Powellisetia bilirata

In the original description, Ponder described Powellisetia bilirata as follows:

Shell minute, small for genus, rather solid, semi-transparent, strongly spirally striate, yellowish brown. Whorls 4, convex, angled by a strong spiral cord in middle of whorl; protoconch of 1½ whorls, finely spirally striate, transparent, apex slightly inrolled. Body whorl rather large, periphery and base rounded. Aperture relatively small, solid, oval angled above; inner lip and columella moderately thickened, concave, columella separated from base below: outer lip weakly channelled above and below, sharp edged, a weak varix behind, and slightly thickened internally. Sculpture of fine, but distinct and regular, spiral threads, the suprasutural and middle cord strong, raised, rather sharp, the latter forming an angle on the whorls, the former being continued over periphery as a strong cord. About 6 fine spirals above, and 6 below middle cord on penultimate, about 16 on base, but these numbers vary slightly in paratypes. Strong cords constant, sometimes disappear over last part of body whorl, but usually continuous. Umbilical chink present but no true umbilicus. Colour pale yellowish-brown, protoconch reddish-brown, Animal, operculum and radula unknown.^[2]

P. bilirata has two stronger spirals on its shell, that cross over the whorls at an angle.^[3] The species measures 1.05 mm (0.041 in), by 0.68 mm (0.027 in).^[4]