Grapsus longitarsis is a species of crab in the family Grapsidae, native to the Indo-Pacific. It was first described by James Dwight Dana in 1851, from a specimen found in the Tuamotu Archipelago, French Polynesia.
The basis for the decision of synonymy is Banerjee (1960).
G. longitarsis is a tropical, benthic species living at depths ranging from 0âÂÂ5 m in the intertidal zone. Precopulatory courtship (via smell and touch) is common and the sperm transfer is usually indirect.