Pusia kuboi: Shell small, up to 8 mm in length and 3.0 mm in width, relatively thin, fusiform, with a shining surface. Protoconch cylindrical to hemi-ellipsoidal, about 0.6 mm in length and 0.4 mm in width, consisting of 33,5 rounded, glossy, whitish to colourless whorls. Teleoconch of 5 to 5,5, rather flat, slightly convex whorls. Sutures distinct and whorls slightly shouldered. Whorls sculptured with moderately strong, rounded, rolling axial ribs, 15-17 on every whorl; interstitial axial furrows approximately as wide as the ribs. Spire-whorls spirally sculptured by 4-6 mostly very fine and regular grooves in the interstices of the axial ribs; the second subsutural groove deeper and wider, slightly bisecting the axial ribs, producing flat nodules at the shoulder of the whorls. Body-whorl sculptured by 13-15 shallow, spiral grooves which incise the axial ribs also below the periphery, producing spiral rows of flat nodules especially towards shell base. Indistinct siphonal fasciole with 5-6 close-set, slender, oblique cords. Aperture as long as the spire or slightly shorter, narrow, only slightly decreasing in width anteriorly; strongly spirally lirate within, with 11-12 smooth and slender lirae ending at about 1 mm from the edge, leaving the inside of the simple outer lip smooth. Parietal side of aperture glazed, inner lip scarcely protruding; prominent thick callus protuberance in the posterior aperture angle (fully developed only in mature specimens); columella with four plicae, decreasing in size anteriorly. Siphonal canal distinctly recurved to the dorsal side.
Shell ground beige; upper teleconch-whorls unicoloured beige. A typical colour pattern is developed only on the last two (or three) whorls, where most of the spiral grooves are accentuated by faint brown lines. From the suture to the third spiral groove of these whorls extends a spiral zone, tinted light brown; the second and to some extent also the third spiral groove is markedly darker brown, especially in the interstitial furrows between the axial ribs. The body-whorl is ornamented with a second light brown spiral zone, situated shortly below the periphery and extending from the sixth to the tenth spiral groove (counted from the suture). Several spiral grooves within this zone are clearly darker brown than most other grooves, especially in the interstices between the axial ribs, where small dark brown blotches may be developed in some specimens. Columella, siphonal fasciole, and interior of the aperture uniformly whitish to beige.

Pusia kuboi: The holotype and paratypcs 1 and 2 from off Okinawa were compared with and differentiated from Vexillum (Pusia) roseotinctum (Hervier, 1897) by Kubo (1997). That species is similar in size and shape, but differs distinctly from V. (P.) kuboi by the deeper and wider grooves in the interstices of the axial ribs and much more prominent nodules on the lower half of the bodywhorl. Vexillum (Pusia) roseotinctum differs clearly in colour pattern, showing reddish spiral zones below the suture and below the periphery, whereas the spiral grooves are not accentuated by a darker colour.
Vexillum (Pusia) kuboi is similar to V. (P.) goubini (Hervier, 1897).The shells of that species are more slender, with more slender axial ribs, and spiral grooves that are generally not accentuated by a darker colour. Further distinctive features of V. (P.) goubini are a sole spiral row of small, darkbrown, circular spots restricted to the interstices of the axial ribs at some distance from the suture and brown blotches inside the aperture at some distance of the outer lip.

Pusia kuboi: The species is known from the Comoro Islands, the Maldives, Papua New Guinea, Guam, and Japan (Okinawa). It occurs subtidal at 1.5-40 m on bottoms with sand and coral rubble, on reefs, in reef lagoons, and caves in drop-offs.