Length, 25 mm; diameter, 9 mm

Shell: broadly fusiform, anterior canal long, 'almost straight; peripheral carina noded; ivory-white, internodes of peripheral carina red-brown. Spire: slightly less than half the length of the aperture and siphonal canal; protoconch narrowly conical, of three and one-half dark brown whorls, the apical whorls smooth, the abapical whorl axially costate; teleoconch of about eight whorls. Sculpture: subsutural fold prominent, narrow-crested, smooth; shoulder slope straight, descending with crisp, smooth spiral cords; peripheral carina low-set, of two cords noduled by axially fused nodes; last whorl with eight or nine smooth cords and finer threads in the interspaces below the carina. Aperture: sinus deep, U-shaped, apex the width of the peripheral keel.Color: ivory-white sparsely maculated with red-brown, internodes of peripheral carina redbrown. periostracum pale-straw.

G. interpolata was described from the Hawaiian Islands.