Shell elongately fusiform, length to 21.9 mm, Protoconch globose-paucispiral (2 whorls), teleoconch 9 whorls, spiral whorls with 3-4 spiral cords, the first cord just below the suture distinctively axially grooved, the spiral groves between the spiral cords are also axially grooved and striate; body whorl with 15 spiral cords, the first 7 cords (counted from suture) being flat and wide, the remaining cords becoming more narrow and axially striate as are the spiral grooves; columella with 4 plaits, siphonal notch deep and U-shaped, outer lip thick and slightly nodose, inner lip thin and slightly elevated from the shell surface. The whole shell is beige in colour. Etymolog: Latin sutura, a seam, a line of joining or closure and strigata a stripe in reference to the stripe along the whorls.

Only known from one specimen, however the specimen is in very good condition and very distinctive from any other Western Australian Pseudonebularia. The uniform shape and coloration of P. suturistrigata n. sp. can be compared to Pseudonebularia cuyosae (POPPE, 2008) Pseudonebularia indentata (G. B. SOWERBYII, 1874) and Pseudonebularia maesta (REEVE, 1845). However, the spiral cords in P. suturistrigata n. sp. are regularly spaced with minute spiral pits in contrast to the other three comparable species. The spiral sculpture of P. maesta compares most closely to P. suturistrigata n. sp. however the squat inflated final whorl and shorter aperture, in relation to overall shell length are differential factors.

Australia, north Western Australia, Dampier Archipelago, Malus Island (20°30.90' S, 116°40.22' E).