Etymology. Named after Dr Bill Rudman (Malacology Section, Australian Museum) for his extensive contribution to Australian malacology and his assistance in this and other projects.

Type material examined. HOLOTYPE: AMS CI74626. Type locality: 17°09.42'S 146°42.24'E, off Cairns, Qld, 668 m, 13 October 1981. Length of holotype 2.38 mm, aperture diameter 0.63 mm, apex diameter 0.66 mm; greatest width of shell 1.59 mm. PARATYPES: 1, AMS C173407, same locality data as holotype.

Description. Shell dimensions as for holotype; small, glossy; devoid of sculpture; barrel-shaped, very inflated centrally, more inflated on the ventral edge. Aperture circular, wider than the apex. Apex circular, shorter and more narrowly tapering than the aperture. Colour porcelaineous white.
Range. Northern Queensland.
Habitat. Dredged at 668 m in firm clay and mud.

Comparisons and remarks. Cadulus rudmani n.sp., like the previous species, shows no close similarity to any other Australian species of the genus. Compared with the European-Atlantic C. ovulus (Philippi, 1844) and C. ampullaceus Watson, 1879 and the Indo-Pacific C. cyathoides Jaeckel, 1932, C rudmani is more inflated, the inflation situated centrally. Cadulus rudmani can also be compared with C. gibbus from the north Atlantic which has longer and more tapering aperture and apex. Cadulus rudmani resembles C. woodhousae in being a short, stocky species, but is more inflated and has pronounced contraction of the apex and aperture.