Description of Holotype: Shell of moderate size for the genus, pale flesh colored with axial markings of brown, surface glossy; aperture about 1/3 the length of the shell; suture not deeply impressed, shoulder weakly concave. Protoconch relatively large, 2 whorled, tip bulbous, slightly off center, second whorl with a low carination, postnuclear whorls 8. Axial ribs 8 on early whorls, increasing to 10 on penultimate whorl, rising to crests at the periphery and extending weakly across the shoulder and base; spiral sculpture of a faint groove delimiting the shoulder and a more definite groove separating the body whorl and pillar. Sinus deep, U-shaped, bounded by massive, curved parietal callus on the inside, nearly constricting the opening; lip edge nearly straight, slightly thickened away from the edge, stromboid notch well marked; anterior canal short, slanted to the left and deeply notched; parietal wall broad, inner lip raised. Height, 19.9 mm, diameter, 6.6 mm.

Elaeocyma amplinucis is characterized by its large protoconch, distinctive color pattern and paucity of spiral sculpture. In having little spiral sculpture it suggests the genus Cymatosyrinx Dall, 1889, but that genus has an axial swelling in back of the lip edge, while Elaeocyma does not.

Galapagos Islands. Type: James Bay, Isla Santiago .