Assiminea brevicula is distinguished by 1) globose-ovate, moderately low-spired, cyrtoconoid shell attaining 9 mm in height, 2) spire whorls convex, meeting at incised, adpressed sutures, 3) body whorl globose, with broadly rounded periphery, sharply attenuated at the base, 4) narrow umbilical chink, 5) aperture acutely angled adapically, outer lip thin, arched; inner lip following a reverse-S course, 6) outer surface with flat subsutural band bounded by a distinct groove occasionally followed by 1-2 faint spiral lines; a spiral microstriation is noted throughout; fresh shells are brick-red in color.

The species ranges from India to Western Indonesia and northward to China Sea. It occurs commonly in mangrove and Nipa swamps (BRANDT, 1974). Assiminea brevicula was recorded from mud, muddy sand and wood in mangrove forest along western coast of Thailand and southern Gulf of Thailand (TANTANASIRIWONG, 1978; SWENNEN et al., 2001).