Diagnosis: Shell moderately large (50 mm), b/1 0,28-0,29, a/1 0,34-0,37, whorls only moderately convex, scarcely shouldered, siphonal canal moderately long, tip obliquely truncate, with very shallow notch; aperture narrow, fasciole sometimes fairly strong, labrum weakly crenulate, stromboid notch slight, anal sinus narrowly U-shaped with parallel sides, parietal nodule fairly large, tongue-shaped, directed adapically, situated at suture; subsutural cord strong, on later whorls slightly narrower than the moderately deep, slightly concave shoulder sulcus; axial ribs thin, almost orthocline, terminating at sulcus, 14-16 on penultimate whorl, bearing small, somewhat rounded nodules where crossed by spiral cords, which in rib intervals are more or less equal to their interstices, 5-6 spirals below sulcus on penultimate whorl, with an occasional intermediary, sulcus with 2-5 fine spiral threads; growth-threads coarse; terminal varix mid-dorsal, an occasional varix on spire. Buff, peripheral zone and subsutural cord orange-brown, shoulder area and rostrum cream. Protoconch narrowly domed, of about 1,5 whorls, breadth 0,80-0,85 mm.

Description: Shell narrowly claviform, b/1 0,28-0,29, a/1 0,34-0,37, with narrow aperture and moderately long, fairly narrow rostrum, bent slightly to right and terminating obliquely; 11,5 teleoconch whorls; suture moderately deep; whorls moderately convex, barely shouldered, periphery more or less median, shoulder sulcus moderately deep, slightly concave, subsutural cord fairly strong, angular, on later whorls somewhat narrower than sulcus; left side of base of body whorl concave, fasciole sometimes fairly strong, false umbilicus distinct. Aperture as in I. nodicostatus but somewhat narrower, parietal nodule consisting of a thick, tongue-shaped projection, adapically directed above suture, and slightly restricting entrance to anal sinus, which is shaped like a ‘U’with parallel sides; siphonal canal not indented terminally. Sculptured by thin, moderately strong axial ribs, ending abruptly at shoulder, and weaker spiral lirae, which bear small, rounded tubercles where they cross ribs, and even smaller, very inconspicuous and irregular granules where the lirae are crossed by the relatively strong growth-lines; dorsum of body whorl with a strong, rounded varix (situated about one-third whorl back from lip), spire also with an occasional varix. Axial ribs much narrower than their intervals, with rounded crests and gently sloping sides, almost orthocline, almost straight on spire, gently sinuous on body whorl, extending well onto rostrum; subsutural cord with fine axial plicules next to suture; 7-8 ribs on 1st teleoconch whorl, increasing to 14-16 (including varices) on penultimate whorl, becoming weak and irregular after last varix. Spiral lirae relatively low and gently rounded, mostly subequal in width to one another and to their intervals, except for an occasional weaker intermediary and in the shoulder sulcus, which bears 2-5 finer threads; 5-6 lirae below shoulder on penultimate whorl, evidently 3 on 1st whorl; 15-19 main spirals on base of body whorl, where more widely spaced and with more numerous intermediary threads than elsewhere, on rostrum somewhat lower and more angular. Yellowish-white with a strong to light brown spiral band at level of parietal tubercle, occupying anterior third of each spire whorl; base of body whorl and subsutural region more or less tinged with moderate to dark orange-yellow, basal lirae white; interior of aperture brown-tinged, external brown band also visible; protoconch white. Protoconch narrowly domed, of 1,5 gently convex whorls, 1st one depressed, smooth except for a few weak, terminal axial plicules; breadth 0,80-0,85 mm, height 0,70-0,75 mm (b/h 1,01-1,21). Dimensions: 39,3 x 11,1 mm (holotype), 49,8 x 13,1 mm (paratype, pro¬toconch missing). Operculum as in I. nodicostatus, translucent moderate yellowish-brown. Tentacles small, flattened, eye about ¾ length from tip. Radula of about 35 rows of marginal plates, which resemble those of I. nodicostatus although they are somewhat shorter.

South-Africa. Outer continental shelf from Zululand to eastern Transkei, 62-115 m.