A medium-sized Ilanga species with a moderately elevated, conical spire, a rounded to weakly subangulate periphery with some faint spiral cords, five spiral cords on first teleoconch whorl, subsutural pleats on median whorls, slightly subangulate umbilicus with axial pleats around, bordered by an internal smooth spiral cord and with axial threads and eight spiral cords inside.
Description. Shell: Medium in size for genus (H up to 6.6 mm, W to 10.3 mm), wider than high, shape conical, glossy; spire moderately elevated, height 0.64-0.76x width, about 1.91x to 2.33x aperture height; rounded to weakly subangulate periphery; umbilicus rather broad and deep. Protoconch ca. 250-300 µm wide, 1.25 whorls, rounded, with a weak straight terminal lip. Teleoconch up to 4.5 convex whorls; early whorls with five smooth spiral cords; intermediate whorls with subsutural axial pleats; last whorls smooth with some faint spiral cords on periphery. Suture canaliculated on first whorls, impressed on last ones. First teleoconch whorl convex, with five smooth spiral cords, Pi appearing immediately, similar in size; subsutural ramp with P1 near P2 on rim; distance between cords about 1.5xto 2xwidth of cords. On second whorl, all cords widening; short axial pleats appearing after half of first teleoconch whorl, covering adapical quarter of whorl. On third whorl, pleats becoming subsutural; subsutural ramp and all spiral cords vanishing. On fourth whorl, axial pleats weakening and vanishing. Last whorl completely smooth, except 6 very faint spiral cords on periphery of whorl. Aperture subtriangular; peristome incomplete; outer and inner lip thin; inner lip with a weak thickening against umbilical rim. Base moderately convex; outer part smooth, inner third with about 30 strong axial pleats around umbilicus, closer and thinner near aperture. Umbilicus broad (diameter 18-26% of shell width), central, with perspective to apex, with subangulate rim, bordered by granular spiral cord; whorl face inside umbilicus with 8 spiral cords and rather strong axial threads forming weak reticulate pattern.
Colour: Teleoconch nacreous white with brownish orange with broad brownish axial flames; base pinkish white.
Operculum: Corneous, multispiral with central nucleus, light brown, translucent.
Remarks. Regarding the strong axial threads inside the umbilicus, I. dongshaensis may be compared to I. comes from the Philippines, but I. comes is slightly larger (H up to 6.8 mm, W up to 11.3 mm), has a more depressed spire (height 0.52-0.62x width, instead of height 0.64-0.76x width here), only 4 spiral cords on the early whorls (instead of 5), a slightly broader umbilicus and a greyish white colour with brownish flames or patches.