Description (holotype): Shell small, solid, very slender (SW/SL 0.25), with high elevated spire, consisting of 1.5 protoconch and 7.25 slightly convex teleoconch whorls. Protoconch smooth, globose, elevated, diameter 850 µm, height 700 µm. Protoconch-teleoconch transition marked by strong orthocline rib after which teleoconch sculpture appears. Suture shallowly adpressed. Last whorl 0.46 SL, slightly convex. No subsutural ramp. Besides inconspicuous growth lines, axial sculpture consisting of narrow, closely spaced, and very weakly recurved, nearly orthocline, ribs. Number of ribs increasing from 12 on first teleoconch whorl to 26 on penultimate, and 33 on last whorl, extending over all whorl height on spire whorls, becoming obsolete on shell base, and hardly discernible on canal. Spiral sculpture of distinct, raised, narrow, and sub-equal cords, covering the entire shell surface, 10 on penultimate and 28 on last whorl. Cords more closely spaced on shell periphery, interspaces narrower than cords width, but more broadly spaced on base of canal. One slightly more pronounced adapical cord marks an indistinct shoulder. Cords form well pronounced knobs at intersections with axial ribs, producing an overall beaded shell appearance. Aperture 0.39 of SL, narrow-elongate, gradually passing into short and broad siphonal canal, slightly recurved to left. Outer lip thin, evenly convex. Columella slightly convex, with five poorly developed plaits, adapical one smallest. Callus narrow, of thin transparent glaze overlying parietal region. Siphonal notch absent. Shell colour very light yellow with greenish tint. Periostracum poorly developed, present in interspaces between cords and ribs, but eroded on knobs.

Belomitra hypsomitra is most similar to B. brachymitra. The differences are discussed in the Remarks section of the latter species. B. hypsomitra also has somewhat similar sculpture pattern to B. radula, but differs in having a more slender shell, a beaded shell surface, better pronounced columellar plaits, and in the nearly complete absence of a subsutural ramp.
Through its very slender shell, sculpture, and relatively well developed columellar plaits, Belomitra hypsomitra superficially resembles representatives of the family Costellariidae. Nevertheless the radula leaves no doubt about its taxonomic position.

Type locality: Fiji, Lau Group, Yagasa I., 18°43'S, 178°23'W, 392-407 m. Distribution: Known from two stations off Fiji, alive in 392-407 m, shells to 477 m