus distinct; outer lip simple, very slightly thickened internally and marked there by weak denticulations at the termini of the external spiral grooves. Lower half of early whorls pale grayish yellow, upper half white; body whorl grayish yellow except for white area below suture and on base, with scattered, irregular white spots and flammules in the grayish yellow area; a deep orange-yellow band present in middle of the body whorl.

Radula (Figure 9): The radular ribbon creamy white, 4.7 mm in length and 1.1 mm in width, and with 53 fully formed rows of teeth and 2 nascentes. The median tooth with nine rather slender cusps, gradually decreasing outward in size. Laterals elongate and multicuspid.

MATERIAL.—Holotype: Off NW corner of Pitcairn Island, 45–55 fms; 19 October 1967; PIT–VI: 5; USNM 707239.

MEASUREMENTS (in mm).—Length, 32.7; width, 12.3; aperture length, 19.5.

Imbricaria cernohorskyi is a species of sea snail, a marine gastropod mollusk in the family Mitridae, the miters or miter snails.