Shell fusiform, 4.5 mm, of approx. 5 whorls, spire profile very weakly convex. Protoconch smooth 1 lA whorls. Teleoconch whorls" convex, sutures impressed, whorls reticulated by axial and spiral ribs of nearly equal strength, approx. 21 axials and 7 spirals on the penultimate whorl. Final whorl roundly and gradually contracted, anterior pillar with 3 or 4 moderately prominent spiral cords. Aperture approx. 35 % total length of shell. Shell uniformly white. Columella with 4 plaits, the posteriormost very thick and massive. Upper parietal region with a small but prominent nodule of callus. Outer lip damaged, anterior canal distinct, internal lirae absent.
Type Locality
Australia, Western Australia, W. of Rottnest Island (32°01'S, 115°30E).
Distribution and Habitat
Australia, Western Australia, W of Rottnest Island (32°01 'S, 115°30E) to South Australia, SW of Cape Carnot (32°01'S, 115°30'E). Dredged in rubble at 71-178 m.
Etymology
The species is named after the 1970 expedition of the research vessel HMAS "Diamantina" on which the holotype of this species was collected.
Discussion
A very small species and general shape is similar to the South Australian species Austromitra jaffaensis (COTTON & GODFREY, 1932) (PI. 1, Fig. 3). The spiral ribs overlapping the axial ribs easily define this species.