Shell medium in size, 42.0 mm in height, 50.5 mm in length and 43.4 mm in breadth, solid, nearly squarish, slightly inequivalve; anterior side rounded and posterior wide and obliquely truncated, an obtuse angle from umbo to posterior ventral corner; surface sculptured with about 24 stout radial ribs, ribs of left valve granulated, covered with a brown epidermis.
Distribution: Hainan and Guangxi Provinces of China; Japan.
Ecology: Found in subtidal zone, uncommon in China.