Calliotropis nomismasimilis

Calliotropis nomismasimilis is a species of sea snail, a marine gastropod mollusk in the family Eucyclidae.^[1]

The size of the shell varies between 4 mm and 8 mm.

The shell of the Calliotropis nomismasimilis is small for the genus, up to 5.2 mm in height and 9.1 mm in width, much broader than high and cyrtoconoidal (approaching a cone in shape, but with convex sides).^[2][1] The spire is depressed, its height about 0.5–0.6× the shell width (≈4.1- 4.7× the aperture height).^[1] The umbilicus is broad.^[1]

The protoconch is 280–300 μm, of one whorl, without a terminal varix.^[1] The teleoconch has up to 4.8 whorls: early whorls are moderately convex and later whorls slightly concave.^[1] Two granular spiral cords are present on the first whorls and three on the last whorls.^[1] Primary axial sculpture occurs only on the first whorls. The suture is deeply grooved longitudinally.^[1]

First teleoconch whorl: about 20 slightly prosocline smooth ribs with interspaces 2-2.5× rib width; granular cords P1 and P3 appear almost immediately, with nodules at rib intersections; P3 is slightly stronger.^[1]

Second whorl: beads on both cords become stronger and sharper, thicker on P3; axial ribs weaken.^[1]

Third whorl: beads of P1 and P3 broaden and are bluntly sharp; spacing between beads ≈2× bead size; P4 emerges from the suture mid-whorl, lamellose, with scaly beads that are smaller and about six times more numerous than P3 nodules; P2 is absent; axial ribs disappear.^[1]

Fourth whorl: P1 beads are nearly vertical; P4 fully emerges, leaving no gap with P3; P4 beads are smaller than P1, bluntly sharp, scaly.^[1]

Last whorl: P4 becomes peripheral and forms a keel; its beads are vertically elongated and about three times more numerous than P3 nodules; two, sometimes three, granular tertiary cords appear after mid-whorl between P1 and P3.^[1]

The aperture is imperfectly quadrangular.^[1] The outer lip is thin with a submedian angle aligned with external P3–P4 and meets the inner lip at about 120°.^[1] The columella is oblique, curved in its anterior third, bears one basal tooth, and expands into the umbilicus.^[1] The base is moderately convex with an outer smooth zone and six closely spaced granular spiral cords; spacing is about half a cord's width.^[1] The innermost cord is strongest and borders the umbilicus; stout axial ribs connect the beads of the cords.^[1] The umbilicus is wide (≈30% of shell width), deep, and tunnel-shaped, with steep walls, crowded weak axial riblets, and no internal spiral cord. The teleoconch and protoconch are hazel-beige in colour.^[1]

This species occurs in the Pacific Ocean off the Solomon Islands.

• Vilvens C. (2007) New records and new species of Calliotropis from Indo-Pacific. Novapex 8 (Hors Série 5): 1–72.

• "Calliotropis nomismasimilis". Gastropods.com. Retrieved 15 January 2019.

Media related to Calliotropis nomismasimilis at Wikimedia Commons