This guide is designed for identification “in the field” where you might be looking at live crabs by eye or through binoculars or from photographs. I will generally try to avoid characters that will require you to physically catch the crab, although I may mention a few for secondary verification. It does not include the more strict taxonomist-style characters that may only be visible under a microscope or via dissection. It is also assumed that the individuals are living, as death (and even capture) can cause dramatic color change.
This is a guide to the fiddler crabs of the remote Ogasawara Islands of Japan. There is only one fiddler crab species currently known from these islands, so identification is easy.
Paraleptuca boninensis is the only fiddler crab found in these remote islands. It is very similar to Paraleptuca crassipes, but the two species do not overlap in space.
