Berthelinia rottnesti is a species of a sea snail with a shell comprising two separate hinged pieces or valves.

It is a marine gastropod mollusc in the family Juliidae.

[1] The type locality for this species is Rottnest Island, Southwestern Australia.

[2] Berthelinia rottnesti is approximately 6 mm.

[3] This species can be found in algae and seaweed beds.