Diagnosis. A typical Calliostoma species with a rather elevated, more or less conical spire, a strong subsutural granular spiral cord, a second strong granular spiral cord making keel under the middle of the intermediate whorls, last whorls convex with numerous granular spiral cords, a weakly convex base with about 13 granular spiral cords, without umbilicus.
Description. Shell of medium size for the genus (height up to 14.2 mm, width up to 11.2 mm), higher than wide, conical in shape; spire rather elevated, height 1.2x to l.3x width, 3.3x to 3.8x aperture height; angulate periphery; anomphalous. Protoconch about 250 µm wide, of 1 whorl, rounded, covered by a network of ridges producing polygonal areas; apical fold straight with a very thin rounded terminal varix.
Teleoconch of up to 7.9 whorls, 2 first whorls convex, 3rd almost Hat. the 3 next whorls with a shoulder at P3 producing keel, last whorls convex without shoulder. Suture very poorly visible, not canaliculated. First whorl convex, sculptured by thick axial, almost orthocline ribs and 3 cords P1, P2 and P3 appearing immediately, granular by intersection with axial threads; interspace between threads l.5x to 2x larger than threads; P1 slightly weaker than other cords; suture visible, not canaliculated. On second whorl, P1 becoming as strong as P2, P3 strongest, producing a keel; distance between P2 and P3 greater than distance between P1 and P2; axial threads broader and more prosocline; suture poorly visible. On third whorl, P2 weakest, P3 strongest; bead of cords well rounded, not sharp, well separated; axial threads weakening, threads between P2 and P3 very prosocline, connecting beads of cords. On fourth whorl, S2 appearing at begin of whorl, S3 and P4 at end, P4 almost completely hidden by succeeding whorl; P3 making shoulder; axial sculpture becoming obsolete. On fifth whorl, S1 appearing; P3 and P1 still strongest, S3 almost as strong as P1. On next whorls, P1, P3 and S3 more or less of the same strength; P2, S1 and S2 much weaker, similar in size. On last whorl, P4 fully visible, peripheral, granular, weaker than other cords; tertiary cords appearing, the first between P1 and S1, the other cords appearing later between S1 and P2, P2 and S2, S2 and P3. Aperture subquadrangular; outer lip rather thin, curved; basal part rounded, producing a rounded angle with outer lip and an obtuse angle at meeting point with inner lip.
Columella nearly straight, oblique, without tooth; callus completely covering umbilicus. Base weakly convex, without axial threads and with 11 to 13 granular spiral cords, the cords in area bordering umbilicus stronger.
Colour of teleoconch orange to yellowish brown, P3 and S3 base lighter; protoconch reddish brown. Operculum corneous, circular, multispiral with a short growing edge, brown.

Based on the finely beaded cords and the conical shape, the subgenus Fautor seems to be the most appropriate for the new species. Based on the ontogeny of the spiral cords Calliostoma (Fautor) aprosceptum n. sp. resembles C (F) vaubani Marshall, 1995 from northern New Caledonia, but this species, similar in size for the same number of whorls, has a much more angulate shape and is especially characterized by a concave area between P2 and P3; it has a larger yellowish brown protoconch (from 400 to 430 µm), a spiral cord P1 appearing later than P2 and P3, smaller beads on cord and a Hatter base.
The new species resembles C. (F.) metivieri Marshall, 1995 from southern New Caledonia, but this similar in size species has a larger protoconch (about 400 µm), a spiral cord P1 appearing later than P2 and P3, lacks the keeled shoulder on the intermediate whorls and has smooth cords on the base except the 3 or 4 inner granular cords.

Northern New Caledonia, 350-574 m, living at 350-396 m.