Distinctive features are 1) ovate-fusiform, moderately high-spired shell up to 28 mm in height, 2) protoconch paucispiral, of 1.5 convex, smooth whorls, 3) teleoconch whorls convex, with the periphery placed abapically, meeting at impressed or slightly canaliculate sutures, 4) body whorl inflated, rather quickly tapering at the base toward a distorted neck, 5) aperture oval; outer lip swollen behind, with 9 inner ribs; distinct parietal denticle; abapical canal recurved with moderately deep terminal notch, 6) sculpture of collabral ribs overridden by spiral cords and intervening threads; the ribs, 14-15 on the penultimate whorl, tend to be obsolescent over the last half of the body whorl. Nassaria pusilla is rather variable in shell shape and sculpture. Nassaria coromandelica Smith, 1894, is closely related, but differs primarily in having a protoconch with 2.2 to 2.7 whorls and a less constricted base.
DISTRIBUTION AND HABITAT. The species is distributed from the Persian Gulf to Indonesia and northward to China Sea. It occurs in the 1-165 m depth range, dwelling in mud and coarse sand (CERNOHORSKY, 1981a; ABBOTT & DANCE, 1982). Nassaria pusilla was obtained from sandy mud, between 20 and 50 m depth along the west coast of Thailand (TANTANASIRIWONGANA, 1978: sub Siphonalia sp.).
FOSSIL RECORDS. Miocene of India; Pliocene of Indonesia.