Shell up to 1,2 mm wide, planorboid, spire almost perfectly flat, very thin and fragile, colourless and transparent, widely umbilicate. Periostracum very thin, smooth and colourless. Protoconch of about 1 convex whorl, 267 µm wide, development lecithotrophic judging from morphology. Tip of apical fold broad and rounded, thereafter almost parallel-sided. Whorls smooth, with a strong rounded axial varix on adapical half of adapical surface immediately behind sigmoidal apertural rim, its adapical extremity spread onto and fused with tip of apical fold.
Teleoconch of up to 1,75 strongly and rather evenly convex whorls. Glossy, smooth apart from obscure spiral lines and very fine collabral growth lines. Umbilicus perspective to protoconch, diameter 28-31% of shell diameter. Aperture subcircular. Inner and outer lips thin. Parietal lip broad and very thin.
Animal unknown.
Known distribution. Off White Island, New Zealand, 1075-1100 m. Remarks. Xylodiscula librata differs from the Australian X. vitrea and the sympatric X. eximia primarily in having a paucispiral protoconch.