Cystiscidae – Cystiscinae: Cystiscus thouinensis (May, 1915) (‘Cape Thouin margin-shell’)

Synonym(s): thouinensis May, 1916 multidentata May, 1920.

Typical shell-length 2 mm. Lives in offshore waters under rocks and stones. Native. Endemic to southeastern and southwestern Australia (NSW, TAS, VIC, SA and WA).