It can be distinguished from related species by its exceptionally broad and knobbly main chela (claw).

The larger one is particularly broad and has teeth in the "molar area" and an immobile finger.

Individuals living in caves are paler in colour and have antennules with white spots.

[2] The knot-fingered mud crab is native to the subtropical western Atlantic Ocean, its range including southern Florida, Bermuda, the Caribbean Sea, the West Indies, and along the coast of South America as far south as Cabo Frio in Brazil.

[4] In fact, both male and female crabs are prevented from breeding and effectively castrated by the parasitic barnacle.