Shell medium sized for the genus, 13.3 mm in length, thin-shelled, claviform, with rather acute apex and moderately high spire. Teleoconch of about 5 convex, weakly gradate, bluntly angulated whorls; angulation in adapical part. Suture shallowly impressed, slightly wavy. Subsutural ramp moderately narrow. Base weakly convex, slightly curved in passing to canal. Aperture oval, with short, obliquely truncated siphonal canal. Anal sinus rather weak, openly U-shaped insinuation of thin lip edge. Inner lip evenly curved, columellar part straight, parietal callus forming a narrow ridge-like pad; no fasciole. Outer lip with heavy varix behind thin lip edge; axial ribs behind varix strongly smoothed. Axial sculpture represented by strong rounded, acute, slightly arcuate and weakly opisthocline folds, running from suture to suture but much weakening on subsutural ramp and fading on lower shells base, 12 on the first whorl to about 15 on last whorl. Intervals about 2 times wider than axial ribs. Spiral sculpture represented by weak threads covering only adapical part of shell base and siphonal canal.
Protoconch papilliform, of about 1,25 to l,5 smooth whorls, fine axial ribs at transition to teleoconch. Teleoconch shell glossy, colour whitish cream with chestnut-brown spiral bands of different widths; end of siphonal canal pale cream to whitish. Interior of aperture white; protoconch cream to chestnut-brown. No soft parts were available for study.
Intraspecific variation.-Adult size of examined specimens ranges from 10.5 to 13.7 mm in length. There is little variation in shell sculpture and coloration. The axial sculpture varying in number from 11-13 per whorl on early whorls to 13-16 on last whorl and there are minor differences in the coloration (different numbers and widths of the chestnut-brown spiral bands all above on the last whorl).

Horaiclavus kilburni n. sp. differs from H. filicinctus (E. A. Smith, 1882) (type locality: Japan) by the longer siphonal canal, the stronger and less denser axial sculpture, the less compressed and differently coloured protoconch, and the completely different shell colouration.

So far known from KwaZulu-Natal (Umkomaas) and Eastern Cape (Coffee Bay).