Shell angularly biconic with orthoconoid, blunt spire, b/1 0.46-0.51, a/1 0.49-0.58, whorls with rounded, median angle, subsutural slope slightly concave; suture strongly undulating on last whorl; base tapering rapidly, end obliquely rounded, not indented. Outer lip evenly convex, interior with 7-9 denticles, posteriormost the strongest; lip preceded by a moderately high, rounded terminal varix; anal sinus shallowly and asymmetrically concave, no stromboid notch; inner lip strongly calloused, columella straight, with 6-8 transverse plicae on outer edge, forming 4-6 denticles. Axial ribs from suture to base, orthocline and straight, not aligned across suture, in t/s high, rounded-angular, slightly wider than evenly concave intervals, 8-9 ribs per whorl. Spiral ridges low and thin, much narrower than their intervals, which are filled with microscopic spiral threads bearing minute granules on early whorls, 10-13 main ridges on penultimate whorl, ca 18 on base of last whorl. White, apex grey-tinged, subsutural slope with 3-5 brown-tinged spiral threads, interrupted by axial ribs. Protoconch domed, of ca 2 whorls, with short orthocline plicules at the upper suture visible under ESEM, opisthocline plicules at the lower one; breadth 0.40-0.46 mm. Teleoconch whorls 4.2.

The characteristic group of dark brown spiral threads on the shoulder slope in this species is otherwise found only in Eucithara capillatta (Hervier, 1897), a com¬mon Indo-Pacific species that also occurs in the Red Sea. But although E. capillata varies a good deal in shell breadth, the combination of biconic shape, weaker columella denticles and domed, paucispiral protoconch (instead of rounded-conical), adequately distinguish E. capillaris; furthermore, the outer edge of the columella has 6-8 denticles, instead of 9-13 as in E. capillata, and the interstitial sculpture is spiral, not cancellate as in the latter species. A probable syntype of Mangelia capillata was illustrated by Kilburn (1992: fig. 133).

Northern Red Sea, from the Gulf of Aqaba to the Egyptian mainland.