Tubuca signata, the signalling fiddler crab,[1] is a species of fiddler crab that is found in Australia from Queensland to northwestern Australia.

[2] Tubuca signata males have one claw that is significantly larger than the other, while females have two equal-sized smaller claws.

The male adult upper claw (pollex) is smooth and bright white while the lower claw (dactyl) has a single groove along its length.

The wrist (manus) is red.

[3] The male carapace is typically up to 17 mm wide (95% of individuals are this size or smaller), with females slightly smaller.