Shell up to 1,02 mm wide, depressed-turbiniform, broader than high, spire up to 0,38 x height of aperture at maturity, umbilicate, thin, colourless and translucent. Periostracum very thin, smooth, pale buff.
Protoconch 183-200 µm wide. Tip narrowly rounded, slightly inrolled. Sculptured throughout with fine, crisply defined, densely crowded, anastomosing vermiculate granules. A rounded varix immediately behind sigmoidal apertural rim.
Teleoconch of up to 1-5 whorls, end of mature body whorl descending more obliquely and steeply than before. First 0,5 whorl rather evenly convex, thereafter slightly flattened above and below weak peripheral and basal angulations. Sculptured throughout with numerous, fine, crisply defined, similarly and regularly spaced, reticulating spiral threads and collabral axial riblets. Spirals slowly multiplying by intercalation, similar throughout. Axials and spirals similar on spire and periphery, axials almost obsolete on base. Axials gently flexed at peripheral and basal angulations. Umbilicus narrow, rim sharply angulate, wall steep and smooth apart from collabral growth lines. Aperture D-shaped. Peristome thin, parietal contact area narrow, roundly angulated against peripheral and basal angulations.
Radula oo + l + l + l + oo. Central and lateral teeth long and rather narrow, subtriangular, very thin in section. Cutting areas rounded, with numerous small, narrow sharp cusps. Marginal teeth long, very slender and flattened, cutting areas with numerous small, sharp, slender cusps. Shafts simple.
Known distribution. Off White Island, New Zealand, 1075-1100 m.
Remarks. Bathyxylophila pusilla differs from the Australian species B. peroniana and the sympatric B. excelsa in being smaller relative to the number of whorls, in having fewer spiral threads, and in having obsolete basal axial threads.