This very small woodlouse, reaching 2 mm, is capable of rolling into a sphere when disturbed.  The head and body are covered in characteristic broad rounded tubercles (confusion only likely with Buddelundiella cataractae). However, the telson of R.costulatus has a characteristic ‘hour-glass’shape (also seen in Venezillo parvus) and it has truncated 'square' uropods typical of the familiy.

A description of this species, with figures, is given in Gregory (2014).